Tuesday, April 29, 2014

Fat vs. Carbohydrate Overeating: Which Causes More Fat Gain?

Two human studies, published in 1995 and 2000, tested the effect of carbohydrate vs. fat overfeeding on body fat gain in humans.  What did they find, and why is it important?

We know that daily calorie intake has increased the US, in parallel with the dramatic increase in body fatness.  These excess calories appear to have come from fat, carbohydrate, and protein all at the same time (although carbohydrate increased the most).  Since the increase in calories, carbohydrate, fat, and protein all happened at the same time, how do we know that the obesity epidemic was due to increased calorie intake and not just increased carbohydrate or fat intake?  If our calorie intake had increased solely by the addition of carbohydrate or fat, would we be in the midst of an obesity epidemic?

The best way to answer this question is to examine the controlled studies that have compared carbohydrate and fat overfeeding in humans.

Horton et al.

The first study to address this question was published in 1995 by Dr. James Hill's group (1).  The title of the paper is "Fat and Carbohydrate Overfeeding in Humans: Different Effects on Energy Storage".  Sounds promising for the calorie skeptics.  Sixteen men (9 lean*, 7 obese) were overfed by 50 percent of calorie needs for 14 days, by adding excess fat or carbohydrate to the diet.  After a four-week break, each person was overfed the macronutrient they had not received the first time (randomized crossover design).  Subjects were provided with all food, prepared in a research kitchen, although they were allowed to consume some of it at home.

After 14 days, the researchers measured changes in body weight, fat mass, and lean mass.  Here's what they found:
There were no significant differences between diets and/or groups in body weight or body composition changes.  
Carbohydrate and fat overfeeding caused nearly identical increases in body weight, fat mass, and lean mass, and this was true both in the lean and obese groups.  Here's a graph of body weight changes:

And here's a graph of changes in fat mass:

Note that obese subjects seemed to gain more fat than lean subjects.  This is presumably because they were overfed by a greater absolute number of calories**.

If changes in body fatness were essentially identical during fat and carbohydrate overfeeding, why did the investigators choose to state in the title that "energy storage" differed between macronutrients?  The reason is that carbohydrate overfeeding caused an increase in carbohydrate burning and total energy expenditure, while fat overfeeding had no significant effect on fat burning or total energy expenditure.  In other words, the body "burned off" some of the extra carbohydrate, but it didn't burn off any of the extra fat.  A higher proportion of the fat calories was stored as body fat.

Yet in the end, the differences were small-- the body stored nearly all of the excess calories in both cases, and any apparent differences in energy expenditure were not reflected in fat mass***.  Calorie-for-calorie, body fat accumulation was approximately the same during fat and carbohydrate overfeeding.

Lammert et al.

The second study was published in 2000 by the research group of Dr. Bjorn Quistorff (2).  Ten pairs of lean young men were overfed by 5 megajoules (1,195 kcal) per day for 21 days, given as either a carbohydrate-rich or a fat-rich diet****.  Subjects lived and ate in a research setting the entire time.  The study was extremely well controlled.

Body composition was determined weekly by underwater weighing.  Increases in body weight were similar between groups, and increases in fat mass were almost identical:

Interestingly, the carbohydrate-overfed group actually gained more lean mass than the fat-overfed group.  It's unclear to me whether that reflects actual tissue gain, or simply increased glycogen storage.  Another interesting thing to note is that fat gain varied tremendously between individuals.  Due to genetics, physical fitness, and/or other factors, some people simply store more body fat when they eat excess calories, while others burn most of it off.  This has been confirmed repeatedly.

In any case, this study confirms that fat gain is approximately the same whether people overeat fat or carbohydrate.

Bonus Study: Hirsch et al.

We know that carbohydrate and fat cause approximately equal fat gain per unit calorie during overfeeding, but what happens when people aren't overeating?  Does the proportion of calories supplied as fat or carbohydrate affect body fatness in that scenario?

