The ketogenic diet is in the spotlight again, both in the research community and in discussions among the general public.
While there is still much to study and learn regarding the use of ketogenic diets for the treatment or prevention of various diseases, the research is pretty clear on how effective they are for fat loss.
After all, the results of the recent metabolic ward study by Hall et al did show that ketogenic diets don’t seem to provide a metabolic advantage or result in a higher rate of fat loss when compared to isocaloric non-ketogenic diets with equal amounts of protein.
Funnily enough, by the way, the study was funded by the Nutrition Science Initiative (NuSI) for the exact purpose of proving that the insulin-carbohydrate theory of obesity holds true and that a ketogenic diet is superior for fat loss.
Well, Gary Taubes, if you are reading this: HA! In your face!
The study above, according to the majority of the scientific community, put the final nail in the coffin of the insulin-carbohydrate theory of obesity.
However, although this may come to you as a surprise, it’s been a little over 40 years since we first got a pretty good indication about how well a ketogenic diet works for fat loss and about how it compares to a non-ketogenic diet.
The ketogenic diet metabolic ward study of 1976
Yep, you read that right.
It was in 1976 when the first metabolic ward study which compared ketogenic to non-ketogenic diets was published in the Journal of Clinical Investigation.
At the time, little research existed on the topic and there were no other studies that directly compared the effects of a hypocaloric ketogenic diet to a hypocaloric non-ketogenic diet on body composition in a metabolic ward setting.
This was exactly what Mei-Uih Yang and Theodore VanItallie from the Department of Medicine and Institute of Human Nutrition of the Columbia University’s College of Physicians and Surgeons set out to investigate.
What the researchers did
The researchers used six obese male subjects, which they studied in a metabolic ward setting for 50 days. The subjects completed 10 days of the following three experimental schedules, each preceded by a 5-day 1200-calorie mixed diet:
- 800-calorie ketogenic diet
- 800-calorie non-ketogenic diet
- starvation diet
Note: Since this article is about comparing a ketogenic diet to a non-ketogenic one, we will simply not deal at all with the starvation schedule – this doesn’t affect the results or conclusions in any way.
With regards to the diets, they were all liquid-based diets and were served to the subjects in four isocaloric feedings at 8:00 am, 11:00 am, 1:00 pm and 6:00 pm.
The composition of the diets was as follows:
Ketogenic diet
- 800 calories
- 50 grams of protein (25%),
- 62 grams of fat (70%) and
- 10 grams of carbohydrates (5%).
Non-ketogenic diet
- 800 calories
- 50 grams of protein (25%),
- 27 grams of fat (30%) and
- 90 grams of carbohydrates (45%)
Body composition was assessed using the energy-nitrogen balance method, which, essentially, uses the measurement of nitrogen balance to estimate changes in body protein content and then uses energy balance measurements to estimate changes in body fat.
As you can see, the study’s methodology has a few extremely important strong points, including the following:
- The subjects spent the entire 50 days in a metabolic ward and had their meals prepared for them, which means that misreporting of food intake is not a concern as with most free-living studies.
- The ketogenic diet and non-ketogenic diet were isocaloric – their caloric content was the same.
- The protein intake was matched between groups – this is vital, since protein has a high thermic effect which, if not taken into consideration, will distort the results.
The results
A number of things were measured during the study, including nitrogen balance, energy balance, BMR, ketone levels and so on.
As you would expect, there were no statistically significant differences between the ketogenic diet and the non-ketogenic diet for BMR, nitrogen balance or energy balance. There was, of course, a significant difference in the daily excretion rates of ketone bodies, with higher rates observed for the ketogenic diet condition.
Weight loss and body composition
However, what we (and, presumably, you) are mainly concerned about is the weight loss and body composition results, right?
Well, here they are.
Both the ketogenic diet and the non-ketogenic diet resulted in statistically identical changes in body composition, although the ketogenic diet caused more weight loss which, according to the data, was entirely attributed to water weight loss.
