Intermittent fasting: The good things it did to my body | Hacker News Reader

Intermittent fasting: The good things it did to my body

bbc.co.uk

158 pointsgps408148 comments

I don't think we're even close to really understanding how the body works here.

I'm not obese, but I gain weight from eating a little more, very easily. Last summer, I followed a Keto ("ultra low carb, high fat, medium protein") diet for about 4 months. After the first week of feeling terrible, a well-known side effect, I felt perfectly fine. It felt like I was binge eating, I limited what I could eat and just went mad eating it. Any time I was remotely hungry, grab an approved snack. A big plate of bacon and eggs for breakfast, Chipotle for lunch, and a hefty meal for dinner.

I never went hungry, and as someone who likes food, it felt more like a treat than a diet. Colleagues thought I was trying to gain weight, and my girlfriend thought I'd gone mad with hunger. But the fat melted off. I didn't walk into a gym in those 3 months, and dropped 2-3lbs a week (starting ~250 at 6"3'), every single week.

I'm not saying it's perfect, or even viable for everybody -- it's not cheap, it's awkward to eat with friends, and the first week or two can be hell. Despite what people have been told, fat won't make you fat, and Keto has been shown over and over to reduce the risk factors for heart disease, 'cure' diabetics, and provide huge body transformations.

For anyone interested, /r/keto is a reasonably mature community, and can provide a lot more information.

I'm a physician. While it's good to lose weight (at least if you are overweight), keep in mind that losing weight is not the only interesting outcome. Any diet might have long term side effects. Such as an increased risk of cancer, arteriosclerosis etc.

Also remember that weight loss is not the only benefit of exercise.

That said, congrats on losing weight. Now start exercising :-)

"Also remember that weight loss is not the only benefit of exercise."

Weight loss is not part of any benefit of exercise. Though your statement is commonly held as a belief there is absolutely no scientific basis for your statement.

Anyone can easily verify this for themselves: take a chart showing calories in common foods beside a chart showing common activities and how many calories they burn and try to find any scenario where you can out exercise your mouth.

You've acknowledged that you do burn calories during exercise so consequently losing weight IS a benefit of exercise.

It is true that in general one should not depend on exercise only for losing weight. Watching what you eat is the easiest way of managing weight but it is a message often lost on many.

You are completely right it's surprisingly difficult to out exercise your mouth! When you do these calculations just remember to include the basic metabolic rate.

You are also right diet is the most important factor. You've got to eat less than you use.

However exercise causes you to expend more energy and even a small energy deficit will lead to weight loss over time.

Another important factor is that exercise helps to regulate appetite.

I personally think the increased appetite from exercise more than cancels out the benefits to weight loss. I've also read that before but I don't know if there is a really good study to back it up. Don't get me wrong, I think there are a zillion good reasons to exercise but losing weight will never be one of them.

By exercising one gains muscle mass, that consumes energy 24/7.

I've seen some very legitimate sources that show that this effect, while technically true, is irrelevant for fat loss in the real world due to increased appetite to build and maintain those muscles and the amount of passive calorie burning with more muscles is negligable.

Regarding the diet above, which limits your sugar intake to 20 grams a day, what are some potential consequences of starving your body of sugars?

Sounds good in theory (sugar is bad), but it sounds stressful (body starts producing ketones due to suck a lack of sugar, flu like symptoms for a week).

Producing ketones is perfectly normal. The flu-like symptoms can usually be avoided by easing into a low-carb/keto diet and/or ingesting sodium, chicken broth is normally recommended at the early stages.

Potential consequences of reduced carb intake are weight loss. It can be used to treat type 2 diabetes, epilepsy, a wide range of neurological disorders, some cancers (yeah, really), and much more.

I'm not aware of any scientic data that found adverse consequences. You get a lot of resistace from health professionals because for the last decades what you eat on a ketogenic diet has been blamed for heart diseases or high cholesterol, but there never was scientific evidence to back up those claims.

Here's a study that shows that while low-carb diets achieved effects faster (involved more weight loss in the first 6 months), after a year the difference in weight was negligible. Low carb diets led to higher levels of LDL cholesterol, which is generally considered to be bad, though were also correlated with better levels of HDL cholesterol, which are considered to be good. http://www.ceb-institute.org/fileadmin/upload/refman/arch_in...

Here is a a long term study that shows that low carbohydrate, high protein diets were correlated with higher mortality rates. It's an observational, not a controlled study, so the usual caveats apply, but it's definitely some evidence that there's no automatic win for low-carb, high protein diets: http://folk.ntnu.no/lyngbakk/artikler/trichopoulou.pdf

I'm pretty sure I've seen another study that linked long-term use of low-carb, high protein diets with increased incidence of cancer, but I can't find that study at the moment.

Thanks for those links. Yes, I should have been more specific, the diet I was talking about is low carb high fat (LCHF), not low carb high protein. Increased protein intake can indeed be a problem and seems to be common with low carb eaters.

Edit: Let me also add that meat consumption seems to be mostly problematic with processed meat (http://www.ncbi.nlm.nih.gov/pubmed/23497300)

Please don't promote "observational" studies. They are not worth the electrons it cost to display them on my screen let alone transmit them across the 'net.

You can find an 'observational' study to promote nearly any point of view. If it's not a properly controlled peer reviewed study it's not worth anyone's time except the shills who got paid to write it up by whatever corporate group commissioned it.

Wow, you definitely sound a bit too defensive. A bit like my sister, in fact. She also followed the ketogenic diet for four months and was very, very adamant about how it was healthy because she was finally losing weight. But then reality hit her hard. She had her blood samples taken before she started the diet and after the four month period. What the lab results showed clearly was dangerously elevated levels of LDL (from all the fried pig skins and bacon jerky she was munching on, no doubt). She finally realized that, despite what you read on the Internet, nothing beats the hard results you see on a lab report. She returned to a normal diet afterward.

Controlled studies about lifelong effects of fairly fundamental parts of your life such as diet are quite difficult to do, especially with large enough populations to be statistically significant and without being overly affected by their dropout rate.

Observational studies have significant problems, as I explicitly pointed out in my comment about the study. However, they have some advantages in that they are a lot easier to do for larger populations over a longer time period.

Both of these are valid scientific techniques, to inform us about what is most likely to be a healthy way to eat. There are, of course, other valid techniques, such as studying immediate metabolic effects of ingesting certain foods, and linking those to known risk factors for a variety of conditions. Science is not a single, infallible technique, it is a set of techniques which taken together are intended to give us the best approximation of the truth, though every method can fail in certain ways.

Diet is an especially difficult topic. Human bodies, human behavior, and differences between different people are quite complex. There are a lot of people who are afraid of diseases of affluence or degenerative diseases that you see coming up more often simply due to our longer lifespan. Lots of people are interested in solving these problems, and I think that a lot of people jump to over-simplifying conclusions on these topics. We've seen this played out in the past; a huge over-emphasis on low-fat diets, that seems to have left us unhealthier than ever. Warnings about dietary cholesterol, when it turns out that the cholesterol in our blood stream has very little correlation to cholesterol consumed.

Every time I hear about some new extreme diet that is supposed to work wonders, I get concerned. Low fat, low sodium, low carb, no carb, paleo, high protein, high fat, vegan, raw, gluten free, dairy free and so on. Most of these things seem to focus on some single source of evil, and claim to offer amazing benefits if you follow them. Most of those benefits don't actually play out; despite the huge push for low-fat diets over the 80s and 90s, obesity continued rising at an alarming rate. Despite the huge popularity of Atkins, "paleo", and other low carb diets over the past decade, it has continued to rise.

