Thursday, June 28, 2012

New Study: Is a Calorie a Calorie?

A new study in JAMA led by Dr. Cara B. Ebbeling and colleagues purports to challenge the idea that all calories are equally fattening (1).  Let's have a look.  When thinking about the role of calorie intake in body fatness, there are basically three camps:

1.    Calories don’t matter at all, only diet composition matters.
2.    Calories are the only thing that matters, and diet composition is irrelevant.
3.    Calories matter, but diet composition may also play a role.

The first one is an odd position that is not very well populated.  The second one has a lot of adherents in the research world, and there’s enough evidence to make a good case for it.  It’s represented by the phrase ‘a calorie is a calorie’, i.e. all calories are equally fattening.  #1 and #2 are both extreme positions, and as such they get a lot of attention.  But the third group, although less vocal, may be closest to the truth. 
A Little Background on Food Intake, Diet Composition and Energy Expenditure

The energy content of the human body is determined by the amount of energy coming in, minus the energy exiting—simple on paper.  Since body fat is by far the main energy storage site in the body, it follows that the balance between energy intake and energy expenditure determines fat mass, and this has been experimentally confirmed many times.  But here’s the catch—energy expenditure is not always constant.  For example, we know that it increases as a person gains weight, and decreases when a person loses weight (2).  The decrease in energy expenditure with weight loss is caused by two things, 1) a smaller body requires fewer calories for maintenance, 2) a decrease in leptin, which decreases the metabolic rate by acting in the brain (3).

Some people have suggested that the type of food we eat, not just the amount, influences energy expenditure, and in particular that this is related to the diet's carbohydrate content.  In people who are not trying to lose weight (4, 5), or who are being overfed (6, 7), the carbohydrate:fat ratio in the diet has little or no detectable impact on energy expenditure, and if anything it favors carbohydrate, but could this be different during fat loss in people who start off overweight?  This idea has been called the ‘metabolic advantage’, most notably attributed to the low-carbohydrate diet.  The idea here is that you can lose fat eating the same number of calories if carbohydrate is kept low.

I’ve never really weighed in on this because it’s a topic of heated debate, and in any case it’s a fairly academic question.  Why is it academic?  Because previous weight loss studies have shown that if a metabolic advantage exists at all, it’s quite small, because the effect is undetectable in most studies (8, 9, 10).  People who are not associated with the low-carbohydrate community tend to conclude that there's no metabolic advantage when they review the literature (11), although I haven't reviewed it closely myself.  It’s clear that where fat loss is concerned, calorie intake is much more important than the amount of fat or carbohydrate in the diet.  What previous studies have suggested is that low-carbohydrate diets suppress appetite — often resulting in lower calorie intake (12, 13).  The reason for this remains a topic of speculation.  

That being said, I’m actually quite open to the idea that food quality in addition to quantity can influence body fatness, and I would encourage people to think outside the macronutrient box: there are probably many different dietary factors that can have such an effect.  Although this idea hasn’t received much support in the human literature so far, there’s quite a bit of evidence for it in the animal literature.  For example, when we want to produce obesity in rodents we typically use diets that are composed of refined ingredients, high in fat (40-60% of calories), contain some sugar (~10% of calories), and are highly palatable.  These diets are extremely fattening in susceptible strains, but their fattening ability is only partially dependent on increased calorie intake.  If you restrict an animal's energy intake so that it’s the same as rodents on a non-fattening unrefined diet (called ‘pair feeding’), they still gain most of the fat that they would have if you hadn’t restricted energy intake at all (14, 15)!  This suggests that these diets make their bodies ‘want’ to be fat, and they will accomplish this goal by increasing calorie intake and/or by decreasing energy expenditure.  This is related in large part to changes that occur in the brains of these animals (16)

The Study

Enter the recent study by Dr. David Ludwig’s group (1).  This is a really fascinating, some might say groundbreaking, study.  Although we know that differences in dietary carbohydrate and fat content have little or no impact on energy expenditure during overfeeding, in weight-stable people, or during weight loss, we don’t know much about how these impact energy expenditure during weight maintenance after weight loss.  Weight maintenance is critical because it’s where most people’s weight loss efforts fail. 