To quote the authors:
“…the increment in weight loss exhibited during the ketogenic diet period was due solely to excretion of excess water. Rates of fat loss were not significantly affected by the composition of the diet.”
As you can see in the figure above, both the ketogenic diet and the non ketogenic diet caused the exact same rate of fat loss – however, the ketogenic diet just resulted in a bigger drop in water weight.
If these results sound familiar, that’s because they are identical to the results that Dr Kevin Hall and his colleagues got in their recent metabolic ward study which we mentioned at the start of this article!
Yep, we have had a metabolic ward study since 1976 which compared a ketogenic diet to a non-ketogenic diet while controlling for caloric intake and protein intake and showed absolutely no differences in fat loss.
Beating a dead horse (which insulin didn’t kill)
So, if the research has refuted the insulin-carbohydrate theory of obesity, why are we still beating that dead horse 40-something years later?
Well, it could be because some people are actually making money by having you believe that insulin is the enemy and that they can protect you from it by selling you stuff (we don’t want to point fingers here and the images below of Jason Fung, Gary Taubes and Peter Attia have nothing to do with this).
Conclusions and recommendations
So, with the results of the studies above in mind, what can we conclude?
In our opinion, it’s pretty safe to say that, at least in the short term, a ketogenic diet doesn’t provide a metabolic advantage over a non-ketogenic diet, nor does it result in increased rates of fat loss. It does, however, result in more initial weight loss because of water excretion.
The above, of course, certainly doesn’t mean that ketogenics diet are useless for weight loss. It just means that ketogenic and low carb diets work as well as other dietary approaches for weight loss, provided that they help you achieve a caloric deficit consistently over time.
This goes for any dietary intervention, by the way. Unless your fat loss diet respects your personal preferences and is sustainable in the long term, it won’t result in permanent fat loss.
And that’s pretty much the take home message.
If you want sustainable weight loss, find a diet which you don’t hate and which helps you eat fewer calories than you expend consistently over time, preferably with the majority of your calories coming from minimally-processed, micronutrient-dense foods.
And get enough protein.
And lift weights.
And share this post.
https://medium.com/@davidludwigmd/is-the-carbohydrate-insulin-model-dead-the-rumors-have-been-exaggerated-9401d1b8d9ac#.htedcvxiy
Thank you for your comment, David. We have already read Dr Ludwig’s reply to Dr Hall regarding the study.
As per our article here, the study in question was actually funded by the Nutrition Science Initiative (NuSI) for the exact purpose of proving that the carbohydrate-insulin model (CIM) of obesity holds true and that a ketogenic diet is superior for fat loss.
The study, of course, showed otherwise and the proponents of the CIM are now criticizing the study’s methodology and requesting more research to be done. Talk about hypocrisy, right?
You may also be interested in reading Dr Hall’s reply here: https://www.ncbi.nlm.nih.gov/pubmed/28074888#cm28074888_52846
great put up, very informative. I’m wondering why the
opposite specialists of this sector don’t notice this.
You should continue your writing. I am sure, you have a huge readers’ base already!
The advocates of the carbohydrate-insulin model are, probably, ignoring these facts because they have a lot invested in their position. When something makes you a lot of money, it’s hard to admit that you were wrong about it…
Thanks, we will definitely keep writing!
Please keep sharing our content so that we help as many people as possible!
Upton Sinclair’s quote: “It is difficult to get a man to understand something, when his salary depends on his not understanding it.” comes leaping to mind!
Haha very true!
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Thank you so much! Knowing that people like you find our blog helpful and informative is what fuels our passion to keep writing! Have an awesome day!
10 days is just the right amount of time to produce this misleading result. Glycogen stores have only just begun to be depleted and the switch to energy being primarily from stored fat (which holds all that water) barely started. The test needs to be repeated but over 90 days to show a clear conclusion.