People keep searching for a silver bullet, and in diets, like much of life, there is no silver bullet. Eat less, exercise more, eat healthier foods like fruits, vegetables, nuts, and whole grains while reducing the amount of sugars and fats, avoiding too much processed food and so on is not some amazing new diet plan that you'll be able to sell some fancy book about, but it's pretty much the actual advice you need to follow if you want to stay healthier.

Anyhow, I see this over and over again, and then I hear from eager people who want to tell me that low-carb, no fasting, no gluten free, no lactose free diets will help them lose weight, prevent cancer, prevent heart disease, prevent Alzheimers, prevent autism or ADHD, do all of the above and more, and there's no risk, they're so healthy, why would anyone not do this? And then I read the literature, and I find that actually, this new diet has quicker effects in the first six months but is about as effective as the last fad diet was after a year, and actually it does have certain dangers, and so on.

Eat less, exercise more, keep it healthy. Beyond that, don't worry too much, and do everything in moderation. Take all dietary science with a grain of salt, since it's a tough field to study the real, long term effects of (20 year studies are considered to be long term studies, but that's only a fraction of a life, meaning that many real long term effects get very little study). Take industrial food with an even larger grain of salt, as it's more likely optimized for shelf life, profitability, or narrow nutrition claims to be able to put some particular label on it, rather than flavor and health. Don't drink soda; I don't care if it's regular or diet, or whether the sugar is corn syrup or cane sugar. Soda is always extra calories that you don't need, or extra sweetness sans calories that confuses your body. And don't drink venti mochafrappucaremelates, or whatever the hell they're called. Don't eat salty snacks on a regular basis, but don't be afraid to put a pinch of salt in your food to make it taste good. Don't have dessert with every meal, but don't be afraid to have a slice of cake at a birthday party.

Anyhow, rant over. I just get upset when I see people getting religious over some new diet fad, which in 10 years will be the diet that the people selling a new diet fad will be talking about in their "you've been lied to for all of these years. Learn how to really stay healthy and lean!"

I didn't really see anybody getting religious, but why is it you get so emotional about this?

> Eat less, exercise more

So eating above one's caloric requirement and a lack of energy are always problems of willpower?

> eat healthier foods

I think everybody can get behind this, it's like thinking of the children.

> fruits, vegetables, nuts, and whole grains while reducing the amount of sugars and fats, avoiding too much processed food

So grains healthy, fat bad? As you don't mention meat that's probably also bad? Well, it's the details that get interesting, what are healthy foods.

> I didn't really see anybody getting religious, but why is it you get so emotional about this?

It's just that there have been one too many threads of people promoting some particular fad diet idea (gluten is poison! sugar is poison! soylent is the food of the future!) and I'm getting kind of sick of them. I've been hearing these fad diet ideas for years, it's just different things which are claimed to be the poison or different combinations of things or combination of restrictions which are claimed to be the be-all cure.

This thread hasn't been particularly bad, though you were a bit overly pushy about ketogenic diets and dismissive of criticisms of them earlier: "I'm not aware of any scientic data that found adverse consequences. You get a lot of resistace from health professionals because for the last decades what you eat on a ketogenic diet has been blamed for heart diseases or high cholesterol, but there never was scientific evidence to back up those claims."

> So eating above one's caloric requirement and a lack of energy are always problems of willpower?

No, there is not always a problem of lack of willpower. Metabolism plays a role, though diet and behavior play a big role too. There are certain circumstances for which ketogenic diets are appropriate, just like there are certain circumstances for which gluten free diets are appropriate; likewise, just because they are appropriate and effective in certain cases doesn't mean they are appropriate or effective for every case.

I think that for a lot of people, however, the problem is willpower. There are a lot of people who just want an easy excuse or an easy answer, when there really is an easy answer that just takes a bit more willpower.

I do believe that the low-carb, paleo, ketogenic, and likewise diet fads have at least helped combat the harmful emphasis on low-fat above all else. I recall at the height of the low-fat craze finding lots of fat free and low-fat foods that were stuffed with tons of sugar to compensate.

> I think everybody can get behind this, it's like thinking of the children.

No, I don't think everyone can get behind it. There are a lot of people who take the "you can eat whatever you want as long as it's not carbs" idea and eat way too much bacon, pork rinds, and the like.

Fresh fruits and vegetables are healthy. Eating pork rinds instead of a banana because the banana is fairly carb rich and the pork rinds are not is not healthy.

> So grains healthy, fat bad? As you don't mention meat that's probably also bad? Well, it's the details that get interesting, what are healthy foods.

I don't think dividing it into "this entire category of food is healthy, this food is not" is a good way to approach your diet. So no, I'm not claiming "grains healthy, fat bad". Both grains and fats are good for you, in moderation. Likewise meat. All of these things can be bad for you when taken to excess; eating too much meat can give you cancer (and some meats are fattier, leading to the problems with too much fat), too much fat can raise your cholesterol leading to heart disease, too much grains (especially highly refined grains) can lead to spikes in blood glucose and harm your insulin response.

What I'm saying is favor fruits and vegetables over grains, favor whole grains over refined, treat meat as a supplement, flavoring, or occasional treat rather than the central part of every meal, favor unsaturated fats (generally vegetable oils and fish) over saturated fats (generally from other animal sources), and keep refined sugar consumption very low. If you need to lose weight, eat a little less, and try to fill up a little more on things without much caloric value like greens (but don't go spending all of your time eating salads, as they generally come with dressings that consist mostly of fat and sugar, defeating the whole point).

Personally, I follow this by eating meat (of any form, fish, poultry or red meat) only about 3 times a week. I never drink soda (can't stand the stuff now that I'm not used to it any more). I generally use unsalted nuts or fruit as a snack if I need something to tide me over between meals (but don't snack often). I usually buy whole grain bread. But I cook with butter plenty (as well as with olive oil, I love sauteing food in a combination of the two), I put cream in my coffee, I enjoy the occasional juicy steak, I eat a lot of cheese (my one main vice), and I have the occasional dessert.

Now, I don't claim that my diet would work for everyone. That's why I'm not out selling it; it's just what happens to work for me. But I do think that it's good to employ an approach of moderation and avoiding thinking about food in black and white terms, unless there's a very good reason why a food should be completely banned (like if you have celiac disease, a nut allergy, or a moral objection to consuming animals).

> too much fat can raise your cholesterol leading to heart disease

Actually, foods with a high glycmic load seem to be what's really bad for the heart http://www.ncbi.nlm.nih.gov/pubmed/19364995

> favor unsaturated fats (generally vegetable oils and fish) over saturated fats (generally from other animal sources)

Doubtful, http://ajcn.nutrition.org/content/early/2010/01/13/ajcn.2009...

Polyunsaturated and monounsaturated oils have to be balanced. Too much omega-6 rich polyunsaturated vegetable oil like from soybean or corn may actually increase risk of heart diseases, http://www.ncbi.nlm.nih.gov/pubmed/16387724, http://www.ncbi.nlm.nih.gov/pubmed/21118617

> though you were a bit overly pushy about ketogenic diets and dismissive of criticisms of them earlier

Seriously, you keep calling LCHF keto a "fad diet" and accuse people who talk about it of "selling books", calling it the "be-all cure" or eating "way too much bacon, pork rinds, and the like". Your underlying tone is really ad hominem, you seem to think all ketoers are stupid, uneducated or in it for a quick buck.

