New report on the cellular effects of a calorie-restricted diet in rats
salk.edu
salk.edu
Study after study and clinical experience shows that low calorie diets are really hard for humans “in the wild” to maintain in practice. People who are on them constantly complain of hunger (in the mid-20th century these were actually called “semi-starvation” diets), and go back to their previous weight as soon as they are done. That’s why a lot of modern dieting has oriented around low carb / high fat because it means that you get enough calories, but the composition of your macronutrients causes you to lose weight. You don’t have to go as low as Keto to get these effects (that’s 5-10% carbs) and certainly don’t need to entirely cut out fruit, etc. And the results have been observed clinically for 100+ years.
This, however, hasn’t prevented academic nutritionist after academic nutritionist from pushing these narratives without any clinical experience. Can you imagine being at least a little hungry for 20 years... the equivalent time span in humans to get the effect reserved here in rats? That’s insane. And, more bluntly, probably not doable.
If you’re skeptical of this try dropping your caloric intake by 30% for two weeks and tell me how you feel :)
You loose weight, because you burn your excess fat. Without restricting your intake, there is no reason for your body to burn your fat reserves and that’s why you won’t loose weight just with low carb and same total calories.
(You may loose some water, but not fat).
On a ketogenic diet, your body is constantly using fat as fuel, which makes it easier to eat less calories and be less hungry. Also ditching carbs prevents insulin spikes, which impact a lot how you feel and act.
I lost +30kg with restricting my calory intake by ~25% (calculated on the energy value of the fat loss per month) and keto helped me to not feel hungry and also skip a meal or two without any impact on my energy level.
If you think about how incredibly complicated things like nutrients and proteins are, and how insanely complicated the body is, it makes sense. We've evolved so that we can eat almost anything, but that doesn't mean that we should eat anything. The evidence seems to point towards carbohydrates being something that should be eaten when there's a large energy demand and otherwise should be kept low.
"risk for obesity is primarily determined by total calorie intake"
The macro nutrients certainly matter in the details, but not so much in the overall picture. It does mostly work like a gas tank, and the energy content in good is literally measured in [kJ].
Fat has a lot of stored energy, why on the planet, do people believe the body is able to create and store energy out of thin air?
And it exactly works the opposite way, the body will use the stored energy in the fat if there's not alternative.
Please don't use dismissive internet tropes like that on HN. It's of course fine to cite a study, but no single study is "Science".
Yes there are subtleties around actual macronutrient composition and gut flora, but the effect appears to be minimal. Find a keto person eating 5000 calories of bacon per day and I guarantee they’re not losing weight.
For what it’s worth: I’m a big fan of keto for cuts.
Personal anecdote: my bread tolerance dropped dramatically on a 6 month keto stint. Sandwiches were gross there's just Soo much bread! Yuck! Then I got used to it again but now I stick with mostly rice/beans and have maintained my weight loss which is great
It's perhaps not as easy as a yes/no list, but 40% is very easy to figure out from the nutrition label:
max_carbs = calories x 1 g carbs / 10 calories
For example, a Sausage McMuffin w/Egg at McD is 480 calories, so as long as it has no more than 48 g of carbs, it's OK. (It has 28 g).
Make every item on your meal satisfy the 40% criteria, and the meal as a whole will.
Slightly up the effort scale, you can keep a running total of how much you are over or under for the day. Say you are going to get the Sausage McMuffin w/Egg for breakfast. That puts you 20 g of carb ahead. How about adding some McD Donut Sticks to the meal? 280 calories, 33 g of carb. That's 5 g too many carbs for the item to be 40%. But the McMuffin is putting you 20 g ahead, so losing 5 g won't mess up your overall meal. Go ahead and have those Donut Sticks if you like them.
Specifically, we store energy in adipose tissue in the form of body fat after a meal (think of it like storing data on disk) and then when we are low on energy we burn that fat (load that data “in-memory”). However, a lot regulates when we burn fat. Blood sugar and insulin levels signal to the body not to burn fat and those come directly from carbohydrates. Additionally, carbohydrates are the initial energy source that is turned to fat. So with no carbs all your body knows how to do is burn fat for energy, and no additional intake of carbs means that there is no excess energy to store as fat to begin with. So, actually, even with a 5000 calorie diet you might see some weight loss... because your body has literally nothing (no carbs) to store as fat.