Are you suggesting a 90-day metabolic ward study? Do you have any idea how much that would cost?
Here’s a 42 day intervention (not a metabolic ward one) showing that when calories and protein are matched, there are no differences in fat loss between groups: https://www.ncbi.nlm.nih.gov/pubmed/15601961
“Our results showed no significant weight loss, lipid, serum insulin, or glucose differences between the two diets. Lipids were dramatically reduced on both diets, with a trend for greater triglyceride reduction on the VLC diet.”
Also, here are the results from this (https://www.ncbi.nlm.nih.gov/pubmed/28193517) recent meta analysis (the highest form of scientific evidence)
“While low carbohydrate diets have been suggested to partially subvert these processes by increasing energy expenditure and promoting fat loss, our meta-analysis of 32 controlled feeding studies with isocaloric substitution of carbohydrate for fat found that both energy expenditure (26 kcal/d; p<0.0001) and fat loss (16g/d; p<0.0001) were greater with lower fat diets."
The post is some months old…
You are right. There are few studies that actually had a proper experimental design. Most of them did not get the protein content right: way too high or the CHO was still too high. Or too short to make any conclusions. Ward studies are expensive but if one wants to make right there is no other way around it. Sure, one can make it short and quick but than it is crap.
However, I do think that CR beats KD when it comes to life extension. But is sustainable only for few hard core enthusiasts. KD with mild CR is much easier as the CR come naturally with the KD.
Anyway…this obsession with weight loss is sickening! Even researchers don’t see past that or don’t have the balls to do so.
Best regards
Con
However, if one is diabetic, the low-carb/ ketogenic diet results in better glycaemic control. when I eat based on fats / protein my insulin requirements much less.
please comment.
Hey Sally, thanks for your comment.
Yep, a higher fat, lower carb diet seems to help manage blood glucose in diabetes (which, of course, means less insulin) and can also help with hunger control. In general, people who are less insulin sensitive may be better off using a lower carb, higher fat approach to achieving a caloric deficit.
If one has type 1 diabetes i.e. is insulin sensitive, a low-carb/ketogenic diet is fine. However, if one has type 2 diabetes i.e. is insulin resistant, there’s impaired clearance of glucose *and* triglyceride from circulation. Ref:-
https://www.ncbi.nlm.nih.gov/pubmed/7621971
Therefore for people with type 2 diabetes, a low-carb high-fat diet results in better postprandial glycaemia but worse postprandial lipaemia, which is atherogenic.
A better solution is to reverse insulin resistance. Am I allowed to have a link to a blog post of mine about the many factors that need to be addressed to reverse insulin resistance?
Hey Nigel, thanks for your comment.
Although I agree that the better solution for Type 2 diabetes is to reverse insulin resistance (by exercising and losing weight through a hypocaloric diet), I don’t see how a discussion on Type 2 diabetes fits with our article here.
O.K. That’s why I asked. There are several *other* factors that cause IR, other than excess body fat & sedentariness.
Yep, although I would argue that excess body fat and insufficient physical activity are the two main causes of insulin resistance.
My IR was caused by insufficient Vitamin D (primarily) and insufficient physical activity (secondarily). I’m not an “outdoors” person.
There was no significant change in my weight & body fat between the bad OGTT result (6.0mmol/L, 8.7mmol/L) and the good OGTT result (5.0mmol/L, 3.7mmol/L).
My serum 25(OH)D level was ~70nmol/L for the bad OGTT result and ~160nmol/L for the good OGTT result, thanks to 5,000iu/day of Vitamin D3.
Refs: https://www.ncbi.nlm.nih.gov/pubmed/19781131 and http://www.ajcn.org/cgi/content/full/85/3/649
Is there anything correcting a Vitamin D deficiency/insufficiency can’t do?! 😀
It’s pretty much predictable that same calories will result in same weight loss. However the more important thing is how you feel. Do you starve? Do you have cravings? Ketogenic diet, for me, is just a sustainable alternative of calorie deficit diets. Because all other high carb diets make you starve, while keto does not.