Edit: Let me also add that keto is a proven treatment for diabetes, epilepsy and there is currently research into more therapeutic benefits: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1325029/, http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2367001/, http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3826507/

> Actually, foods with a high glycmic load seem to be what's really bad for the heart http://www.ncbi.nlm.nih.gov/pubmed/19364995

From the referenced study: "associations of harmful factors, including intake of trans–fatty acids and foods with a high glycemic index or load"

You seem to have missed the other half of that statement.

> Doubtful, http://ajcn.nutrition.org/content/early/2010/01/13/ajcn.2009...

From the study you link to:

"Of note, in intervention trials that have shown protective effects of reducing saturated fat, ie, the Veteran Affairs (19), Oslo Diet Heart (20), and Finnish Mental Hospital (21) studies, the calculated P:S ratios ranged from 1.4 to 2.4—values that are much higher than the threshold of 0.49 above which CHD risk has been reported to be reduced (44). Relatively high P:S ratios (1.25–1.5) were also observed in the Anti-Coronary Club Study, an early trial that showed beneficial effects of a lower fat diet (30–32% of total energy) (45). The presumed beneficial effects of diets with reduced saturated fat on CVD risk may therefore be dependent on a significant increase in polyunsaturated fat in the diet. Existing epidemiologic studies and clinical trials support that substituting polyunsaturated fat for saturated fat is more beneficial for CHD risk than exchanging carbohydrates for saturated fat in the diet, as described further elsewhere (46)."

Exactly as I said, favoring unsaturated fat in diets over saturated fats seems to have benefits as far as cardiovascular disease, while replacing fats with carbohydrates leads to poor results.

> Polyunsaturated and monounsaturated oils have to be balanced. Too much omega-6 rich polyunsaturated vegetable oil like from soybean or corn may actually increase risk of heart diseases

Sure. I wasn't trying to lay out every possible dietary guideline, just a few rough ones. And I really mean them as rough, and meant to be broken. I don't believe that we know enough about dietary science at the time to make strong judgements; making drastic dietary changes on the basis of poorly understood science can be a bad idea.

One rough metric for whether a diet is good to eat is whether it a similar diet has been eaten over the past few hundred years by agricultural societies; that gives at least some evidence that it works over a large population for a long period of time. It's not perfect, and modern scientific understanding can help us understand and improve it, but it gives you a good baseline.

I don't really buy the paleo idea that we evolved for the hunter gatherer diet, and then evolution stopped; after all, Europeans evolved white skin as a result of agriculture, so I find it a lot more plausible that our digestive system has likewise adapted to agriculture, though it's too quick for it to have adapted to modern industrial agriculture and food processing.

Given that we've been eating butter, olive oil, and lard for centuries, while corn and soybean oil are inventions of modern agriculture, I tend to favor the former over the latter.

> Seriously, you keep calling LCHF keto a "fad diet" and accuse people who talk about it of "selling books", calling it the "be-all cure" or eating "way too much bacon, pork rinds, and the like". Your underlying tone is really ad hominem, you seem to think all ketoers are stupid, uneducated or in it for a quick buck.

I do think that there's a LCHF/keto fad. I've seen a lot of fad diets over the years, and it has all the trappings of one. I don't think that all ketoers are stupid, uneducated or in it for a quick buck, but I do think that lots of well meaning, smart people can get caught up in fad diets, just like the low-fat fad that was popular for so long (and still has plenty of vestiges in nutrition advice and policy today).

That doesn't mean that that there aren't valid uses for a keto diet. That has been demonstrated in a variety of studies, and a classic example is in epilepsy. What I don't think has been demonstrated is the long-term efficacy of keto diets over normal calorie restricted diets. Keto tends to get results quicker (at the expense of some unpleasant side effects) but the advantage tapers off after a year.

On the other hand, low-fat diets are useful for specific therapeutic purposes as well, such as people having gallbladder problems. We've all seen the damage that over-emphasis on low-fat diets for the general population has done. Look at all the trans-fats people have consumed while avoiding saturated fats; and all the sugars that have been substituted for fats in foods to try to make bland processed food taste better.

From the evidence I've seen, I think that low-carb is likely to be a bit safer than low-fat as it's easier to wind up consuming more calories in carbs when eliminating fat than vice versa, but I do worry that too many people deciding to jump on the low-carb high-fat or low-carb high-protein bandwagon may wind up doing themselves harm; possibly from causes that we already know, and possibly from things that we don't know.

By the way, I think you've mistaken what ad-hominem is. An ad-hominem attack is one in which you attack a person rather than their ideas. That's not really what I've done; I've just been fairly dismissive about the idea. Perhaps I've been unduly dismissive, but having recently been in a thread discussing gluten free diets, I'm feeling a bit uncharitable towards the tendency for people to latch onto a dietary idea that is a very effective treatment for a very specific problem, and decide that it's the solution for everybody and must be evangelized far and wide.

> From the referenced study: "associations of harmful factors, including intake of trans–fatty acids and foods with a high glycemic index or load" > You seem to have missed the other half of that statement.

What the actual frack? No, I can read, and we weren't talking about trans-fatty acids at all, how on earth could I have missed something we're not talking about? Or did I promote eating processed foods?

Anyway, this doesn't seem to lead anywhere, you have made up your mind.

I did a diet like this years ago.

One of the possibly side effects is decreased kidney function from the rapid increase of proteins in the diet (which don't metabolize very cleanly compared to fasts or carbohydrates). People with kidney issues or possible problems should avoid these diets. Kidney stones are much more common IIR.

Another is lower bowel problems as these diets frequently don't have enough fiber in them to keep things moving.

I lost a ton of weight (about 60 pounds) but I also had some weird problems that made me give it up:

- I felt unbelievably hungry all the time. Even after eating a huge meal. This is supposed to go away after a few weeks, but months into the diet I still felt like this.

- I felt like grease was oozing out of me at all times. I just felt icky and couldn't ever feel completely clean.

- My hair and fingernails grew at astonishing rates. I was cutting my nails every 3 or 4 days at one point.

- I had wretched B.O.

- I was constipated all the time. Low-carb fiber supplements solved this.

Good things:

- My mental clarity was unbelievable. You don't get drowsy in the middle of the day, and you don't really need anything to help wake up.

- I was doing lots of sports then and injuries healed so fast I felt like Wolverine. I never bruised during this time and I was doing full contact kickboxing.

- I was easily the strongest I've ever been.

- Weight loss was pretty constant till I hit a nice comfortable plateau at a good weight for me (a little under 160).

I've also done vegetarian diets and for a brief spell vegan diets. It's hard to compare how much better I felt overall on the first diet than the vegetable based ones though.

"One of the possibly side effects is decreased kidney function from the rapid increase of proteins in the diet (which don't metabolize very cleanly compared to fasts or carbohydrates). People with kidney issues or possible problems should avoid these diets." You are confused and incorrect on this point at least, I recommend anyone considering this to go to some legitimate sources of information. There is a liver condition that is unrelated to ketogenic diets which people confuse mightily.