The research group of Drs. Rudy Leibel and Jules Hirsch kept a series of subjects under metabolic ward conditions, strictly controlling the diet and dramatically varying the proportion of carbohydrate to fat, while keeping calories constant, for several months at a time (3, 4).  Here's a summary of their findings:
We showed that the carbohydrate-to fat ratio could vary widely with little or no alteration in the energy requirement for weight maintenance.  The results of a 13-week study in which an individual was fed a formula diet extremely rich in carbohydrate and low in fat for a period of 38 d and, thereafter, for a longer time, a diet rich in fat and low in carbohydrate are shown in Figure 1 [see below-- SG].  Weight varied little throughout the study and average energy intake was the same throughout...  The reason for emphasizing these findings is that under the strict conditions imposed by hospitalization and feedings of a formula diet, energy needs are the same over long periods of time even though carbohydrate-to-fat ratios vary.  Similar data were accumulated in 15 subjects.
Here, you can see the weight trajectory of the woman described above:

Over a fairly long period of time, her weight stayed within a 1 kg range, despite huge differences in diet composition.  The same thing was observed in a number of other subjects.

In other words, under non-overfeeding conditions, the carbohydrate and fat content of the diet have no measurable impact on body weight when calories are controlled.


There are always caveats when interpreting scientific evidence.  Here are a few for today:
  • The studies we discussed were small.
  • They may not have been long enough for differences to emerge.
  • The overfeeding studies didn't include women.
  • The overfeeding studies reported significant individual variability.  In other words, some individuals may gain body fat more readily when they overeat carbohydrate, while others may be more sensitive to fat.  Or not.  We can't really say based on these studies, but it remains possible. 
Scientific evidence is never perfect, but at some point we have to decide which hypothesis is best supported.  In this case, the clear winner is the hypothesis that total calorie intake determines body fatness, but not the proportion of dietary fat or carbohydrate.  

Based on the available evidence, the US obesity epidemic probably resulted from an increase in total calorie intake, not from changes in fat or carbohydrate intake that were acting independently of total calories.  We would likely be faced with the exact same obesity epidemic if our increased calorie intake came exclusively from fat, or exclusively from carbohydrate.

That being said, macronutrients (fat, carb, protein) are not irrelevant to body fatness!  They can impact fat storage by affecting how many calories we eat.  Added fats tend to increase calorie intake, while high-protein diets tend to decrease calorie intake.  Of course, refined and processed versions of fat and carbohydrate tend to favor higher calorie intake as well, due in part to higher calorie density and palatability.

Somewhat paradoxically, once a person is overweight or obese, increasing the proportion of protein and fat at the expense of carbohydrate can help control appetite and reduce body fatness.  During moderate carbohydrate restriction, this effect seems to depend mostly on increased protein intake, but during more extreme carbohydrate restriction, there may be a role for ketones.  I think there are still mysteries here that deserve further scientific exploration.  

* Average body fat percentage of lean group = 21.4%, which is not particularly lean for a man.  BMI = 21.3, which is low, so these people probably had a fairly undesirable body composition on average.  The investigators specifically excluded "highly trained individuals".

** Subjects received a 50% calorie excess.  Since obese people have a higher baseline calorie expenditure than lean people (25% higher in this study), the excess calories during overfeeding would be greater in an absolute sense.

*** The investigators do state that the body composition changes they measured were near the detection limit, given the short duration of overfeeding.  The subtext is that the fat overfeeding group may have ended up gaining a bit more fat if the study had lasted longer.  Personally, I'm skeptical of this possibility, due to the nearly identical body composition changes they reported and the results of Lammert et al.

*** Carb-rich: 11%, 78%, 11% of calories as fat, carb, protein.  Fat-rich: 58%, 31%, 11% of calories as fat, carb, protein.  In the carb group, a lot of the calories came from sugar (sucrose).


Jenny said...

The missing piece here is the effect of those extra carbs on blood sugar. In free-living people with damaged blood sugar metabolisms, extra carbs will increase blood sugar spikes and hunger, leading to more food being eaten.

Blood sugar metabolism is damaged by exposure to SSRIs, statins, and a long list of estrogenic environmental pollutants, arsenic, herbicides and who knows what else.

So while yes, eating more causes the increase in obesity, a major cause of that eating more is the damage to the blood sugar regulating system.

--Jenny Ruhl

Toma Que Tomás ('Mash) said...

Many thanks for your continued work Stephan. Always appreciated!

Asclepius said...