Yep, which fits with the concluding recommendations of the article to just use a dietary approach that helps you achieve a caloric deficit.
“The above, of course, certainly doesn’t mean that ketogenics diet are useless for weight loss. It just means that ketogenic and low carb diets work as well as other dietary approaches for weight loss, provided that they help you achieve a caloric deficit consistently over time.
If you want sustainable weight loss, find a diet which you don’t hate and which helps you eat fewer calories than you expend consistently over time, preferably with the majority of your calories coming from minimally-processed, micronutrient-dense foods.”
I completely agree! I have tried every diet and have lost wieght in every diet!
However keto was the ONLY diet that i didn’t have to suffer from hunger. Nor did i even bother counting calories!
I ate protien and fat to fullness and just made sure to stay under 50 total carbs. Literally effortless compared to counting and weighin every morsel that goes into mouth!
Not to mention the water loses brought down the inflammation in my
Body!
And i got crasy energy when i became fat adapted!
All other diets leave you tired! Keto boosts your energy by the second /third week!
You seem to be against keto but say it is better for people with type 2 diabetes. Do you know how many people are diabetic or pre-diabetic now? We are talking huge numbers.
Do you really think that the 30% obese population of America are all over eaters and under exercisers? Yeah right. That’s 100 million gluttonous sloths in America alone that just can’t control themselves.
If you actually understood what Taubes and Fung are saying, insulin resistance builds up over decades in a vicious cycle that people don’t know how to get out of.
The Us govt recommended a high carb diet in the late 70’s. When did obesity explode? We must have a lot more over eaters these days I guess.
You say they make heaps of money out of what they do. I’m sure you make money out of this too. If people knew they could lose weight by controlling insulin levels without exercise I’m pretty sure you might be out of a job too.
Obesity is a hormonal imbalance in the body and if you control the hormones responsible you control obesity.
You know better than anyone a 50 day test is worthless….
Thank you for your comment, Tony!
I am, actually, not at all against keto. I think that ketogenic/low carb diets can have their place, as can high carb, low fat diets, protein sparing modified fasts, “paleo”, time restricted feeding, and other dietary approaches, depending on the context.
With regards to the cause of obesity, I highly encourage you to read this scientific review: https://www.annualreviews.org/doi/full/10.1146/annurev.publhealth.29.020907.090954?url_ver=Z39.88-2003&rfr_id=ori%3Arid%3Acrossref.org&rfr_dat=cr_pub%3Dpubmed&
Here’s a relevant quote you may find informative: “The purpose of this exploratory study is to assess the relative impact of caloric intake and energy expenditure on the rising obesity epidemic in developing countries and to explore the drivers of the energy imbalance. The available data on energy expenditure, albeit limited, suggest that physical activity has declined but that the magnitude of the change is probably too small to explain most of the rise in adult obesity. With the exception of Australia and Finland, our analyses suggest that increased caloric intake is the driving force behind the growing obesity epidemic. However, we do not diminish the importance of energy expenditure to weight management and overall health.”
I kind of agree with Tony, you probably just misunderstood Dr. Fung. When you see obese person with (or without) diabetes type 2 and look at his or her diet and lifestyle, it’s fairly easy to figure out what is the culprit. “Low fat” (read high sugar), constant snacking between main meals, foods overloaded with carbs and calories, not enough physical activities… Of course any dietary restrictions and exercise work.
Thank you for your comment, Stan.
Please allow me to disagree on your point about obese people eating a low fat diet.
According to the available evidence, the intake of both fat and carbohydrates has increased over the last few decades through the increase in added sugars, saturated and trans fats, and, generally, highly-refined foods. This has, of course, led to an increase in overall energy intake which, combined with lower activity levels, is causing the obesity epidemic.
