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Comment by gtrubetskoy | Hacker News Reader

What's interesting is that most of the population of this planet does not even realize that glucose is not the only source of energy and that we can be powered entirely by beta-hydroxybutyrate (which comes from fats); our carbohydrate requirement is zero because our body can synthesize all the glucose it needs.

Here is a pretty good and scientific talk about what is happening (warning > 1 hour long): https://www.youtube.com/watch?v=dBnniua6-oM

Edit: just noticed this y/t has already been cited in another comment - evermore reason to pay attention to it :)

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There are costs to gluconeogenesis (glucose via protein catabolism), kidney issues to name one (deamination producing ammonia). The body does not synthesize glucose from fatty acids (beta-oxidation occurs producing aceytl-coA in the mitochondria, thus producing energy, but aceytl-CoA cannot be converted upwards in the pathway to glucose). A small amount of glucose can/does get created from glycerol.

Nutrition recommendations up to this point still recommend high ratio of carbs (45-65% of kcals) because they are the most direct metabolic pathway. Also incredibly important for gut health is fiber, which is a complex carbohydrate (and prebiotic). The concern of carbs is non-complex ones as a high percentage of intake.

They have found that the brain runs on ketones (for a long time it was thought that it required glucose specifically) but long term research is non-existent. So yes, the body can live off of "no carbs", but stating that our carbohydrate requirement is zero is just false according to the literature and nutritional history of the majority of humans.

So you're saying HN comments are not a good source of my daily nutritional information?

:) Like everything else in life, nutrition as a science is incredibly more complicated than we want to believe or describe. A seriously good place to start is MyPlate (their nutrition AND physical activity recommendations).

I'm always skeptical when I hear "Nutrition recommendations" because it implies some sort of authority. Nutrition recommendations from who? The USDA?

It's worth reading the history of the food pyramid. Here's a quote from wikipedia:

"The first chart suggested to the USDA by nutritional experts in 1992 featured fruits and vegetables as the biggest group, not breads. This chart was overturned at the hand of special interests in the grain, meat, and dairy industries, all of which are heavily subsidized by the USDA.[10] If Americans followed the chart suggested, they would buy much less meat, milk, and bread. On the other hand, if they ate as the revised chart suggested, it "could lead to an epidemic of obesity and diabetes," as original composer of the food Pyramid, Louise Light warned. "

I know from a personal standpoint, once I removed refined carbohydrates from my diet I dropped 25 pounds in two months (without bothering to excersize.) So the idea that somehow the diet that made me fat is somehow the "good" diet because the USDA says so strikes me as being silly.

Skepticism is important for any advice. MyPlate/USDA dietary guidelines are updated often, based on all the research and debunking that has happened before and since 1992. As I mentioned in another comment, it's a good place to start for most people. There is going to be some influences affecting their recommendations but most people can benefit from the overall approach.

A diet with high carbs should be mostly complex carbs. There is no minimum refined carb recommendation. The only recommendation is to limit added sugars to <10% of daily kcals. That recommendation may be reduced further in later revisions.

I think we both agree that complex carbs are better than refined ones, and there are foods that are somewhat heavy in carbohydrates that are still good for you (kale, for instance).

I'm super skeptical that 45-65% of diet being carbohydrates is healthy though. Unlike proteins and fats carbohydrates don't have much nutritional value other than being useful for creating glucose. Since your body can synthesize glucose anyway, you don't really need that much. In terms of fiber, you can get that from vegetables. I don't necessarily think you have to cut out carbs completely and go on ketosis, but of all the major macronutrients carbs are the least useful, so it seems odd that they should be the vast majority of the diet, especially when we've known for at least a hundred years that carbohydrates are fattening. (I'm amused when people act like ketogenic diets are "new" -- historically high fat/low carb diets were common. And historically we didn't have an obesity problem.)

"the body can synthesize glucose" is a horribly misleading statement. The body can create glucose only by destroying protein and the amount it can create is limited by the buildup of toxic waste the process leaves behind. It's absolutely not the same thing as the body synthesizing vitamin A from carotene. You will be much better off eating carbohydrates, and 45% may be still too little.

I've read a book[1] -- by an actual doctor -- saying the exact opposite. If you think about it from an evolutionary standpoint, our ancestors would have had many times when food accessibility was scarce and they would have needed to maintain their strength through a long fast. An animal that burned muscle/protein over fat is an animal that wouldn't have survived long, that would be a terrible evolutionary disadvantage. The design of our body isn't stupid -- we store fat for a reason, so that we can burn it in times when food is scarce. Burning fat for energy is both normal and totally healthy.

From a personal standpoint, I barely eat any carbs and I've lost zero strength despite dropping 25 pounds. Apparently the diet that has made me thinner and increased my energy and mental clarity is the "dangerous" one, and the diet that has made everyone obese is "healthy" and "balanced".