Interesting post. Demonzing a macro nutrient is a busred flush. But lets not forget that CICO still contains no causal information. Furthermore, grazing & inactivity are vital to blur signal & noise; information otherwise needed by your body to control appetite, motivation & activity.

RPH said...

Well said. Thanks. Unfortunately the norm is not a healthy state here.

Greggatshack said...

Another missing element is that satiety is not measured. Is a carb rich diet likely to lead to overeating because the subject feels hungry more often, while a fat rich diet may lead to better eating habits because the subject doesn't feel hungry.

Katya Anderson said...

I find it interesting that Western populations gain more weight for the same number of excess calories than traditional populations eating traditional foods (see Guyenet's previous post on the Massas people.) Is the difference due to diet quality, leptin sensitivity, or something else?

Fred Perez said...

Im a fan of cylical low carb diets not a big high fat guy all the time, but even I have to say
30% carbs in the high fat group in an overeating scenario is a huge confound.

George Henderson said...

"the carbohydrate-overfed group actually gained more lean mass than the fat-overfed group. It's unclear to me whether that reflects actual tissue gain, or simply increased glycogen storage."

It could be water weight. Why would water be important when weight is lost, but not when it's gained?

These people ate more because they were motivated to do so. We don't know which group found eating more to be harder work, which choice would have been more conducive to overeating IRL.

Dr. Art Ayers said...

Do you think that all of the individual variability would disappear if all of the test groups received fecal transplants from the same donor?

Gina Fourie said...

I wonder if you could comment Stephan about the extra fat mass the obese subjects gained in Horton et al (1995)? Is it possible that the 50% excess calories calculated for the obese subjects over predicted calorie requirements. In my experience estimated energy requirement formulas over predict in obese subjects and the degree of over predicting is amplified by the degree of obesity? Did Horton et al use predictive equations or measure metabolism directly?

Avishek Saha said...

Jenny - extra carbs aren't affecting the blood sugar as you think. The "blood sugar regulating system," or insulin as you're referring to, becomes damaged by excess fat mass, not carbs or fats alone. Excess fat mass releases FFAs into the bloodstream where insulin signaling is hampered. A high fat or a high carb diet can cause insulin resistance, if weight gain especially in the visceral region occurs.

Good post Stephan, we should stop blaming macronutrients.

Justin said...

Seems like TEF would come into play in cases of overeating carbs (moreso, relative to overating fats) in that it takes work to convert carbohydrate molecules into triglycerides. Sure it might be only a little work, but it's work, right? Meanwhile, fat can be stored more easily via DNL (right?). I know I'm painting with broad strokes, but I find this interesting. This could also explain a rise in metabolic rate if you overeat carbs.

Relevant: overeating protein? Obviously excess protein gets metabolized, but how much of it gets stored? The pathway to go from protein molecules to carbohydrate molecules to fat molecules would be very wasteful.

And perhaps this explains my anecdotal experience with drinking tequila (thus putting alcohol at the front of the line for metabolization) and eating a good bit of protein (chicken, dairy, whey) and some carbohydrates (beans, berries) resulting in elevated heartrate (happened to me the other night and made for awful sleep -- about a 20 bpm increase in my sleeping heartrate).

Jael Camacho said...

I think the issue will be trying to see minor details instead of focusing on the bigger picture. We eat more and tend to do less physical activity. How any macro nutrient affects a paritcular person depends solely in the physiology and psychology of that person. From energy storage, to macro oxidation, to hormonal balances, it all depends on the person. Needless to say, one size does not fit all.

Stephan Guyenet said...

Hi George,

Glycogen weight is mostly water weight because glycogen is so hydrated, so we're basically hypothesizing the same thing.

Hi Dr. Ayers,

I doubt all of the variability would disappear-- but it might be reduced, who knows.

Hi Gina,

They directly measured individual calorie requirements in the run-in period, and what they reported is consistent with other reports of energy requirements of obese vs. lean people (usually ~20% higher in obese). So I don't think they overestimated calorie requirements.

Hi Justin,

TEF could play a role, although diet-based variability in TEF has a limited impact on total energy expenditure, particularly in the case of fat and carbohydrate. You might expect biochemical "inefficiency" to contribute to energy expenditure at the macronutrient extremes (less than 10% fat or carb), where the body is having to synthesize a lot of fat or carbohydrate. Between the extremes, the body probably doesn't do enough DNL or gluconeogenesis to contribute significantly to total energy expenditure.