However, keto and low carb diets do have the benefit of the fact that they are entirely sustainable (unless you’re really addicted to bread) so I agree in that way they are behavioral :P
And fat is the first thing to get stored when there's an insulin spike, not to mention the carbs+fat combination is the thing that creates insulin resistance exactly because of the fat messing everything up.
So I'm thinking, and please correct me if I'm wrong, that you are just repeating some keto "truth" that does not really make sense. Because when I googled that, the only sources were pretty much some keto promoting pages.
I hear the "energy in-energy out" being dismissed like this often, and while I do agree with you that our bodies are more complex than that, I want to say that in practice this adage more or less just works, indeed to the degree that it's valuable to have in common knowledge to inspire folks to lose fat.
Particularly, if you want to lose fat, you reduce your caloric intake (and what you are consuming, shoot for higher protein intake and lower carb intake). In addition to this, do some aerobic exercises. This is really it. If you do this you're nearly guaranteed to lose fat. I did this, my peers did this, it's really simple, the only hard part is finding the motivation to start and having faithful long-term committal to a routine.
Add extra activity, and the natural effect will be an increased appetite that'll nudge you to eat more calories - and it's not a given the effect of that extra activity will be a calorie deficit, the increase in appetite can easily be more than what you spent in those exercises.
If you try to reduce caloric intake, that's a very different beast than actually reducing caloric intake - if you try to reduce caloric intake by skipping carbs at lunch, it can result in reduced activity (so less calories out) and a strong nudge to "cheat" at other meals or snacks; and again it's plausible to get to a situation where the unintended compensation is larger (and opposite) than the behavior modification that you made.
That is the problem with the "energy in-energy out" model - one does not simply change the 'energy in' or 'energy out' part and expect that other things will stay constant either magically or through sheer willpower.
I like to think of a silly extreme. If I drink a gallon of gasoline, I've technically consumed what, a billion calories? But I won't gain a single gram.[1] Why? There's no metabolic pathway to convert gasoline to ATP.
If you take that silly example and moderate it, you can see how different factors, including genetics, gut flora, adaptation, etc could affect what is even processed and thus part of the "in" variable.
More concrete, well known examples:
- If you consume 5000 calories of just protein, the metabolic pathway to convert to lipids is extremely inefficient. You will mostly excrete the excess. - Similar with pure ethanol. If you drank just alcohol (and nothing else), there is no metabolic pathway to convert this to fat. - Even carbs. If you just ate 5000 calories of pure carbs, de novo lipogenesis (metabolic pathway for carbs -> fat) is rather inefficient. You will gain weight but less than the 5000 - expenditure. A lot of it is burnt off as heat. - Sadly, for ketoers: the dietary fat to lipid pathway is extremely efficient. Almost 90% of excess will be stored as fat.[2]
See a pattern here? The reality of the typical diet is that we don't just eat one macronutrient. We mix them. And specific ratios are what make food hyper palatable and thus so easy to overeat. Once you start mixing things up, it basically - and I mean basically - comes down to calories in vs calories out.
[1] In fact, I would likely die. [2] As another commenter mentioned, there was one guy who just ate fat and well in excess of his BMR and apparently lost weight. I'm skeptical, but could believe it simply because it follows the trend: consuming just one can "bend" the rules.
https://bodyrecomposition.com/fat-loss/how-we-get-fat.html/
Never mind the clickbait-ey domain. Lyle McDonald is a nutrition authority and well respected. Though on forums he’s self-admittedly volatile.
21 years ago (I mean this literally, I read him then) he was touting on MFW how the discovery of leptin was going to render dieting obsolete in less than a decade.
He has a lot of good content, but it's always decisive, even when some is rong.
Anecdata, everyone's favorite - I've seen someone gain no weight eating near 100% protein, while way over their TDEE. Kid you not, 4000 kcal of lean protein and mustard.
Also morbidly, you've got alcoholics (spirits), also traditionally under weight while consuming far in excess of their TDEE in ethanol (7 kcal per gram).
So some of it can be tested in the field!
26579 kcal
Or you replace high calorie food with food that does not have much calories. Like lettuce salad, which has like 17kcal. Then you would need to eat over 10kg lettuce salad to get the required 2000 kcal. That is hard to do and hard to overeat
I’ve done so for three weeks this month because of money issue (only one real very balanced meal a day, few biscuits on the evening) while also increasing physical exercise (walking between 5 to 7km a day) and I plan to adopt a similar diet for a longer time. The hunger was not very hard the manage and I even felt better than before. Overall I feel I have been more productive than usual. I also have sleep issue but I felt consistently less sleepy during the day than previously when eating a lot.