Nope, I'm definitely correct on this point. There's an unbelievable amount of bullshit in ketogenic diet circles about it - to the point an absurd reverse of well researched results. It's one of the very well researched downsides of any low-carb, high protein diets. The trick is to eat low-carb and low-protein as high-protein diets simply aren't good on kidneys. But then you're basically just eating fats and that gets boring. It's very hard to get dietary fats without one or the other though.

https://en.wikipedia.org/wiki/Ketogenic_diet

http://site.matthewsfriends.org/uploads/File/StonesPolycitra...

http://www.webmd.com/diet/high-protein-low-carbohydrate-diet...

"By restricting carbohydrates drastically to a mere fraction of that found in the typical American diet, the body goes into a different metabolic state called ketosis, whereby it burns its own fat for fuel. Normally the body burns carbohydrates for fuel -- this is the main source of fuel for your brain, heart ,and many other organs. A person in ketosis is getting energy from ketones, little carbon fragments that are the fuel created by the breakdown of fat stores. When the body is in ketosis, you tend to feel less hungry, and thus you're likely to eat less than you might otherwise. However, ketosis can also cause health problems, such as kidney failure (see below)."

"What Are the Risks Linked to High Protein, Low-Carb Diets?

High protein, low-carb diets can cause a number of health problems, including:

Kidney failure. Consuming too much protein puts a strain on the kidneys, which can make a person susceptible to kidney disease. High cholesterol . It is well known that high-protein diets (consisting of red meat, whole dairy products, and other high fat foods) are linked to high cholesterol. Studies have linked high cholesterol levels to an increased risk of developing heart disease, stroke, and cancer. Osteoporosis and kidney stones. High-protein diets have also been shown to cause people to excrete a large amount of calcium in their urine. Over a prolonged period of time, this can increase a person's risk of osteoporosis and kidney stones. A diet that increases protein at the expense of a very restrictive intake of plant carbohydrates may be bad for bones, but not necessarily a high-protein intake alone. Cancer. One of the reasons high-protein diets increase the risks of certain health problems is because of the avoidance of carbohydrate-containing foods and the vitamins, minerals, fiber, and antioxidants they contain. It is therefore important to obtain your protein from a diet rich in whole grains, fruits, and vegetables. Not only are your needs for protein being met, but you are also helping to reduce your risk of developing cancer. Unhealthy metabolic state (ketosis). Low-carb diets can cause your body to go into a dangerous metabolic state called ketosis since your body burns fat instead of glucose for energy. During ketosis, the body forms substances known as ketones, which can cause organs to fail and result in gout, kidney stones, or kidney failure. Ketones can also dull a person's appetite, cause nausea and bad breath. Ketosis can be prevented by eating at least 100 grams of carbohydrates a day."

There's tons more. But I can't be bothered right now.

That's with respect to high protein diets, and not necessary to keto, which is typically a medium protein, high fat diet. I'm also not certain an uncited webmd link is the best nutritional reference.

Seriously, if webMD is getting canned as a fringe site these days with inaccurate medical information and nothing to counter their medically accurate information, then there's literally nothing you can trust on the internet.

It's literally the accredited health care information site.

I'm not saying that their information is free from being wrong, just that given a standup between webMD and some random keto blog, I'll go with webMD.

Regardless of the source of dietary calories, a diet that triggers ketone production, which is the point of a ketogenic diet, introduces ketones into the bloodstream, which are processed in the kidneys.

Because there appears to be at least 2 people on HN who don't know about ketones (a family of organic compounds that includes acetone), but know about ketogenic diets, a well known and researched diet intended as a medical aid for epilepsy in children with a wealth of academic research on the effects of the diet both positive and negative. But it's also used widely to treat type 1 diabetes. Since diabetics often have reduced kidney function, ketone management can become critically important.

We know that ketogenic diets stress kidneys. This is basic information known to medicine. It's about as basic anatomy.

Other well known side effects include bone demineralization, constipation (which increases risk for colorectal cancer and other lower digestive complications), menstrual irregularities in women, increased colestrerol (up to 30%!), kidney stones are recorded at rates as high as 1 in 20, acidosis and all that includes.

It's considered as a diet that you should only go on under doctor supervision and constant blood tests.

Anecdotally

I've gone on keto 3 times, for different periods of time, and after being off of them for a month or so, I've developed kidney stones.

I have no idea if they're related, but I am the only one in my family that gets them (no medical history) and it's the only 'abnormality' in my normal, generally healthy, life.

Kidney stones are a well known side effect of ketogenic diets.

The liver produces all the glucose that your body needs, which is mostly used by the brain. The likely consequence is that you might need to eat more protein to replace the amino acids scavenged for this purpose.

In practice, you cannot contract a dietary deficiency disease from eliminating sugar unless you have a genetic defect affecting liver function. Even if you also eat no protein, your body will self-cannibalize muscle tissue to keep the brain alive.

It appears as though the evolutionary pressures on humans have produced support for two different energy metabolisms. In times of feast, where sugars and starches are consumed in excess, the body operates on glucose and glycogen, and stores fat. In times of famine, the body operates on ketones produced from its own body fat, and the brain operates on a combination of lactic acid and sugars scavenged from the body's protein stores.

The potential consequence of this is that if you ever do start eating significant quantities of sugar, your body will chemically signal that famine is over, and prioritize the restoration of your body fat stores. In other words, you can never go off the diet if you want to maintain your weight, as your body will want to turn every last scrap of excess sugar into fat as fast as possible.

This seriously sucks, because the brain is hardwired to love sweeter foods--foods that surround us constantly. It's like Lou Wu from Niven's Ringworld resisting the urge to eat the magic sweet potato that turns Pak breeders into protectors. Your limbic center wants that doughnut, no matter what that prudish frontal lobe says. So low-carb dieters have to consistently maintain a high level of sheer willpower for their entire lives. That may not be physically stressful in the cortisol-producing sense, but it is stressful mentally.

Sugar is a rather broad term, I'm assuming you mean white refined sugar (sucrose, a disaccharide).

You absolutely don't need to to eat any sugar at all. Simply put, glucose (a monosaccharide) is what normally power our cells. Glucose can be produced from hydrolyzing longer carbohydrates, or even from fat and proteins via gluconeogenesis.

Suggested reading:

http://en.wikipedia.org/wiki/Gluconeogenesis

http://en.wikipedia.org/wiki/Citric_acid_cycle

http://en.wikipedia.org/wiki/Sugar

> what are some potential consequences of starving your body of sugars

If you look at history we've never had so much sugar in our diet at any point in human history, not to mention the fact that most sugar isn't actually sugar but things like HFCS which has a higher glycemic index.

The keto flu may sound bad, but it happens because your body isn't used to producing ketones since you've never been in ketosis before. I've been on and off keto for the last two years, and I don't get a keto flu since the first time I went into ketosis.

> flu like symptoms for a week

People assume that's a bad thing, but that's not a trivial assumption. Yes, it's not convenient - but e.g. fever - while indicative of a disease, is most of the time a good thing (unless it is life threatening, taking down the fever with Tylenol or Advil is likely to prolong the disease). Those flu- like symptoms might be a good, if uncomfortable, process.

I don't know myself - I'm just pointing out that it is not necessarily an indication that keto is bad for you.

I'd be curious to read be your response to this - genuinely asking here (skip to 37:30)

http://www.youtube.com/watch?v=y1RXvBveht0

Thanks for bringing my attention to this interesting video.

I can't really comment on the facts since I neither read all the studies or had time to watch the whole video.

I'm not an expert in nutrition so this is my personal opinion. I think he's raising some valid points:

* It's a surprisingly difficult subject to study.