Your tequila story might have another explanation-- the Red Bull you mixed it with. JK.

Shashi Guruprasad said...

The missing piece here and in many areas of health is almost always gut micro biome and how it affects hormones, and host metabolism.


The variety of plant and animal foods, resistant starch, antibiotic and NSAID use, glyphosate and other xenobiotics in food supply, antibiotic resistant strains of pathogenic bacteria in our food supply, and probably many other externalities are responsible for variation in our gut micro biome than we know about.

Robert said...

Hi Dr. G,

These researchers hypothesize that lack of protein in processed junk foods is driving overconsumption of fat and carbs, and therefore calories, which is driving obesity.


Thanks, -Robert

Robert said...

Which means that Atkins and the potato diet may work simply b/c they both have lots of protein and are not hyper-palatable. Which meshes with the protein-focus of you and Dan Pardi's diet plan.

Ned Kock said...

Stephan: in the Lammert et al. study it seems, based on your graph, that weight gain was greater and fat gain was smaller in the fat-overfeeding group. Therefore, one could conclude that it was the fat-overfeeding group that actually gained more lean mass.

Unknown said...

Fat-rich: 58%, 31%, 11% of calories as fat, carb, protein

With so many carbs and so little protein, it doesn't really mirror any seemingly decent lchf diets?

Real studies are definitely required, but I feel like there are way too many people trying to disprove either side with tunnel vision.

Alan Smithee said...

This is very interesting, Stephan, because I was always under the impression that de novo lipogenesis (the conversion of carbohydrates into fat) was minimal in humans and that the body burns off ~85 of excess carbohydrate calories through thermogenesis. Is that untrue? Or is dietary fat about as thermogenic as carbohydrate?

Angela said...

Have you considered the impact of the variability that exists in the kcal/g using the Atwater system? (http://www.foodnavigator-usa.com/R-D/Should-we-revise-how-calories-are-measured) I think that part of the reason that people lose weight when they switch to Paleo or other higher fat patterns is due to their increased intake of complex plant foods that likely have fewer kcal than estimated by Atwater factors. I also believe this is interconnected with the microbiome and its efficiency at completely metabolizing foods, but I'm not sure to what extent these two variables might affect weight and even each other as complex plant foods benefit the microbiome in normal circumstances while refined carbohydrate likely harms. I do believe that people who are overweight tend to have altered microbiome, but then again, there's the chicken or the egg question. Fascinating topic!

JM said...

So if I eat 3600 calories per day, it doesn't matter if I go with 700g of carbs or 280g of carbs, weight gain is the same.

Unless I carb-backload most of the 280g of carbs after strength training...?

I'd probably go with 17% protein, and white rice instead of sugar, grass-fed butter instead of vegetable oil.

The individual confounding factors are limited to gut flora, circadian rhythm, fitness plan, nutrient deficiencies, meal timing, stress-reduction habits, sleep, social life, etc...

But once you go over 100g of carbs, using 50% overfeeding, it looks like a calorie is a calorie.

raphi said...

Hi Stephan,

"We would likely be faced with the exact same obesity epidemic if our increased calorie intake came exclusively from fat, or exclusively from carbohydrate.

That being said, macronutrients (fat, carb, protein) are not irrelevant to body fatness! They can impact fat storage by affecting how many calories we eat"

Herein is the difference between stating a contradiction and simply contradicting ones self. In this instance it is the latter IMHO.

יובל חרלפ said...

Stephan, is there a research similar to this comparing protein vs carbs ?

Steve Bates said...

Is that third graph correct? You say:

"Interestingly, the carbohydrate-overfed group actually gained more lean mass than the fat-overfed group. It's unclear to me whether that reflects actual tissue gain, or simply increased glycogen storage."

But the graph shows greater total weight gain in the high-fat group. How could the high-fat group still weigh more if body fat gain was comparable in both groups and the high-carb group gained more lean mass?

Stephan Guyenet said...

Hi Shashi,

There's not enough evidence in humans to attribute weight phenotypes to the microbiome. Seems like there's a tendency to credit the microbiome when things happen that we don't currently have an explanation for.