But think of how that discomfort will make time pass more slowly. It'll be like adding two years to your life!
I think a better way to frame a healthy diet is that you should aim to follow all three and realize that they (obviously) help each other work. These are collaborative orientations, not competitive.
You can control i) what you eat (low carb/high fat), ii) when you eat (intermittent fasting), and iii) how much you eat (low calories).
You should be following at least one of them at all times, two of them often, all three of them sometimes.
Carbs are fuel, if you're not exercising you don't need much fuel, and can probably run on your fat reserves. I'm on a high carb, high protein, low fat diet now, which wouldn't be viable if I stop exercising.
Recently I have been pondering how we should eat if higher protein increases all-cause mortality and higher carb diets increase all-cause mortality, so I've come up with my seasonality hypothesis: basically we would experience periods of lower carb or lower protein diets historically, which would engage each of these various beneficial pathways we have.
For instance, and this is my hypothesis: we wouldn't eat wooly mammoth for breakfast lunch and dinner every day, we would eat nothing but it for three days, once a month. Dense carbs would come sporadically ("yay, we found a bee hive" twice a year) and fruits (carbs) would blossom in either only spring or fall.
Evolution doesn't generally optimize for longevity, it only optimizes for reproduction. The lifespan of most animals in the wild is much shorter than what can be achieved with a carefully controlled diet.
Granted it is a very different niche in the ecosystem but it hints that it is a matter of self-perpetuation where longer lifespan in this case is a side effect.
The best I've ever felt was keto, the easiest for me to adhere to was calorie tracking. It's marginally harder if you eat out a lot, but if you cook for yourself and can throw everything on a food scale for a week or so until you get an idea of what's servings of your most commonly-eaten foods looks like, tracking calories made losing weight for me and reducing my daily eating almost comically easy. There's a switch in my brain somewhere that works really well when I have to enter the calories of everything that goes in my mouth into an app....suddenly that cookie or those chips that were so hard to resist aren't a thing for me at all....my brain manages to yell "200 calories for THAT?? Nope." I found myself eating more at the end of the day just to hit my total calories and macros.
I found I can't just decide never again to eat the things I like and never again feel sated. Feeling hungry constantly isn't exactly my idea for the rest of my life.
Alternate day fasting lets me survive a day with no calories knowing that the next day I can be sated and eat (almost) whatever I want.
I have also found that when I eat every other day I put much more attention to what I eat on those days -- I mean, if I just did not eat yesterday and I won't eat tomorrow I want to eat well today. Even if I am going to eat sweets -- I will try to go for something better and not feed myself with garbage.
I also found that alternate day fasting is good willpower training. Being able to restrict myself from eating for an entire day somehow trains me to be better at other things that require willpower.
When not eating I would not eat or drink anything that has any calories in it. I typically drink water, black coffee or green tea.
I have also tried longer fasts from time to time (2-7 days typically, 2 weeks once) and then I would supplement with vitamins, l-tryptophan and lean broth/bone broth in moderate quantities (a cup a day), just for safety and general well-being (l-tryptophan is precursor to serotonin and mildly anti-depressant).
Intermittent fasting is hard at the beginning but after about 2 weeks I get used to new regime. It seems it is the same every time I start it anew. It might be getting easier but I think that's because I already know what to expect.
Also, when intermittent fasting it is much easier to start longer fast. I find, when fasting for more than 2 days first two days to be the hardest.
What I've discovered doing 72 hour fasts is that what I eat when I refeed matters a lot less than when I'm eating throughout the day. Keto made a big difference in my initial weight loss journey, but I find it to be somewhat miserable for maintenance. Yet, with fasting at least 48 hours, I discovered that the macro composition matters a lot less in relation to ketosis. In my eating window, I can eat rice, fruit, etc., and it will knock me out of ketosis for a short while but I'll usually be right back in ketosis between 24 and 48 hours from then. I feel much better in general getting a small amount of calories in, and it hasn't significantly effected my weight loss. In fact, when I was sick a few weeks ago, I stopped fasting and basically ate berries all week. The following week, I went back into a 72 hour fasting routine and still managed to lose a few pounds from where I was at before I got sick.