Contrary to some of the claims I'm sure are being made about this study, it wasn’t actually designed to tell whether fat and carbohydrate per se influence energy expenditure.  What they compared were three distinct dietary patterns that differed in carbohydrate, fat, protein, and other aspects of diet composition, although carbohydrate content was certainly a major difference between groups. 

In this study, they started with overweight and obese volunteers who had lost an average of 14 percent of body weight using a low-calorie diet.  Then they placed them on three different diets, which were precisely controlled by the investigators:
  1. A low-fat (LF) diet  “designed to reflect conventional recommendations to reduce dietary fat, emphasize whole grain products, and include a variety of vegetables and fruits”.  60-20-20 carbohydrate-fat-protein.  I think these people were eating a lot of breads, pastas, etc. 
  2. A low glycemic index (LGI) diet diet designed to “achieve a moderate glycemic load by replacing some grain products and starchy vegetables with sources of healthful fat and low–glycemic index vegetables, legumes, and fruits”.  40-40-20 carbohydrate-fat-protein.  Low glycemic index carbohydrates are those that increase blood sugar less per unit carbohydrate eaten, such as beans, oatmeal, fruit, and sweet potatoes.
  3. A very low carbohydrate (VLC) diet that was “modeled on the Atkins Diet and had a low glycemic load due to more severe restriction of carbohydrate”.  10-60-30 carbohydrate-fat-protein.  This is mostly meat, vegetables, eggs, nuts, and added fats.  They also took a fiber supplement as recommended by Atkins.
After four weeks, they measured energy expenditure, both at rest and over the course of 24 hours.  It’s worth mentioning that they used state of the art techniques to measure these variables.  What they found is that energy expenditure at rest, and over 24 hours, was highest in the VLC group, intermediate in the LGI, and lowest in the LF group—and the differences were substantial, up to 308 calories a day.  A notable limitation of this study is that each diet period only lasted 4 weeks—we don’t know what would have happened to these people after 6 months or a year.

Does this support the idea that there is a ‘metabolic advantage’ to low-carbohydrate diets?  Well, sort of.  It doesn’t change the previous findings that the carbohydrate:fat ratio has little or no impact on energy expenditure during overfeeding, in weight stable people, or during weight loss, but it does suggest that a VLC dietary pattern has a metabolic advantage over a LF diet specifically in the context of weight maintenance after weight loss.  It also suggests that a LGI diet has a smaller but still meaningful metabolic advantage in this setting, and that a LF diet are not very effective in this regard.  It also opens a whole new can of worms for the research world, investigating the effects of diet quality on energy expenditure. 

So should everyone eat a VLC diet for weight loss maintenance then?  Not so fast.  The VLC diet group experienced some troubling hormonal changes that seem to be pretty common with this kind of diet.  There were three main negative changes.  The first and perhaps most troubling was an increase in cortisol, a stress hormone that may contribute to serious health problems over the long term (17).  The second was a decrease in thyroid hormone, which is something that has been observed repeatedly with this kind of diet.  Many of the negative effects that some people develop on long-term VLC diets (constipation, lethargy, poor sleep, hair loss, irritability) could be related to low thyroid function.  This doesn't seem to be as much of an issue with moderate carbohydrate restriction.  The third was an increase in C-reactive protein (CRP), a marker of inflammation and heart attack risk.  Although the paper and media reports make a big deal out of the increase in CRP, it looks quite small to me—I’m not convinced it’s biologically significant. 

The low-fat diet came out looking pretty poor as well.  Energy expenditure was lowest on this diet, and estimated insulin sensitivity was also lowest (although the caveat here is that they didn't directly measure insulin sensitivity).  This is interesting because as they remarked in the paper, this is the dietary advice most people will receive from nutrition authorities.  This adds to the evidence that eating a bunch of whole grain breads and pastas is probably not a great strategy for weight loss maintenance.