Hi Robert,

Could be a factor, I suppose. We might eat less if all of our processed foods were high in protein.

Hi Ned,

I noticed that discrepancy as well. I'm not sure how to explain it, but I can tell you that underwater weighing indicated higher lean mass in the high-carb group. I tend to trust the underwater weighing, but it does create a discrepancy.

Hi Unknown,

This post was not an attempt to "disprove" LCHF diets. It was specifically written to address the question of whether overeating by adding carb or fat to a typical diet causes different gain of body fat. This is relevant to the question of what caused the US obesity epidemic: was it extra calories, or was it carbs or fat having some sort of calorie-independent effect? There are people claiming it was carbs independent of calories, and that if we ate the same number of extra calories from fat, we wouldn't have an obesity epidemic. They appear to be wrong.

Hi Alan,

What you said about DNL is correct, but what you said about the body burning off excess carbohydrate is not. When you eat carbohydrate in excess of your body's energy needs, it spares fat burning and dietary fat is shunted into adipose tissue. You end up gaining the same amount of body fat as if you had overeaten fat. This may break down a bit on extreme low-fat diets (less than 10% fat) but it holds true over almost all macronutrient distributions.

Hi Angela,

I agree with your point. The best-controlled diet studies focused on foods that are well absorbed. For example, Rudy Leibel's studies used liquid food that is absorbed almost completely. That way the study is extremely well controlled because there are few differences in absorption between the different diets. But in real life, there will be differences. That's why (when I'm feeling precise) I say that the amount of absorbed energy in food is what determines body fatness. Any calories that end up in the toilet obviously don't impact energy balance.

Hi raphi,

I don't see the contradiction.

Hi יובל חרלפ,

Not that I know of.

Hi Steve,

See my response to Ned. I don't have a definitive explanation.

Dr Bob said...

Carbohydrate restricted diets result in spontaneous consumption of fewer calories (average reduction in adults 500-600 calories per day)this is well documented in RCTs (e.g.ATOZ study). As a physician I am more interested in helping people lose weight than theory of weight gain. These are different topics. Once overweight or obese what do we advise? Answer, carb restriction, this reverses metabollic syndrome and can cure diabetes II if done early. (Diabetes Care, Vol 36, April 2013, P1047-1055)carb restriction beats all other approaches repeatedly in the RCTs.

WilliamS said...

"We would likely be faced with the exact same obesity epidemic if our increased calorie intake came exclusively from fat, or exclusively from carbohydrate."

I don't see how the cited studies speak reliably to the causes of the obesity epidemic. I believe they all strictly controlled how many calories the subjects ate. Such a study design obviously has little ecological validity, since in the real world people choose how much they eat. Hence, the external validity is, to me, highly questionable.

It's possible that removing the subjects' freedom to choose how much to eat doesn't matter, but these studies can't show that, and to me it's not plausible. In a way, fixing the calorie content of the diet actually rigs the game, because unless the subjects dramatically adjust their activity levels or BMR (calories out) within the relatively short study timeframe, their mass will be mostly determined by calories in no matter what macronutrients they eat.

The real question is what happens when people dramatically increase their consumption of, say, refined carbs or sugar when they can control how much they eat, which is what happened in the real world. That kind of study design should have a lot more ecological validity, and I hope NuSi's ongoing work will finally get some answers.

Angela said...

What do you make of the results of this study? http://consumer.healthday.com/cognitive-health-information-26/lou-gehrig-s-disease-als-news-1/high-calorie-high-carb-diet-might-prolong-life-of-als-patients-685308.html

"The high-carb, high-calorie diet consisted of a commercial tube-feeding formula called Jevity 1.5, which contains 150 percent of the calories needed to maintain weight, Wills said. The high-fat diet consisted of a formula called Oxepa. Those on the weight-maintenance diet were given Jevity 1.0.
The researchers found that patients on the high-carbohydrate formula gained a modest amount of weight, patients on the high-fat diet lost weight and the others maintained their weight."

It seems to be looking at your topic in a well-controlled manner, albeit in a very select population. I don't have the actual publication, but it does seem to favor the carbohydrate-induced weight gain theory. I am interested in this topic especially because I am often working with underweight elderly people trying to promote weight gain. Thank you for exploring it!

Stephan Guyenet said...