Put simply, I think the longer a fast is, the less that the need for keto matters. Keto combined with IF can work for a lot of people, and in a lot of ways they are complimentary in their benefits, but people can also tip the balance in favor of either more keto or more fasting and find their own combination that achieves their goals.
I subscribe to the church of keto / slow carb in broad strokes. I think there is a hormonal element that we don’t fully appreciate that relates to our ability to lose weight effectively.
My frustration with pure calories in / calories out is the rumination I do with how much calories we really extract from certain foods. I am convinced (as some science agrees) 100 calories of sugar and 100 calories of bacon aren’t handled the same. I also wonder about how some people must have faster digestive systems and if it moves through faster are you still extracting the same calories as someone else...
That said, how calories are measured is from an average approximation. It is true that different people may yield slightly more or less calories from the same foods. Calories are what your body extracts from the food post digestion.
That said, I've never seen strong indicators that the maximum and minimum are that far apart. So it could be that you are a huge outlier and your body extracts way more calories from food A then the average person, or way less. But I think those chances are slim, that is, for you to be such an outlier.
E.g. if we imagine running this on humans, are we talking about a BMI of 20, or 16?
I wonder if there's an intersection, e.g. without adjusting your eating habits, exercise results in an effectively calorie-restricted diet?
If there is no intersection, I wonder which is more valuable than the other? Not much exercise is going to be happening on a starvation diet.
this may or may not generalize.
Roughly
- worm: 5x longer lifespan by fasting
- mouse: 50% longer
- dog: 10% longer
- human: 1-2% longer
I'd be interested to hear support or refutations of this. It seems like something that should be pretty well studied by now.
I occasionally cut calories to lose weight or train my metabolism to be "ready" for emergency situations (which was honestly camping or going broke, not exactly military excursions), but in my experience it basically felt like death. Like I could feel my body catabolizing muscle and I had flu-like symptoms if I took it too far for too many weeks.
Anecdotally, my parents' boomer generation felt that bodybuilding was generally a waste of time. If you watch old movies from the 60s and 70s, people were especially lean. And then unfortunately juicers in the 70s, 80s and 90s ruined the reputation of bodybuilding so everyone figured that being strong meant taking steroids. It's only been in the last 5-10 years or so that I've noticed a resurgence in natural bodybuilding (check out Jeff Nippard, Steve Cook and Mike O'Hearn for examples of what's possible natty).
So personally I really feel that lifting weights from about 15-16 years of age for life probably replicates many of the health effects of calorie restriction. Like, Arnold Schwarzenegger did some of his best work in his 40s when he was in better shape than most people in their 20s. Many athletes in their 70s and 80s look like they're 50.
An untrained human bench presses about 100 pounds. When I was growing up, a 300 pound bench was considered mastery. Today with YouTube and better workout programs and supplements, that's probably 400-500 pounds. I personally would choose to have 3-5 times average strength (anything above 4 is metahuman IMHO) rather than spend my life at a withered calorie restricted strength of 1/2.
Of course ethically, it would be better for the planet if nobody worked out I guess. That's a separate discussion though, and I feel that some of the downside could be alleviated if the extra calories came from relatively benign sources like rice and beans. So my question is, is this all just vanity? Or would a diet/exercise approach be comparable to calorie restriction?
I started lifting at 21 after 4 years of college drinking. I've been lifting for 20 years, all natty, but it was a struggle to make gains. Meanwhile I've met 18-19 year olds at my gym benching, squatting and deadlifting the same weight as me because they simply have more testosterone.
It turns out that literally all that matters in bodybuilding is consistency and periodicity. Mike O'Hearn is so strong primarily because as a celebrity, he had access to all the best food and supplements and never stopped training. He also had Robby Robinson, who introduced him to connective tissue training by alternating weeks of 2-3 sets of 12 with 7 sets of 3 using a full range of motion. The standard 8-12 rep workout pitched by gyms is only for hypertrophy and unfortunately is the worst for strength and power that I know of.
My feeling is that Mike MAY have dabbled in steroids early in his career, but there's no way to prove it. He almost certainly took testosterone boosters like horny goat weed or Robbie's TestoFuel during his 30s and 40s. And I guarantee that he has tried every supplement there is so he knows exactly how to get the coveted "dry" look that typically only people on performance enhancing drugs achieve. I've seen him eating tupperwares of just meat in his videos, and he has talked about eating several pounds of fruit before bed, so I think his diet also isn't typical. So to me, he is the gold standard of natural lifter, even though I'm only 70% sure that he never did steroids.