* There're a lot of bad studies.

* There're a lot of dubious conclusions.

However, losing weight is just a matter of energy balance. If you consume less energy then you "use", you will lose weight. Consuming less can be done in many different ways. As can "using" more. Different diets may however bring additional advantages (such as decreased risk of cancer).

It also depends on what you are doing with your body, for example, you won't find many tour de France cyclist eating low carb before a race.

Thanks for replying.

So why are you still of the opinion that losing weight is just a matter of energy balance? Are you familiar with other studies which have shown this claim to be correct?

As you can probably tell, I'm a low carber myself, but I'm genuinely curious to understand how did the "energy balance" consensus opinion form. It seems that currently, both opinions aren't rooted in scientific studies. BTW, there's an initiative called nusi.org that attempts to solve this once and for all (by proving low carb diets are right and everyone else is wrong, of course :-)

It's a simple matter of physics and biology that it comes down to energy balance.

The hard part is accurately measuring inputs and outputs and whether some diets will make it easier for a given individual to maintain their inputs below their outputs.

Let me phrase it like this. If you consume less calories than you expend, you are going to lose weight as the body will used stored chemical energy to survive.

I can recommend the BBC Horizon documentary "Why Are Thin People Not Fat"

Homework: Exactly where does they weight you lose go?

fulmato, you were hellbanned after your first comment saying "this is bs". Not a great comment, but hellbanning for a single comment is quite extreme. Posting your useful comment here:

On top of /r/keto Dr. Peter Attia has a great blog on this topic http://eatingacademy.com/ It's a great resource for a more scientific explanation of what happens to the metabolism when keto-adapted and on the effects of carbohydrates and more importantly insulin.

People like Attia live in a parallel universe where there are healthy populations on Earth that eat no carbs and East Asia doesn't exist. My Japanese is good enough now to explain to my wife's active octogenarian grandparents why rice is going to give them heart disease and diabetes.

In all seriousness, the world of online nutrition is a nasty and insane place. There's a lot of dogma and cognitive dissonance in something that borders on religion among the followers of gurus like Attia. If you're simply looking for an objective explanation of science rather than an ideology, look elsewhere.

To my knowledge Attia has never claimed a low-carb diet is right for everyone, rather quite the opposite.

> the world of online nutrition is a nasty and insane place

Attia would agree with you, and not just regarding online nutrition, but nutrition as a whole. He started NuSi [1] not to promote his low-carb lifestyle, but to promote independent nutritional research, since there's clearly something wrong with what we're doing now and the motivations of government- and industry-sponsored research are questionable at best.

[1] http://nusi.org/

There's a lot of scientific evidence supporting a ketogenic lifestyle, distinguishing this movement from fad diets and Attia from a Guru status. If you're interested I would recommend the following book: http://amzn.com/0983490708

Better would be peer-reviewed journal articles. A lot of books have a tendency to promote the views of the author over providing a balance of information.

Here is a short list of both author's peer-reviewed research papers on the topic. http://www.artandscienceoflowcarb.com/research/

Interesting. Their two-week adaptation time is consistent with what I noticed in myself. I don't do the diet this strictly. I simply commented to a trainer that I have never been able to successfully work out hard- meaning weight lifting an anaerobic interval training- and lose weight simultaneously.

He suggested I try working out while fasting. Just don't eat 3-4 hours before working out, and have a high quality protein 'meal' (I drink a shake) after the workout.

So far it's been working for me. And I've been working out since I was a young teenager- some three dozen years now.

I have no background in science, and was totally sucked in by one of Gary Taubes' books precisely because of that. A lot of these authors are incredibly biased and happy to filter science to you in a way that's profitable for them. Volek and his Superstarch is someone I have little respect for. If you haven't come across it, and you're willing to listen to a different viewpoint, I really recommend http://carbsanity.blogspot.com Have a search for Attia, Taubes, Volek etc and you may find some surprises.

See also Prof Timothy Noakes, a professor of exercise and sports science, also a marathoner and ultra-marathoner. He struggled with his weight and pre-diabetic status until himself switching to a ketogenic diet.

http://www.runnersworld.co.za/nutrition/novel-dietary-ideas/

He doesn't say a ketogenic diet is right for everyone, rather that some people are very sensitive to carbs ("carbohydrate-resistant") and would be best served avoiding them.

I too swear by keto. 65 lbs in ~4 months while never feeling hungry and having massive amounts of energy (hormonal changes crank up your testosterone levels)

Nothing else I've tried was as easy as keto... And as a guy with >65lbs to lose I've tried a lot of diets.

I don't know if it is for everyone, but my body responds really well to it.

Chipotle for lunch

How did you do Chipotle? I'm guessing you just went with beans / meat / vegetables and skipped the rice and tortilla?

They have a pretty decent nutritional guide[1] on their website, my usual was the salad bowl (big lettuce), no salad dressing, no rice, no beans, fajita veggies, double meat steak + barbacoa, the green salsa (has the fewest net carbs), sour cream, cheese, guac. That leaves you with this: http://imgur.com/WZBEczv, 14g net carbs (net carbs = carbs - fiber). My target was <30g per day. Breakfast gave almost 0, dinner would be 10-15g.

[1] http://www.chipotle.com/en-us/menu/nutrition_calculator/nutr...

Did you notice any long term (lasting) effects after those four months? Also, any particular reason you stopped?

Thanks.

Maybe I can answer this question, been on a ketogenic diet for over a year now. As mentioned above there is an adaptation period to the diet that can take up to 4 weeks. During that time symptoms can be flu like, this is caused by an initial hormonal change due to low blood glucose levels and in return a low and stable insulin level. Because of this the kidney excretes more sodium, potassium and water, leading to low blood pressure. This can be prevented by supplementing broth, or adding more salt to servings, for as long as the symptoms occur. Once this phase is over you get to experience the real benefits of a ketogenic diet, constant energy levels throughout the day, controllable hunger, better sleep, elevated HGH and more. It really sounds too good to be true I guess, which is why a lot of people dismiss it right away. I'd encourage anyone to give it a try, at least 4 weeks however to ensure adaptation.

This is pretty much the "reset fast" that is advocated by the "Engineering the Alpha" book.

HGH? Human Growth Hormone? Just curious, what benefit does this provide?

From the wikipedia page: "In addition to increasing height in children and adolescents, growth hormone has many other effects on the body: - Increases calcium retention, and strengthens and increases the mineralization of bone - Increases muscle mass through sarcomere hypertrophy - Promotes lipolysis - Increases protein synthesis - Stimulates the growth of all internal organs excluding the brain - Plays a role in homeostasis - Reduces liver uptake of glucose - Promotes gluconeogenesis in the liver - Contributes to the maintenance and function of pancreatic islets - Stimulates the immune system"

After I stopped, and started eating regularly again, I found nothing different at all. One of the side effects, is that you're really susceptible to alcohol. One beer, and I'd be really feeling it. Whereas before, I could drink 3 without really noticing. After I stopped, my tolerance was still pretty low, though it's fine now. I don't know if the low tolerance afterwards could be the diet specifically, or just whether I'd not really drank in 4 months.

I stopped because it was just too awkward. Living with my girlfriend, it was annoying that we had to cook separately (she only believes in low calorie, zombie cardio 5 days a week). We could only go out to dinner at certain places, which got a bit tedious. And to be honest, I'd done pretty well, and was back to the sort of weight I wanted to be at. The toss up between the cost/awkwardness, and the amount of weight I still had to lose, it wasn't worth the hassle.