Overall, the LGI diet came out looking the best overall.  It’s the least restrictive of the three, conferred a pretty good ‘metabolic advantage’, and was not associated with harmful hormonal changes.  I think this kind of diet would be a reasonable choice for weight maintenance following fat loss.  I’ve been skeptical of the glycemic index concept in the past, and I continue to be, because most controlled studies have shown that in isolation it has little or no impact on body weight or insulin sensitivity (18, 19).  The LGI diet in this study did indeed have a low glycemic index, but since it differed from the other diets in many other ways, we can’t know whether the glycemic index per se was a relevant factor. 

In any case, a diet that focuses on beans/lentils, meats, nuts, fruits, and vegetables at the expense of grains (particularly flours) may be a good choice for weight loss maintenance, and I think this squares well with research coming from other angles.  That being said, there are some major caveats to this study that must be kept in mind:
  1. It was only four weeks long.  We don't know if this difference would have continued in the long run.
  2. The study was not designed to measure long-term changes in fat mass, which is what we're ultimately interested in.
  3. This was done under calorie-controlled conditions, not under free-living conditions as most people would apply these diets.  Under free-living conditions, the main determinant of long-term fat loss seems to be how well you stick to a diet, not which diet you choose (20, 21, 22).
  4. There was a lot of individual variability in this study, confirming once again that everyone is different.  There is no reason to stick to a diet if it's not working for you, just because a study says it works well for the "average person".  Kudos to Drs. Ebbeling and Ludwig for reporting individual data.
Despite these important caveats, I think the results are fascinating and I look forward to more studies on this phenomenon.  If I have time, I may discuss the potential mechanisms for this effect in a future post.

56 comments:

Stabby said...
This comment has been removed by the author.
Chuck said...

i may be wrong but i thought i read that the CRP dropped from 1.75 baseline to .87 for the VLC group. am i wrong?

Richard said...

After three years on low carbs I decided to eat a few more, but not much more. If I need to lose weight I know what to do.

For me, the big difference in the VLC diets compared to the usual American diet is the lack of a rise and then crash of glucose, or leptin signaling, or however we want to describe it, the sensation that you MUST eat, and get very unhappy when you can't. This happens every few hours on the usual American carb intake.

On the other hand, one can remain quite calm when one has had only minimal or no carbs in the last meal or two, or day or two. The sense of needing to eat is present, but it's just something you have to do.

To me this is a huge difference and I have not experienced any of the so called "cravings" for bread or sugar or whatever. Once you experience that sense of calm you don't want to go back to over-consumption of carbs.

I'm not so sure about the thyroid issue as an issue. I didn't have much hair to start with, and many low carb people do a lot of exercise and seem very energetic. For me I exercise six days a week, just as I have done for the last five years or so.

And to an extent a proper low carb diet looks a lot like the Low Glycemic Index diet, as far as I can tell. That is, of course it's a LGI diet at the same time.

My initial approach to the VLC diet was as an experiment, a commitment to about 3 months of VLC. It seemed to work, and so I just kept doing it.

Dave said...

I think researchers are too fixated on how the diet composition determines energy expenditure but they really need to pay more attention to how diet composition affects eating behavior. We know pretty well that humans are fairly consistent with EE when diet composition changes but calories are held constant. This seems to be the outlier study as most metabolic ward studies show no more than a 90 or so calorie metabolic advantage but its due to protein being higher, not lower carbs typically. Even this study has higher protein in the low carb group. That 300 calorie advantage is probably a best case scenario because its not something that shows up in studies all the time.

Lets face it, just about all obese people eat too much, so figuring out how to maximize EE with diet composition is a waste of time. Let's figure out exactly how to give them a diet that is the most satiating so that they eat less calories and don't need to worry about losing weight do to a small metabolic advantage that may or may not exist.