Incidentally, I also feel that most of Arnold's numbers were achievable individually without steroids, except his 22.5" arms, 57" chest and 27" shoulder span. Those would probably be about 20-21", 52" and 24" respectively for someone with the right genetics. My thighs for example are the same size as his, and Mike's are quite a bit bigger than either of ours. But most people can only get to 19" biceps without drugs.
I've already said too much about this, but if anyone wants to really gain mass as a natty, the only way that worked for me was to eat at least 4000 calories (4-5 full meals) per day, plan to gain at least 30 pounds over your target weight (bench press gains are proportional to body weight gains), and then DO NOT use a 5 day bro split. The best workout I found was a 4 day split of: legs, chest and bis, back and tris, shoulders. Also known as a push-pull workout. Unfortunately I didn't know about periodicity, so I did 5x5 over longer than 6 weeks cycles and wound up with injuries and tendonitis (so watch your elbows). Today I can only do 3-4 week cycles with a 1 week deload, alternating grips frequently with lots of narrow/wide and reverses to prevent injury.
I'm curious to hear other perspectives on this though.
What it should have been: Are you a lab rat? Eat less, live longer! Salk scientists show how caloric restriction prevents negative effects of aging in cells of rats
If you eat 30% less than you should calories do you not eventually get so thin that you die from under nutrition?
can i skip breakfast and eat whatever i want for 6-8 hours, ala IF?
does the window of consumption not matter, and i just need to eat fewer calories on the day?
For me, simply, it's easier to eat less calories if I intermittent fast. For some reason, if I don't eat breakfast or lunch, I find my hunger is actually sometimes lower, and I don't need to eat a bigger dinner to make up for it.
Certainly eating low-g.i\high-carb foods seems to make me get hungry again very easily.
I also had really good luck with keto, and sometimes a combination of both.
I believe the reason is something to do with blood sugar and insulin not spiking as much, but I'm not a biologist in the slightest.
Here's a guide that's not bad. https://www.healthline.com/nutrition/intermittent-fasting-gu...
IMO, nutrition is such a complex topic and I feel like we have only begun to start peeling the layers.
As an aside, did you know that the saying "Breakfast is the most important meal of the day" was invented by the founders of the Kellogs cereal?
There's nothing destructive about fasting, as long as the person isn't starving. A lot of people confuse fasting with starvation, but they're not the same thing. Body fat is food. As long as you have fat to burn, you're not starving. Few people are going to starve doing even 72 hour long fasts. The human body just doesn't require that many nutrients on an hourly basis. You won't die or get hurt by not eating kale for a few days.
It was common wisdom that skipping a meal was destructive, but it's becoming more accepted that it simply isn't true. It doesn't really make sense that we require the sheer amounts of food that we're eating on a regular basis. Most omnivores and carnivores aren't eating the equivalent of 3 meals a day, and are effectively practicing some form of fasting. If we're supposed to not skip breakfast, then all our ancestors must have been pretty unhealthy, yet fossil evidence doesn't really demonstrate this.
A grazing type diet can be perfectly fine for someone at a healthy weight, but they're not really benefiting from it in any way besides the enjoyment of eating. Even so, it depends on what the person is eating in the first place. If someone eats toast with jelly for breakfast, it's highly questionable whether they're getting any long term health benefit from that at all.
There's a plethora of information about this subject, and I don't have the time to cite it all here. I encourage you to update your knowledge here. Most general practitioners aren't well educated in nutrition, nor are they versed in the latest research, so your doctor may be operating on old wisdom that hasn't panned out.
That being said, I will concede that specifically for some (not all) people with some eating disorders, restricting intake can be detrimental to recovery as it increases the chance of a binge later in the day. If you have binge eating disorder, be aware of that if you're considering intermittent fasting.
This is exactly why I don't do that well with fasting, and I don't even have an eating disorder. With anything more than 16:8, it's very easy for me to start binge eating, so the whole thing becomes counterproductive.
Every time I seriously lose weight (usually twice a year, once after winter and once after Christmas), it's eating small, high protein/low-carb meals every 3 hours or so. That puts just enough volume into my stomach to keep the hunger pangs at bay.
That has been my experience as well. I feel full a lot more quickly with IF. Even if I fall off the wagon sometimes, I can count on IF as a quick way to fix overeating.