Here’s a cool graph: https://wol-prod-cdn.literatumonline.com/cms/attachment/9db9ff21-99ba-4fab-b820-fde1f3ec879a/oby22073-fig-0001-m.jpg
Full text of the relevant study here: https://onlinelibrary.wiley.com/doi/full/10.1002/oby.22073
That was 2008. It was less than certain about the cause as well. I think the rise in caloric intake is due to mostly sugar and refined carbs because people eat them and then feel hungry 2 hours later.
What do you think about insulin resistance causing people to put on weight?
I am not here to cause trouble, I just like to get a rounded view of issues when I explore them.
the USDA figures show people are eating around 25% more calories in the USA compared to 50 years go. This increase is made up mainly of additional fat and refined carbohydrates. So the question of why people are fatter is not terribly difficult. It is definitely worth noting however that fat consumption has gone up and not down as many claim.
Plus its tiresome when people mention that low fat/calorie reduction has been recommended for many decades yet people are fatter than ever, so that MUST mean that the advice was wrong. As if all those morbidly obese people were strictly following health guidelines, not overeating or binging and just magically getting fat anyway. For some reason certain people never even consider people are getting fatter as they are simply not following the advice, which is supported by the evidence of increased calorie consumption…..
I don’t think you are getting my point though. The government said carbs are better than fat but carbs (flour and sugar) are almost an addictive substance. Once people get hooked on them, they need more and more to feel satiated. That is where the extra pounds are coming from.
I’m not sure if the government said that carbs are better than fats… On the contrary, the latest dietary recommendations suggest that moderate amounts of all macronutrients are a good idea, and that we should limit intake of added sugars.
In general, a diet that is based mostly on veggies, fruits, lean meats, fish, nuts, olives, seeds, avocados, legumes, and whole grains is a great start for most people. Of course, personal preference is important, and people should make adjustments to make sure they can adhere to their diet.
In my humble opinion, even though you are 100% correct you missed the entire point of ketogenic diet (as well as “starvation”, which is incorrect expression because there is a huge difference between starvation and fasting). True, any caloric restriction works – as long as individuals adhere to the plan, especially when we are talking about long term. The issue is not caloric restriction; the issue is really adherence.
For the past X decades we all heard “Eat less, exercise more”. Which is a great idea, it may work for some, however in reality it doesn’t work for most. “Eat less” is the logic behind most diets, and we know that 90-95% of all diets fail. Hence the obesity epidemic, people are simply overeating while keeping physical activities at minimum. When person “eats less”, he or she is simply still hungry. When he adds exercise, he is then even more hungry. How long can that last…?
Ketogenic diet and fasting are not miracles. They’ve been around for thousands of years, and at the end of the day they are also simple caloric restrictions. The difference is that a person doesn’t just restrict caloric intake: He feels less hungry because of increased ketons (fat), or he stops eating at all during fast.
Let me repeat that one more time: Zero calories during fasting, whether it is 16 hours, 3 days, 1 week, or even longer…
Based on my experience, not eating at all is way better approach than “eating less”. For instance, this is my second day of fast; no food at all, only water, and I am simply not as hungry in comparison to restricted diet/limited calories. I feel like this is a miracle: I am losing weight, I am losing fat, and I am not really that hungry. I can do moderate physical activities with no problem at all, including multiple dead lifts with 230 pounds, and I feel actually quite well. Do I starve? Heck no, I can start eating again anytime I want. Do I feel hungry? Little bit throughout the day, but it is not really that bad. This will go away in another 2-3 days. So, is it a real miracle? Probably not, on a paper it is simple caloric restriction. But it does feel like one, in comparison to “eating less”…
Hey Stan,
I don’t think we disagree, to be honest.
This article specifically discusses the claim that ketogenic diets have a metabolic advantage (they don’t).