[1] The Obesity Code by Dr. Jason Fung

Fats do not become glucose (with the exception of the glycerol from triglycerides...a minute amount of the total kcals from one trig) but they do become energy. The majority of energy is in fatty acids which have no pathway to glucose.

For example, it is believed that when we sleep our energy comes from fats. We are not doing anything exerting, so the process of (fat catabolism -> energy) >= energy needs. The brain needs glucose however, so it gets it from glycogen catabolism or protein catabolism (gluconeogenesis).

Edit: For some reason I cannot reply to the comment below. The recommendation is 45-65% based upon individual need. I've mentioned elsewhere in this thread that the brain can use ketone bodies.

I disagree that glucose = obesity as you seem to see it. Many, many things (nutrition, PA, stress, hormone issues, etc) are related to obesity.

A lot of what you emphasize is related to the lack of physical activity that the population no longer gets. If we truly want to solve obesity, it takes adjustments to diet and consistent purposeful physical activity. There's a lot that can be done with nutrition, but continuing our highly sedentary ways will always have consequences for health that nutrition alone will not completely solve.

Ketone bodies can be used by the brain. It prefers glucose, but you don't absolutely need it.

Lets say for a second you're right and you need glucose, though. 65% is a really high number, and we basically know exactly what it leads to (obesity).

Stop spreading misinformation. 65% is well within historical norms. People commonly ate that much or more, oils and meat used to be expensive.

I'm only giving advice that I've personally tried myself, and have seen it work. I actually have a coherent theory for why people get fat, you just have... anger

I think it's important to separate health and obesity when considering exercise. A large body of evidence shows us that exercise makes you healthy. A smaller body of evidence shows that exercise helps prevent obesity. But there is virtually no evidence that shows exercise has a large part to play in curing obesity.

I'm not comfortable with the word "designed." There is evolutionary adaptation, there is no design.

Would you have lost the same 25lbs. if you had just eaten less? In other words, does it really matter that you cut out carbs only? Are you chowing down on bacon and steaks?

A large percentage of our dietary need is strictly for energy (via glucose). Carbohydrates are most efficient over fats or protein to fulfill this need, among other needs like fiber intake. Complex ones work best, not only for sustained energy but other benefits as well.

Yes we have needs for micronutrients, which are acquired from all of the macros. If your diet is truly varied, balanced, and adequate (in all three macro categories) on a regular basis you will likely not be significantly deficient in micros.

Ok but, the only reason you would care about getting energy super efficiently/quickly is if you're an athlete. Also while glucose is certainly easier to burn, I've seen evidence that ketones are actually a better source of energy. Since we have an obesity epidemic, and the vast majority of (fat) people are on the diet you're proposing, I would suggest that energy efficiency is not exactly a high priority for most people. If we know that carbohydrates will cause weight gain (not just in humans, but in animals too -- there's a reason why they feed cattle grain and not grass), and we know that the biggest health problem we have right now is obesity, suggesting that people should eat a lot of carbohydrates seems like terrible advice.

And if you're going to suggest that the solution there is to decrease caloric intake, I also think that's bad advice. We know, from type 1 diabetes, that your body doesn't store fat if insulin isn't present. Certain foods have a much stronger insulin response than others, and not surprisingly carbohydrates have a much stronger insulin response than fats. IE, the notion that all calories are equal is not supportable by the scientific evidence. So if the culprit is insulin response, it would make much more sense to adjust what you eat and when you eat it, instead of measuring a number (calories) that isn't that useful anyway.

I disagree that the vast majority of people are following the dietary guidelines (they aren't just AMDRs) I base my assertions from. However, unless you/I present evidence for either case, it's a non-starter.

You're ignoring the complexities of insulin/components of a healthy diet/physical activity regarding carbohydrates. Technically, you could just eat only protein and survive. Doesn't mean this is the best advice and without many complications.

Of course carbs have higher insulin response as insulin regulates blood sugar uptake. Fats dont produce sugar, therefore insulin is unrelated. And many, many things cause weight gain, including fat intake for some.

Current guidelines allow for up to 35% of total kcals to be fats, with minimal/no risks. This encourages plenty of consumption of fats for energy. Perhaps if we continue our extremely sedentary ways then this will be raised higher in the future.

Obese people are obese because they eat--A LOT. I had a relative like that. The amount of food put away was epic.

I used to eat one (small) meal a day and I got fat. And then I switched my diet and I got not fat. I don't know why people make this stuff so personal, body chemistry is complicated and it's not that weird that certain foods are better than others.

Certain foods can be better than others, but the basic tenet "eat less than you need to power yourself" seems like it should be a consistent formula for anyone who adheres to the first law of thermodynamics.

I (and presumably many others) have used it with notable success, so when I see a data point that suggests it's not a valid approach, I immediately question the validity of that data point.

I've switched to a low carb / high protein / high fat diet and it's great. I'm eating lots of food and losing weight along the way. Each Saturday is cheat day and I eat anything I want.

Breaking the sugar / carbs dependency was really difficult for the first weeks but now I'm "fat adapted" as they call it.