2. Yes, it's what I do and I find it works well. If you love breakfast, skip dinner. If you say I love breakfast and I love dinner, well you just won't have the appetite for one of them because of your new ruitine, so it won't really matter. If you start eating at 12pm, you'll want to stop eating by 8pm. If you start eating at 6 am, you'll have your last meal of the day by like 3pm.
3. See above, but as soon as you start eating, the window is now open for business and you may indulge. Ideally, you'll want to compound all of this with a healthy, balanced diet with lots of water, good nights rest, exercise, and limiting stress.
It's basically applying a bunch of very simple principles, and sticking with it. The results will show, for sure. The biggest thing is getting in tune with your body and seeing what works best.
That last point is the key: it's a lifestyle change, not a diet, so you need a regimen that is acceptable enough to actually make it a daily routine.
Fasting for a day or three is worth exploring as well and is much easier to do if you're already doing the aforementioned time/carb restricted approach.
The first chapter of the book is titled, "The All-Important Protein." This struck my 2020, DNA-oriented mind as an odd starting point, yet Asimov was very clear: "all life is protein." The book is remarkably lucid, and here's one of the best portions of the book:
"Suppose the food you ate contained very little fat. That wouldn't bother your body a bit. It would take the carbohydrate you eat and turn it into fat. It happens all the time. Everyone knows what starchy foods will do for the waistline.
"If both fats and carbohydrates are low, the body is still not at a loss. It can manufacture both out of the proteins of the diet.
"Where the body does get stuck is in the case of a shortage of proteins. It cannot manufacture proteins out of fats and carbohydrates. Proteins require nitrogen, and neither fats nor carbohydrates have any. So proteins can only be obtained for the body by making certain that protein is in the food. It is impossible to live on a diet of starch, butter and sugar. You can get all the energy you need, but you can't build tissue."
Asimov places heavy emphasis on the two primary categories of what our body cannot naturally produce: essential amino acids and vitamins. Amino acids are the building blocks of proteins. The human body cannot produce nine of these amino acids, and we term these to be "essential" (Asimov said there were only eight; the necessity of histidine for adults was not yet established in 1954.) We must acquire the essential amino acids from a source outside our body. If we don't acquire these essential amino acids, our bodies will fall apart. Wikipedia says "protein deficiency has been shown to affect all of the body's organs and many of its systems" [1]. Asimov later discusses the importance of vitamins, or "atom groupings, which the body cannot make for itself and must get from the food it eats." Without vitamins, we cannot produce certain coenzymes and will fall ill and possibly die.
Essential amino acids and vitamins. I've been focusing my diet on the acquisition of those in correct quantities. My diet-optimizing function seeks to minimize sugar, maximize protein, and moderate the rest. So far, it seems to be working well; I still build muscle at the gym and fat stays off. Wonder if this is what keto basically optimizes for as well.
So many articles about bodily function I've seen online jump straight to considerations of DNA. Certainly, this approach is more accurate, though I do wonder if we the layperson are approaching health issues with too much detail. To analogize to software, it's like we're trying to debug our complex C++ program by pouring over the binary. The issues are far more likely to be with what we're putting in than what's already there.
Sources:
Oy. Why do we do this nonsense? Why can't it just be research that helps us better understand how to eat healthy?
/pet peeve
This is ultimately a product like any other. Like a SaaS product making any hard process easy, you wouldn't expect the solution to be wholly free. People would still have the option to take a different route (caloric restriction) to accomplish the same, but it's clear many people struggle with that.
X solution: Actually makes people healthy, doesn't make you rich. Gets no press because it's not making you rich.
Y solution: Kind of, sort of addresses some health issue, but at the price of terrible, horrifying side effects. Also: Makes someone rich. Gets all the promotion while no one hears anything about the cheap solution that doesn't come with horrifying side effects and a huge literal price tag.
Would you rather we don't have medication for (type II) diabetes and instead just went around telling people to eat better?
Second, because the theoretical good and the actual results don't align. We could end many STDs by only monogamously coupling for a generation but that isn't going to happen and virginity pledges haven't helped at all.
If "the right way" doesn't actually help in practice can it even be called right?
I don't think research into how to eat well really compares one-for-one to morality policies of "sex is always bad and we will allow for one and only one right way to ever get laid while still making you feel like shit for wanting it at all."