The issue of dietary adherence to a ketogenic vs. non-ketogenic diet is beyond the scope of this article, as is the issue of adherence when utilizing an intermittent fasting approach.
Indeed, research suggests that both the aforementioned approaches can improve dietary adherence in many (but not all) people.
In quick summary, there is currently obesity epidemics, as we all know. What is the cause? It is of course excess of calories (some combination of carbohydrates + proteins + fats), and sedentary lifestyle. If one consumes 2500 calories per day but only burns 2000, he will eventually get fat. Fat is simply stored calories, excess food for later use.
Our bodies react differently to high carbohydrates vs high fat diet intake: High carbohydrates intake increases insulin, and eventually, down the road, it may lead to insulin resistance and diabetes type 2. Proteins also rise insulin levels, but not so fat.
Common sense logic tells us to decrease total amount of caloric intake, and add some excercise to burn more calories, to burn fat. In simple words: Eat less and excercise more. Also, many times current trend is eat several times per day, perhaps to avoid being hungry.
Although great logic, does it really work in real life? Well, obesity rates are increasing. People using this approach lose weight for some time, but then they gain it back. In reality, over some 95% diets (or 99% ?) fail. Person cuts down calories, say to 1500 per day. He add exercise to burn even more calories. He eat six times a day, though lower portions, to avoid hunger. But what happens? Metabolism slows as body is trying to adjust to new daily caloric intake. Person may lose some weight but he also gets tired, exhausted, stressed out. He is still hungry anyway, now pretty much all the time. He will eventually start eating more, and now, after couple months later, all his weight is back. Sometimes even more. All hard work is lost no matter how hard he tried; maybe he’ll try two more times, before he forever gives up…
All this mainly because insulin continues to be elevated throughout the day (as he continues to consume carbohydrates + proteins several times per day). Elevated insulin blocks lipolysis – maybe there is some fat burning, but not really that much because high insulin doesn’t allow break down of stored fat. If we eat six times a day, insulin is elevated six times. Body can’t really burn fat, there is not enough time for fat loss. Body is starving on 1500 calories, because of elevated insulin it can’t use stored fat as fuel…
So now comes elegant solutions: Fasting. We don’t consume decreased amount of calories six times a day, we cut the entire food supply, say for example we don’t eat 18 hours per day. Zero calories in X hours, or better: X days. What happens in the body? Insulin level drops and it stays low for X hours. Low insulin level during 18 hours fasting allows lipolysis: stored fat is broken down and used as fuel. Body is now using stored fat as fuel. Insulin resistance improves, or totally disappears. Diabetes mellitus T2 improves, or hopefully disappears. Growth hormone rises, norepinephrine rises. In males, testosterone level rises. More fat is burned.
Similar logic is applied in ketogenic (high fat, low or no carb) diet. High fat doesn’t increase insulin, insulin remains low. Stored fat can be burned, used as fuel…
It is of course more complicated, but it makes a lot of sense. It simply explains why “Eat less and exercise more” doesn’t really work in real life, for most people. It explains why more than 95% diets fail. Note that there is also a huge difference between e.g. healthy guy in his 40’s who is 180 pounds and is trying to shed couple extra pounds off for the summer, vs guy who is 270 pounds, with diabetes, high blood pressure and high cholesterol, who cannot move because both of his knees constantly hurt.
Fasting is of course not a miracle, it is still hard work that requires discipline and will. Nobody can undo decades of over-feeding and crappy diet in one month. But it is reasonable solution to current problem, perhaps only second to: DO NOT GET FAT AT FIRST PLACE
Good Talk
Dr Eric Westman himself has said that Low carbohydrate and ketogenic diet work because of reduction calories.
Also, one of the main claims as of the efficacy of ketogenic diet and low carb I is that they increase satiety (in some people but maybe not all) which increases adherence to the diet which increases ability to eat less… Which leads to weight loss. Again, find the diet that you can stick to and stick with it
Yep! 🙂