I've been doing this diet for a year or so and broken it a few times for weeks at a time. Getting back was super easy and I didn't gain much weight. In 2016 I've lost more than 20 kilos, or about 6 belt notches. I even had to buy a new smaller belt.

If you want to know more about this look for the Atkins diet, 4 hour body diet, keto diet, etc. Those are all variations on the same idea of reducing or eliminating carbs from your diet.

I didnt' watch the video yet. But do you need to be "in ketosis" to benefit from this energy source?

How difficult is it to incorporate this in your diet? And is it expensive?

> I didnt' watch the video yet. But do you need to be "in ketosis" to benefit from this energy source?

Your body will handle that naturally. If it doesn't have enough of resource A, it'll try resource B, then C, ... It happens automatically.

I did Keto for a month in September. It requires a good deal of self-control to stick to it (you'll quickly realize that only about 1% of the grocery store is food you can eat on Keto - resisting that temptation constantly is a trial) but it's not particularly expensive. You do have to be "in ketosis" to get the full benefits of Keto, but I've also found that just sticking to a low carb diet (under 100 carbs p/d) is a good start to ease into it. For Keto you will need to stay under 50...some people stay under 20.

I lost about 15 lbs during the process and my diet mostly consisted of salads with lots of chicken + cheese + high fat dressing. I was a vegan before I switched to Keto so eating my veggies was not difficult, but some of my friends struggled to keep a "healthy" diet during the process.

The most difficulty you will have doing Keto is your own self-control. Finding recipes & food to buy is easy.

Keto was the only diet I could lose weight with. One thing a lot of other diet plans ignore is satiety. If you are hungry or crave food, it is basically an addiction. You will not stop till satieted. Sugars and starches spike glucose levels and thus trigger insulin responses which puts one back in a hungry state.

Yes we evolve from a common ancestor with the monkey, which used to eat mainly fruit, hence sugar.

Fruit tends to be healthy because the sugar (fructose) is wrapped in protein and fiber. In other words, it's very very distilled. That's the reason why eating an orange is a lot healthier than drinking orange juice. But we do know that fructose is VERY bad for you (high fructose corn syrup is much worse than sucrose alone).

I don't think there exists any evidence that high fructose corn syrup is much worse than sucrose. They are pretty close to the same thing.

HFCS is 45-58% glucose, and 42-55% fructose, and sugar is 50% glucose and 50% fructose. There is one more bond in sugar, but enzymes in your gut break that bond apart very quickly.

Well, I'm not exactly saying your should eat a bunch of sucrose either, so I might have overstepped by saying it's MUCH worse. But I do think the evidence points to fructose not being good for you, and it's certainly not better than other sugars.

Why are you lying like that? Are you trying to hurt people?

Huh? I'm a liar for saying "sugar is bad and certain sugars are worse"?

So what is the evidence for fructose being bad for us?

Fructose can only be metabolized by the liver (whereas glucose is useful in the rest of the body) so in terms of generating energy it's not particularly useful, but your liver has to deal with it. If your liver gets more fructose than it can use, it turns it into fat which is stored on the liver, leading to fatty liver disease and insulin resistance (same thing with alcohol).

You've stated all of that as fact, when there's some debate about some of it.

https://www.gov.uk/government/uploads/system/uploads/attachm...

Page 209 onwards.

It's worth reading those few pages, but here are some snippets.

> Products sweetened with HFCS are not necessarily significantly higher in fructose than foods sweetened with sucrose as HFCS has a similar composition to sucrose, which is 50% glucose and 50% fructose.

> The body absorbs free fructose and glucose, or the same sugars derived from sucrose and HFCS, in exactly the same way. Therefore it appears unlikely that fructose, as consumed as a component of most HFCS or other glucose-fructose syrups, causes metabolic abnormalities or promotes weight gain more than other sugars consumed in an isocaloric diet (Klurfeld et al., 2013).

Especially this:

> A3.10 Therefore on balance, it is considered that there is insufficient evidence to demonstrate that fructose intake, at levels consumed in the normal UK diet, leads to adverse health outcomes independent of any effects related to its presence as a component of total and free sugars.

Well look, with something as complicated as metabolism you're likely to find evidence that goes both ways, but I don't think any sane doctor would object to "eat less sugar", whether that be fructose or glucose or whatever. From what I've read, I think fructose is worse for you, but I'm not going to claim that with 100% certainly. I will claim you'll be better off not eating sugar regardless.

I didn't ask you to repeat yourself, I asked for evidence confirming what you said.

If your argument is that "eating sugar is good for you", I encourage you to eat all the sugar you like. It'll be a fun science experiment. Let us know how it turns out.

What happened when you tried to eat more sugar?

I'm also simply tired of the excuses fat people make "Muh HFCS did this." Yeah, that and drinking 4 2 liters a day.

I don't think it's the distilled part that is important. I doubt the quantity is as important as the other nutriments you get that makes your body functions well enough so that you can benefit from all the sugar.

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