Hi WilliamS,

Again, this post was designed to address a narrow question: can our increase in weight be attributed to the increase in calories that we know occurred, or is it due to some calorie-independent effect of the increase in carbohydrate or fat that also occurred? The former hypothesis is clearly supported by the available data.

You said "The real question is what happens when people dramatically increase their consumption of, say, refined carbs or sugar when they can control how much they eat, which is what happened in the real world". I agree, except you left out the additional question of what happens when people increase intake of added/refined fats.

One difficulty I have with NuSI and Taubes is that they often act as if we don't know anything about these questions and therefore we need new research, when in fact many studies have already been performed that are relevant. The studies are often ignored or criticized if they don't support pre-established beliefs.

In this case, I can tell you that a number of studies have already been done that are relevant to your question. In general, both refined carbohydrate foods and added fats tend to promote higher calorie intake as part of free-choice (not calorie controlled) diets, but the combination of both is the most potent. This is basically the same thing you see in rats, where diets high in fat and sugar in a large variety of tasty forms are the most fattening.

Steve Bates said...

Regarding the Lammert et al. study, one explanation I came up with is that the high-fat group had more undigested food in their intestines. Lammert et al. are vague about what the groups actually ate, but I find it likely the high-carb group would have been eating more fiber.

MAGGIE said...

So given the outcomes of these studies, if one is for example underweight and want to put weight on without resorting to getting cabs from sugars or processed foods what is the way forward .

Jim Oliver said...

This shows once again that we eat more because we can more easily afford food. So all these campaigns on what to eat rather than on how much to eat are not so worthwhile.

BUT making food more expensive or making food less good tasting/desirable is IMO a crazy solution. Not only that it is quixotic.

karl said...

This seems like a cherry picked study ( with a low 'n') designed to support the status quo theory. People that want to lose weight don't overeat calories on purpose. The modulation of appetite by low carb diets is well documented - and appetite matters.

Weight gain/loss is an effect of callories-in/callories-out - but to ignore the causes of what drives that balance is not helpful.

We know that carbohydrates cause trygly to spike and that trygly block the effect of leptin on the brain.

We also know that humans have only been consuming grass plants for the majority of their calories for a short time evolutionarily. As is also the case for lactose - the ability for humans to tolerate these carbohydrates is still something that is evolving and has health consequences.

Just consider the changes in the grains in the last 60 years - they have much increased PUFA and more carbs - less protein. ( the PUFAs are selected for frost resistance (it lowers the freezing temp due to the kinks in the carbon chains - also messes with insulin sensitivity)).

Over eating anything is bad - over eating carbs causes elevated BG which can glycate lipids which in turn form oxLDL - which are in turn misidentified by macrophages in artery walls as bacteria to engulf. That OBs are only doctors that measure post prandial BG - ends up deferring the detection of carbohydrate intolerance until permanent damage has occurred - thus IMO mainstream medicine is AWOL.

Hard to think of a more potent preventative health measure than keep Postprandial BG below 110. And that means risk of carbohydrate consumption is very important to a large fraction of the public.

Stephan Guyenet said...

Hi Karl,

See my responses above re: the purpose of the post. I'm going to be writing about the impact of dietary patterns on appetite and calorie intake in a future post.

The triglyceride hypothesis of leptin resistance is interesting but not well established. It's hard to reconcile with certain observations, e.g. high triglycerides in the Kitavans. I'd like to see a lot more work on it before feeling confident about it.

Glenn Lockwood said...

I haven't read all the comments so it may have been touched. I believe dietary fiber is a 4th macronutrient. It is a constituent in carbohydrate-containing foods but it has been discounted as a source of energy and specific types of fatty acids. I don't have the studies to cite, but a substantial amount of dietary fiber is converted to short-chain fatty acids via fermentation in the gut. Perhaps this needs more scrutiny.

Fat Bastardo said...

Fat fattens best! Fat has a whopping 9 cals per gram whereas carbs have a measly 4 cals per gram.

Cells do best on glucose not ketones and brain cells can only use glucose.

Some people think that gluttony is the moral failing that causes obesity. Some people actually think that people have a choice as to what they eat..

Some people see obesity as the result of gluttony and they see gluttony as a moral failing.