Bethany said...

A post I can finally make sense of. I always read with interest, but am often left puzzled.

Thanks for writing!

Nigel Kinbrum said...

Stephan, you wrote "It’s represented by the phrase ‘a calorie is a calorie’, i.e. all calories are equally fattening."
That's not quite correct. IIRC, the phrase 'a calorie is a calorie' refers to weight, not fatness.

Danielle said...

Thanks for writing such a good review of the study!
I still don't understand how any academic in nutrition can truly believe that a calorie is a calorie. Yes, one unit of energy is still one unit of energy, but once it enters the mouth we have absorption and fermentation in the gut, liver metabolism to deal with, and then once in the bloodstream, who says that calorie will be destined to be used for energy anyway. There are hormonal responses to different macronutrients playing a role and many further downstream effects on metabolism. Saying a calorie is a calorie is being completely blind to how complex human metabolism really is.
I would love to see a study similar to this one that was A) under free living conditions, and B) lasted up to 6 months in length. I think those negative outcomes of the VLC diet need to be investigated further. Many people adopt a VCL diet to loose weight and it obviously works. However, we as a society are always so concerned with immediate and quick outcomes such as weight loss and body composition (rightly so with the obesity epidemic), but what about long term health implications? A balance needs to be reached somewhere and I think the low GI diet does that.

Mike Howard said...

Very good review! I think we tend to get too wrapped up in the low fat vs low carb debate when really protein seems to be the trump card in terms of satiating macronutrients - leading to less food consumption.

What were the protein levels of the VLC diet vs the others? When protein levels are matched, the differences seem to disappear.

Yes, calorie composition can matter and does have different physiological impacts in the system, but calories matter most when it comes to body composition.

Mike Howard said...

Just saw there is a 30% protein in the VLC group vs. 20% in the LGI group. There's your difference right there.

Jenny said...

The LGI diet really was really a Zone diet, judging from the macro nutrient ratios, which is the one that a decent long term study found best for maintenance, too.

The big problem with that kind of diet in free range humans is that it isn't as easy to describe and implement. People can figure out how to apply "don't eat carbs" or "don't eat fat" without pulling out software at every meal. Try doing 40% carb, 30% protein, 30% fat in your head. Much tougher and for the math-impaired (a huge segment of the population, unfortunately) impossible.

Gretchen said...

@Richard

You said, "If I need to lose weight I know what to do." Be careful. Often what worked the first time doesn't work again.

The best way to avoid weight problems is never to have them in the first place. So be vigilant.

Resmungo said...

Problems like CRP might be due more to the food quality on on Atkins-type diet than low carb in general. Swap in grass-fed meats and natural fats for conventional meats and veggie oils and see if these things are still problematic.

Mario Iwakura said...

Just want to add some comments regarding thyroid function on this study.

If thyroid function was impaired, TSH would have increased rather than decreased.

At the same time, total and resting energy expenditure would decrease not increase. Sluggish, not fast, metabolism is a symptom of hypothyroidism.

Since thyroid hormones are involved in carbohydrate metabolism, it's not a surprise that they would decrease if less carbohydrates are eaten...

It's a shame that free T3 and free T4 were not measured.

Razwell said...

The answer is not currently known according to Dr Friedman and Dr Leibel.

More experimentation is needed. Science is a work in progress, but the research is headed in the direction that there seems to be a metablic advantage. It seems this is true. I myself prefer a lower carbohydrate diet.

Only Internet gurus with a vested interest (selling fat loss books) in "a calorie is a calorie" deny what this study showed.

They are all shysters and frauds. Einstein would be displeased with their attitudes. I never understood why these Internet salesmen have such a following and appeal to people. They are not scientists at all.

The days of the caloric hypothesis are numbered. the days of the commercial weight loss industry's dogma will soon be exposed by genuine scientific inquiry which could not make me happier.

I am only interested in getting closer to the truth.

Jason said...