Though, if I ever need to lose weight again (hopefully never), I wouldn't even dream of anything else.

> One of the side effects, is that you're really susceptible to alcohol. One beer, and I'd be really feeling it. Whereas before, I could drink 3 without really noticing. After I stopped, my tolerance was still pretty low, though it's fine now. I don't know if the low tolerance afterwards could be the diet specifically, or just whether I'd not really drank in 4 months.

After going Keto/IF my alcohol tolerance has gone through the roofs to a point that I really don't want to get wasted anymore (not that I did it that often). Around 10 beers used to get me in a great buzz, but now after a 0.7 litre bottle of whisky I could still easily get into a bar and continue drinking. But luckily there is something going in the back of your head, that "maybe this is way too much already, lets call it a day". And top of that, the day after, I seem to have no hangover at all. Now a days, if I go out with friends I usually take one or two servings of some good quality whisky and leave it at that.

For the background I'm currently standing at 115kg

The book "The Endurance: Shackleton's Legendary Antarctic Expedition" mentioned about the group not able to eat carbohydrate for months. They had only animal products available to survive. They complained about lack of stamina and each physical tasks taking a lot longer to complete.

They were stuck on an Antarctic ice floe for 497 days, and you think it was the lack of carbs that reduced their stamina? What about the debilitating cold, the crushing expectation of a lonely death, or the general ice-induced boredom?

What's a big plate of bacon?

5 or 6 slices of bacon and 3 eggs is in the ballpark of 500 calories, which is a fairly light meal for someone at 200 pounds.

Waxy fat though. Gotta watch those arteries. Damn tasty pork.

There’s a growing amount of evidence and debunking of past research showing that fat - predominantly the saturated fat found in stuff like bacon - doesn’t clog arteries.

And even if it did, you don't have dangerous atherosclerosis until those clogs start to calcify. The interactions between calcium, magnesium, vitamin D, vitamin A, vitamin K, collagen, silicon, and boron also somehow affect this process, but the exact mechanisms are not yet fully understood by scientifically sound research. I do not know of any human studies planned or underway on the hypercalcemia hypothesis for heart disease.

The pop-science gurus claim that obstructive heart disease is primarily caused by consuming calcium in excess without attending to the other related dietary factors, and this causes the excess dietary calcium to harden arterial plaques rather than bones and teeth. They are usually pushing magnesium supplements or organic butter oil or some other purchasable product.

Interesting to see how mainstream intermittent fasting has become. It's worth noting where it started.

A few years ago a few hardcore fitness fanatics started playing with the idea of using controlled fasting for weight loss and/or body recomposition. Two people that should be mentioned are Lyle McDonald[1] and Martin Berkhan[2]. Martin especially made IF popular via his blog, laying out the principles he used as a fitness consultant with his clients.

Most research (and especially the commercial IF knockoffs) only take some part of these principles, but the "diet" part is only part of the picture when it comes to body recomposition. It's almost worthless without the rest (high intensity, low volume weight training, basic compound movements, progressive overload, no focus on cardio).

Quite a few people/company are trying to rip off customers via their IF programs knockoffs and supplements. If you want give IF a shot, read through Martin's blog, and try the original Leangains protocol.

[1] http://www.bodyrecomposition.com/ [2] http://www.leangains.com/

Another recommendation for Leangains.com - been following it for over a year and have seen good results. Although I haven't followed the protocol to the letter - I eat a good amount of junk food during the week, but also good food as well. The point is to narrow your window of time that you eat during the day. I believe I could be doing even better if I concentrated on eating better and cutting out the crap, but now I have a pretty good balance of being in shape and being able to eat what I want.

Dr Mercola also has some really good articles on IF - www.mercola.com

I also have a couple of years of leangains under my belt. Doing the fasted early morning training (modified stronglifts) with a feeding windows 10am-6pm. It gives me energy, I don't ever really feel hungry and my muscle gains have been good. Only thing is you really have to watch your macros. You can still gain fat on IF. I made it down to 9% BF by watching caloric intake and when I decided to just try eating as much of whatever I wanted to get some bulk I gained weight and BF (now 16%). Recomp (losing fat and gaining muscle at the same time) is hard and slow

Best part is that it has been a cinch to stick to. I simply don't get hungry during that 16h window

The whole "clean eating" thing is mostly a fad. Nobody has managed to define what food is "clean" and what is not (see e.g. what the typical bodybuilder thinks is clean, and what someone doing paleo, what the average dietitian recommends, etc). The only important things are 1) the number of calories you eat, and 2) what nutrients your diet provides.

When I'm cutting, I don't make a fuss about "junk food", as long as I'm below my calorie intake limit and I'm not missing any important nutrient. Usually hovering around 20% junk food.

Do you mean: 1000 kcalories of fries and soda == 1000 kcalories of vegetables, fruits and grains?

If you're only looking into weight loss/gain, then yes. Both are terrible choices as a diet, though. The latter will provide more nutrients, so we can call it 'healthier', but you will lack important ones still, and significantly undereat if you are an adult male of average weight and height.

There was a very interesting documentary on intermittent fasting on BBC Horizon titled 'Eat, Fast, Live Longer' where Michael Mosley experimented with himself fasting trying different types of fasting including intermittent fasting.

It did help him alot but the cool thing was there was a guy who lived on a meal a day which had athlete like body fat levels.

There's also a runner, Fauja Singh, who ran a marathon at 101 years of age featured in it who practices something close to intermittent fasting [1]

It was extremely interesting and I do feel after watching it that 3 meals a day is something conjured by man but may not really be all that natural.

Link to episode intro: http://www.youtube.com/watch?v=gGHDBIaibok

[1] http://en.wikipedia.org/wiki/Fauja_Singh

Looks like a derivation on the 5/2 diet. The 25/5 diet. My personal issue with these types of diets is that my concentration levels initially drop. I find the first couple of days extremely uncomfortable.

The best lifestyle change I've made is to drastically cut down on carbs, generally avoiding wheat and try never to eat sugar, in particular fructose. Note this doesn't stop me eating carbs but that I generally try and avoid them in my day to day eating. I no longer feel tired in the afternoon.

I also cycle to work.

What did wheat do to you? Are you a celiac, or are there other reasons one might be interested in avoiding it?

Not op - My experience is that all grains (corn, rice, wheat) make me bloated and puffy, regardless of caloric content. Wheat is by far the worst offender, also making my breath shorter about 30-60 minutes after eating, lasting a couple of hours, and corn not having an immediately noticeable effect, but causing bloating that will stay for days.

Not celiac, and not anything life threatening, but definitely a huge effect. After dropping wheat, I lost 30 lbs in one month, and it stayed off for 18 month without wheat (but some came on again after a week of eating mostly corn products - which is how I discovered that corn is evil too)

The best way to determine if this is relevant to you is not to read books or articles or consult with a doctor: rather, take a week or two off grains (much harder than it sounds - wheat and corn are used as fillers in many products), and then adding them sporadically and keeping a journal (what and when you ate each day; and whether you felt good/bad the next hour/day)

Not easy, but well worth it and not expensive.

Please please do this. It's what I did. If you find similar affects, this can be life changing in a very very beneficial way.

As some others have noted, white flour products and other high-carb, high glycemic-index foods tend to lead to hunger in the short term and lethargy ('food coma').