Pride is one of the 7 deadly sins. Fat people are often pride full. What people call shame is a much needed dose of humility.

Thin Shaming vs Fat Shaming Click Here to see what is worse

Many people accused of fat shaming are worried about the fat person's health.

Click HERE to read why people think The Bible Belt is the FATTEST and most SINFUL

Gluttony is one of the 7 deadly sins.

Philippians 3:19 Their end is destruction, their god is their belly, and they glory in their shame, with minds set on earthly things.

Proverbs 23:20-21 Be not among drunkards or among gluttonous eaters of meat, for the drunkard and the glutton will come to poverty, and slumber will clothe them with rags.

Proverbs 23:2 And put a knife to your throat if you are given to appetite

victor ward said...

In the world of low carb hi fat an important variable in our understanding weight control is fat quality. Do these studies you give us account for the type of fat?

Scott Mercer said...

I would like to see a long term study in a highly controlled clinical setting which limited the types of foods eaten but had no restrictions on calories. In other words, subjects could request as much food as they wanted, whenever they wanted, but each portion would have the proportions (Carbs protein and fats) strictly limited, and subjects could only get more food if they cleaned their plates, so the proportions would be highly controlled.

One period of time would include the typical high carb low fat diet (70 carb, 15 protein, 15 fat) and the other a low carb high protein (ketogenic) ratio (60 fat, 35 protein, 5 carb).

It is my suspicion that low carb/high protein works for obese people as it allows them to comsume fewer calories while remaining sated. This allows them to reduce their weight from an obese range to an overweight range, but never to get to a lean status.

This has been my experience with low carb eating anyway. I lost 110 pounds, and have kept them off over two years, but never have been able to lose those final 40 pounds so I could get to a lean body mass. My BMI went from something like 50% body fat down to about 26 or 27 with 23% body fat, but I would like to get it down to 20 or 18%.

I look forward to your future posts.

Stephan Guyenet said...

Hi Scott,

It's unlikely that study will ever be conducted, for practical reasons. It's extremely expensive to conduct long inpatient studies (millions of taxpayer $) and difficult to find volunteers who want to be locked up in a metabolic ward for months.

That said, there are non-inpatient studies that are somewhat relevant to your question. Basically, when you put an obese person on a low-carb diet, he tends to eat less and lose fat. There's a lot of variability in the response, with some people losing a lot of fat and others losing little or none.

In the Atkins-style studies, people lose weight the fastest during the ketogenic 'induction phase', then they usually regain most of it over the next year or two as they adopt a more moderate LC diet. It's not clear how much of the regain is due to the diet becoming less effective over time vs. declining adherence over time. The long-term (1-2 yr) results of those diets are pretty modest for the 'average person', although some people are able to maintain impressive weight losses. It clearly worked well for you and that is awesome.

Anonymous said...

For folks that say: let's not forget that eating carbs just make you want to eat more. Get over it. That's just not true. Overeating makes you want to eat more. I come from diabetic heritage, I'm borderline, and I still don't want more carbs once I'm done with a meal. I don't know anyone who does. But if I overeat, that's a trigger. Holidays are a perfect example. Overeating causes more overeating. Overeating causes weight gain, as this blog emphasises.

frogfather44 said...

To Anon
"For folks that say: let's not forget that eating carbs just make you want to eat more. Get over it. That's just not true."

It may not be true for you but it is for me.

jennette said...

"The overfeeding studies reported significant individual variability. In other words, some individuals may gain body fat more readily when they overeat carbohydrate, while others may be more sensitive to fat. Or not. We can't really say based on these studies, but it remains possible. "

Individual variability...is this significant enough to warrant a further look? You can't test allergy medications on people with no allergies.

APK said...

Anon, I believe there was a study done that showed that the majority of people will just keep overeating when fed more carbs. But what was found was a minority of people seemed to have some sort of subconscious psychological resistance to it - their bodies did anything to burn of the extra calories and they lost their appetites and were forced fed.
It was a famous, controversial study where they force fed prisoners.

Anyway, that minority of people seems to include me, a skinny guy struggling to put on weight. There's a massive mental block to it.

Anyway, personally I find all of these studies disappoint as someone that wanted to pack on weight fast. Seems the lean guys would take months to put on any noticeable weight at even 50% higher calories.