What I don't understand is why people are focusing on a trivial increase in CRP, while HDL rose significantly and Triglycerides fell?

Chuck said...

@jason

i am still not convinced CRP went up. all i can find from the online info is that baseline CRP was 1.75 and after VLC the level was .87. quite a drastic drop. below 1 is commonly accepted as safe.

Jane said...

'..This adds to the evidence that eating a bunch of whole grain breads and pastas is probably not a great strategy for weight loss maintenance. ..'

Were these people really eating a bunch of whole grains? The paper says 'The low-fat diet...was designed to reflect conventional recommendations to reduce dietary fat, emphasize whole grain products, and include a variety of vegetables and fruits.[ref 17]'

Ref 17 says the following:
Consume a variety of fruit, vegetables, grains, low-fat or nonfat dairy products, fish, legumes, poultry, and lean meats
Limit foods high in saturated fat, trans fatty acids, and cholesterol; substitute with unsaturated fat from vegetables, fish, legumes, and nuts
Emphasize a diet rich in fruit, vegetables, and low-fat dairy products
Limit salt to 6 g/d (2400 mg Na) by choosing foods low in salt and limiting the amount of salt added to food
Limit alcohol intake to ≤2 drinks/d (men) or ≤1 drink/d (women)

Where does it say WHOLE grains? The subjects might have been told to 'emphasize whole grains', but the authors obviously didn't think it was that important.

Alex said...

I've been told by a researcher friend that the cortisol increase here is pretty insignificant and well within reference. Not indicative of a stressed state, and silly to mention as a drawback.

Evelyn aka CarbSane said...

Hi Stephan, Unless I'm reading something wrong, bullet point 3. is incorrect: "This was done under very strict calorie-controlled conditions, not under free-living conditions as most people would apply these diets"

According to Figure 1, TEE and physical activity were assessed under free-living conditions. They describe the in-patient assessments as 3 days in duration, so the vast majority of the time I'm left to presume this wasn't a tightly controlled metabolic ward study.

Frankly, I'm appalled by the omission of some basic information in this study. While described as a "controlled feeding study" there is no information provided as to what this really meant. For example, in a study I discussed here, for example, they prepared and provided food for the participants and accounted for uneaten food. In other studies, they at least attempt to assess compliance with 24 hr recall or food logs or something. That there is no mention of any such measures, I'm left to conclude they did not assess compliance.

Also, why no report of the body mass/composition data after each phase? IF on average the LC'ers expended 300 cal/day more, and feeding was "controlled" to be weight stabilizing, were they also eating more? Or did they lose more weight, albeit a small amount?

Why didn't they determine "final" REE and TEE for weight stabilization on the run-in diet and use that as a baseline? This study is like, once you've lost the weight, let's see how macro/quality effects energy expenditure to favor maintenance. Thus (a) baseline to compare these diets should have been vs. post-weight reduction REE on weight-reducing diet, and (b) last at least as long as the weight loss phase to have any meaning at all.

For anyone interested, there's an interesting book out there by Wendy Chant called Metabolism Miracle or something like that. She argues you never want to let your body get complacent -- if you always feed your body the same things it will become efficient at utilizing those foods. Lots of studies and plans out there that cycle macros AND calories that seem to show that "mixing things up" can keep your body on its toes. The VLC was the most drastic departure from "normalcy" and cortisol tells us that story. Is it healthy to do that? Hmmm ... that was one of the reasons I started looking into this for my own edification in the first place. Not sure the answer is black and white.

Clint said...

"Just saw there is a 30% protein in the VLC group vs. 20% in the LGI group. There's your difference right there.