Anecdotally, I've noticed that if I eat a small breakfast high in protein - e.g. 3 eggs - then I don't get hungry for several hours. If I eat a large breakfast high in carbs - e.g. pancakes or waffles - then I am hungry much sooner.

I think it was a combination of issues:

1) If I eat a carb rich meal, I will happily go for a nap. Anecdotal evidence, had spaghetti carbonara with garlic bread at the weekend. Fell asleep watching a film for the first time in about a year. I can create the same effect with potato or rice. I don't like it. It wastes my time.

2) After eating a lot of bread I can feel extremely bloated and uncomfortable. I potentially have a gluten intolerance however I find the same when eating a lot of sugar. It could be yeast related. Through experimentation I've found that the white 'gacky' sliced bread is particularly bad.

3) I don't think we are designed to eat modern wheat. I switched from beer (ale) to cider and find I have no morning after 'bowel' effects.

4) I avoid sourdough bread. Who am I kidding. Best bread in the world. My crack cocaine. Thankfully there are some awesome artisan bakers in Bath, UK. However when I buy a loaf, I commit to a 20+ mile cycle ride.

5) If I eat a carb rich meal, I will get hungry quicker. I can feel 'fuller' for longer by avoiding carbs. It makes me avoid snacks.

A lot of the above is about feeling mentally alert at work/home. In the winter it means I cook up big pots of high protein stew, freeze them and take them to work and zap them in the microwave. Summer is all about big boxes of salads, heavy on the meat/cheese/dressing.

At work we have lunchtime Dirty Burger Wednesdays where we grab nasty takeaway food :) Like I said it's not about being religious about not eating wheat, just generally trying to minimise intake. I know what a high carb diet makes me feel like.

One proviso. I cycle to work. The morning is almost a free wheel 2.5 mile down hill ride. The evening is a 2.5 mile climb. It used to be a real bitch. Now only the last 0.5 mile is a bit nasty.

>I switched from beer (ale) to cider and find I have no morning after 'bowel' effects.

I started having these problems about a year ago for no apparent reason. I'm going to have to give this a try, thanks!

When you say no fructose, that that mean that you don't eat any fruits?

I eat some fruit in moderation, but avoid juices and carbonated drinks which use high-fructose corn syrup.

IIRC Fructose is processed in a similar way to the way alcohol is processed in your system. It's not an energy source that can be used by your body without processing. I also believe it's one of those energy types that is readily stored as fat.

I read that the liver is the only organ that can process fructose directly. I tried taking honey before bed in order to avoid hangover. Seemed to work, but may have been placebo effect.

did you try not drinking before bed?

http://www.theonion.com/articles/man-blames-hangover-on-ever...

usually if I was aware enough to try honey I accompanied it with water.

Thanks, that helps!

Been doing IF every day since July 1, 2013. Before that I was eating slow-carb diet and had lost about 50lbs.

When I started doing IF, I was lifting pretty heavy and after the first week I had gained weight. I was pissed because I was hungry all the time it seemed, but I gained weight this week? Huh? Well, fast forward to now, and I put about 20 pounds since July 1, and yet I am not fatter. I am muscular. It's weird, and yes I was lifting, but fasting helped my body get from that chubby kid phase to, 'oh wow, I think I am almost ripped'. There are definitely some real benefits to fasting and no one will tell you that because they can't sell it to you in a pill.

Something really intriguing to me about fasting for 24hrs+ and then having to eat. For me, I crave healthy foods at that point and I also have the instinct to stuff my face and thus one meal/day works for that. It's tough to eat a bunch of crap when you are only eating once/day.

Finally, if you are interested in IF, I recommend reading up on Ori Hofmekler. He is the type of guy who's ideas are so crazy at first they are brushed off. Then science proves him right.

http://www.amazon.com/The-Warrior-Diet-Biological-Powerhouse...

I too only have 1 meal a day. Some days (few a month?) I cheat, mostly for social reasons. It's hard to refuse every lunch request.

Usually, though, I have an apple and cup of tea about 2PM. Dinner about 8. So I'm doing all my eating in a 6 hour window, fasting the other 18 hours, every day.

For lunch requests my go to excuse to people is that I am in the middle of a fast. Thus, I don't mind going to eat with them, I dont seem weird for eating healthy, and for whatever reason, people have been more understanding of the fasting excuse over, oooo I cant eat that.

But with cheating in general, I will move the hours of fast around. So if I do go to a lunch, I'll probably eat pretty damn big and then fast until 6-8 the next day, make a good dinner. It's funny how much you enjoy food when you learn how to eat.

I find it frustrating when people often discuss experience with 'intermittent fasting' without describing exactly what they mean. The term ranges over lots of approaches. I've seen it used to describe just 8 hours (perhaps every/most days) without food, to a full day or couple of days without food (perhaps every other day or once per week or two), to other things, as is the case here.

Fortunately, clicking through to another article in the series (http://www.bbc.co.uk/news/magazine-25498742) gives more details about what was tested here:

The food, during the [5-consecutive-day] period of the restricted diet, was designed to be highly nutritious. It consisted of plant-based soups, kale chips, a nutty bar, a herbal tea and an energy drink. The total number of calories, in five days, was about 2,500 - a little more than the average person consumes in one day. No additional food was allowed. For the rest of the month we were allowed a normal diet. The regime was repeated three times, followed by a control period, when we could eat anything.

8h without food wouldn't be intermittent fasting unless everyone does it when sleeping.

There is one diet type quite popular right now in fitness called Leangains which calls for about 16h of fasting and a 8h eating window (granted that you can reduce the eating window if you feel like it).

Some people even reduce the eating window to just one meal (warrior diet).

For nearly a year, I've been just having coffee with MCT oil in the morning, which pretty much keeps you satiated until 4 pm when I get a light "lunch" and then eat dinner around 9 pm. No hunger ever, no snacking, a few pound of weight loss even though I've increased my calories (get tons from the chunks of grass-fed cheese). Calorie counting is oversimplification of the complex metabolic processes in the human body and ignore major components such as hormones, thermogenesis, etc. Also, I don't get how sane people can accept that boosting your metabolism is healthier (like eating 5 times a day, exercising, etc.). It can't possibly be. Aging is a natural method of dealing the increasing cancer risk. Also, the faster your metabolism is, the sooner you will reach the Hayflick limit!

Isn't this just skipping breakfast?

In some ways it is skipping breakfast.

As vidarh mentionned, you also have to take into accounts macros (carbs/fat/proteins split) and having to eat 3500kcal in 2 meals can be tough sometimes (in the weekend i often do a 6h or so).

I've eaten that way pretty much all my life so it was easy for me to adapt (it mainly consisted of more proteins and alternating more carbs on workout days/more fat on rest days).

I made a quick calculator the other day if you want to see how it would look like http://vincent.is/working-on/leangains (github https://github.com/Keats/kCalculator if any angularjs dev want to review some code of an angular newbie!)

That is, in fact, one of the more common forms of IF: one or two days a week, don't eat until the evening meal (and, depending on your specific practice, perhaps eat only lightly then).

If you usually have long enough between meals that skipping breakfast gives you a 16h period without any food, then sure.

When people do leangains they also do tend to focus on getting more protein etc. though, which can turn the 8h eating window into a big ordeal - I struggle to get the calories I need in two meals on Leangains due to the amount of protein I take; I keep wanting to skip the second meal because I'm still so full.

Skipping breakfast and not eating anything after 8pm, typically.

This is not really a new thing. In India, fasting is a like a culture. More common with females though. Some of them fast like once every week. There are festivals which are based around fasting. Like Karvachauth, in which girls fast for their husbands etc (we are not very feminist yet). There are festivals during which people fast for straight 2-10 days! (chath, durga puja, somwari etc).

Even in Islam, during ramzaan people fast everyday for 30 days . They eat before dawn break and eat again after dusk.

Note that in ramadaan they also don't drink any water during the day; and many who can afford to, flip their schedule to sleep through the day so they can eat at night.

Also, according to superfreakonomics, this wreaks havoc on gestating babies. Seems like all harm and no benefit fasting (which, perhaps is the idea - Jewish fasting on Yom Kippur is specifically spoused to be a soul-torture/soul-searching experience - both translations are valid - although it is often not experienced as either)

It's also worth noting that typically people gain weight during Ramadan. They eat way more, richer food as it's a time of celebration and dehydration from the day.

http://latimesblogs.latimes.com/world_now/2012/07/cairo-the-...

Pregnant women are exempt from fasting during ramadan.

So are Jewish woman on Yom Kippur - but many of them still fast; enough to change date-of-birth distribution for Jews and health-of-newborns for Muslims.

Yup but that changed a lot these last years. Some women used to be "ashamed" of the fact that they couldn't fast like other people did, but now (with TV, more education, etc.) they know that Islam prohibits that (as it can endanger the baby) and it's bad for both them and their babies.

Orthodox, Coptic, and other pre-Great Schism Christians fast twice a week (Wednesdays and Fridays), where fasting is defined as eating only vegetables and grains. In addition, there are various other periods of fasting throughout the year, such as the 40 days before Pascha (Easter) and Christmas.

The intent of the fast isn't for health reasons, although from my own anecdotal experience it does seem to have healthful effects, such as sharpening the mind. The rules aren't set in stone but are an ideal for the purpose of cultivating self-discipline and a humble awareness of our limitations. If a person fasts from food but "consumes" their neighbor (through anger, jealousy, etc.), then the whole point of the fast has been missed.

The recommended practice in Islam is actually to fast two days a week, in addition to the month of ramadan.

A lot of the diets mentioned on this thread are a long way from the diet used in this article. Note it is not mentioned in the article, however it is mostly vegetables with some fish. That is a long way from 'chipotle'!!!

It is worth bearing in mind that a lot of things we consider to be food really does not want to be food. Grains want to be carried away by the wind to plant themselves somewhere else. Their ancestors invariably had toxins in them to dissuade any creatures (including us) from eating them.

Not one single animal, insect or fish has evolved specifically to be eaten. Hence the wide range of defensive measures most animals/insects/fish have to make sure that does not happen too often. Again, toxins come into play. As you move up the food chain so you get an accumulation of those toxins, hence we tend not to eat apex predators.

Compare and contrast with fruit. Fruit has evolved specifically to be eaten, particularly by primates. The idea being that we eat some fruit, wander off to somewhere new, have a dump, eject some seeds from the fruit complete with a handy amount of manure and water. Yep, those pesky plants tricked us into doing all of their work for them! They even managed to get us to cover up our leavings, thereby planting their seeds properly.

Our vision system co-evolved with fruit, we (as in primates) see in colour not because god wanted us to live in some world of puppies and rainbows but so we could eat fruit that is ripe and ready to eat. The plants, knowing that we were evolving colour vision, kindly evolved through some process of natural selection to produce fruit that kick in to 'eat me' colours when they are nice 'n' ripe.

With this colour coded system it is possible for plants to avoid waste. We (as in primates) only pick the ripe fruit, the stuff that is still green is identifiably no good to us so we leave it until it magically changes colour.

Obviously there came a time when grasslands took over and we had to leave the trees, learn to stand up and walk on two feet (so we could see over the grass) and find new meals to try. At this stage the cult of eating dead animals was borne, we adapted, but not that much, our intestines are still a million miles longer than that of a dog, we still have hands for nabbling fruit rather than vicious claws to rip apart stray wildebeest and we can still chew, as you need to do for fruit, in a way dogs don't do.

Much like how multi-vitamins are of dubious benefit to you, so it is with fructose. Sugars in fruit are fine, nobody has died of diabetes due to eating too many apples. The 'fibre' is an important part of it, you need 'fibre' if you are to consume sucrose.

The problem with diet in America is corn. There is nothing edible about corn grown in America today unless it has been processed by an industrial process or another animal first. All of those corn-stuffed animals Americans eat get killed before the corn kills them. If Americans are not careful they will be remembered as 'the corn people' like some of those American Indian tribes that tried and failed to build corn-based civilisations in pre-Columbian times.

> It is worth bearing in mind that a lot of things we consider to be food really does not want to be food.

What they want is irrelevant. As they evolved to avoid being eaten, so we evolved to be able to obtains, eat and digest it. It's not a one-sided process of providing us with a ready made menu.

> At this stage the cult of eating dead animals was borne

Why do you assume we did not eat animals "in the trees"? Is there any evidence to support that? Chimps eat meat on occasion, for example, and when they do the pack literally tears the victim apart.

And describing it as a "cult" is ridiculous. It became important because it is an immense source of nutrients, and available in many places where surviving on available plants/fruits was near impossible prior to the development of extensive trade. The ability to eat and digest meat provided us with yet another evolutionary advantage over many other animals.

> We (as in primates) only pick the ripe fruit, the stuff that is still green is identifiably no good to us

There's plenty of fruit that's green when it is ripe, and plenty that is a different colour than green for a long time before it is ripe.

> we still have hands for nabbling fruit rather than vicious claws to rip apart stray wildebeest

Which have proved superior in providing means for killing animals? Our hands can hold and wield weapons. Which approach to eating meat is better: Tearing apart raw meat, or cooking it? You seem to assume that we are not well adapted to handling our new menu entries and/or that these features somehow means we're better adapted to fruit just because we haven't taken on the characteristics of animals that are terribly limited in their abilities.

Spot on critique. Two additions:

What about pure carnivores? Surely their food doesn't want to be food, but carnivores do just fine.

While I agree that the amount of corn we eat is absurd, to call it inedible is ludicrous. Raw corn on the cob is plenty edible, and sweet corn is quite tasty, although that's admittedly not what's grown on large corn plantations.

True, in the classic 'cheetah chasing wildebeest' scenario the the wildebeest is not 'chemically defended' and the cat enjoys his dinner. However, we aren't pure carnivores are we? Our taste buds are different as is our gut flora, our saliva has enzymes in it plus we have a lengthy intestine. Sure we can eat wildebeest - raw - but we would have to sit around all day - cat style - to have it digest. Due to the intestine length our 'wildebeest on toast' would start to rot inside us whereas the cat would not have that problem. Hence we cook animals and use the word 'meat'.

98% of the corn grown in the USA is field corn, grown for its starch content. You cannot eat this stuff and enjoy doing so. You need something tantamount to an oil refinery to make it edible or a distillery to make it drinkable.

The corn you are thinking of - the nice sweetcorn in the supermarket - is from a different variety, it is grown for the sugar content, not the starch content.

Essentially field corn is a chemical feedstock, it can be used for many, many things - which is great. However, look at those ingredient labels in the U.S.A. and, after a while, question whether you are eating a great deal of stuff that is not corn-derived. HFCS is obvious, 'xanthan gum' is not so obvious.