June 29, 2012 5:15 AM"

@ Mike Howard

Your assumption is pretty lazy. We know the TEF (thermic effect of feeding) for protein is roughly 25%. So, on a 2,000 kcal diet, if someone ate 20% of kcals as protein, that would mean they would consume 400 kcals of protein. 100 of those calories would be wasted as heat. If we upped the total amount of protein on a 2,000 calorie diet to 30%, 600 calories would be coming from protein and 150 would be wasted as heat. Going from 20% protein to 30% protein would result in a 50 calorie difference in energy expenditure on a 2,000 calorie diet. Yet the difference between the low fat and low carb group was ~350 kcals. Clearly something is happening beyond the difference in protein ratios. And let's not forget that carbs have a higher TEF than fat, so the difference in TEF between the low carb and low fat would be even less than 50kcals. Clearly, the TEF of different macronutrient compositions isn't the reason behind the difference in EE here.

Stephan Guyenet said...

Good discussion everyone. I see some interesting points being made. Evelyn, I'll have to take a closer look at the feeding protocol but my impression was that they were given all food by investigators in a ward setting. Otherwise I don't know how they could make the claims they do

Beebe-Sweet Family said...

In regards to the feeding - all meals and snacks were prepared by the research team and picked up daily by study participants. So the meals were tightly controlled.

ivat said...

Clint said: "And let's not forget that carbs have a higher TEF than fat, so the difference in TEF between the low carb and low fat would be even less than 50kcals. Clearly, the TEF of different macronutrient compositions isn't the reason behind the difference in EE here."

The authors say something like that at one point. But they also say: ""Alternative explanations for the observed differences in Resting Energy Expenditure and Total Energy Expenditure may involve intrinsic effects of dietary composition on the availability of metabolic fuels [...]"

For example, it might be easier to get carb out of some low-fat milk on the LF diet than fat out of some meat on the LC diet. Some foods cost less energy to digest than others, and my money is on this being behind the difference in metabolic effects between the diets.

Evelyn aka CarbSane said...

@Beebe-Sweet: Where was this stated in the study? I could be blind, it's been a LONG week for me, it could be in supplemental materials but I don't see a link to this protocol. Even the diet descriptions are rather vague.

FWIW Folks, the weight maintenance diets were around 2600 cal/day, the diet comps were per 2000 cal.

Does anyone see anywhere in the study where they assessed compliance or weight after the diet/stabilizing phase?

Peter said...

@Guynet

apparently your critical view in regards to the study stops immeadiately when low-fat diet is at stake. Well, we all have our biases.

According to the study:

"The low-fat diet, which had a high glycemic load, was designed to reflect conventional recommendations to reduce dietary fat, emphasize whole grain products, and include a variety of vegetables and fruits"

If the diet was characterized as high glycemic load-diet it could't include much of the promised whole-grain. In fact the LF diet contained even less fiber than the 40% fat diet, eventhough the 40% fat diet contained more fiberless oils and animal foods. In other words, their low-fat diet had nothing to do with a diet that is recommended by the cholesterol education program. In fact, it was a fiber-poor junk food diet they decided to refer as "low-fat".

High grain, ultra-high carbohydrate diet seems to be working very well in treating obesity, atleast everytime the low-fat is contructed in a way that resembles a diet people in rural Asia, Central-Africa, etc have traditionally consumed. Keyword: whole-plant-foods.

Kempner W, Newborg BC, Peschel RL, Skyler JS.
Treatment of massive obesity with rice/reduction diet program. An analysis of 106 patients with at least a 45-kg weight loss.
Arch Intern Med. 1975 Dec;135(12):1575-84.
PMID: 1200726

KEMPNER W, PESCHEL RL, SCHLAYER C.
Effect of rice diet on diabetes mellitus associated with vascular disease.
Postgrad Med. 1958 Oct;24(4):359-71.
PMID: 13591100

Peter said...

Moreover Guynet,

this study showed nicely the impact of diet to serum lipids, something you have questioned in the past and something you failed to mention in your own analysis. I am sure that after this study, you do not question the diet-to-serum-lipid trend anymore. To spare time and effort I'll quote Don Matesz.

"The total cholesterol during low fat phases was 149, a level associated with a very low risk of cardiovascular disease, compared to 156 for the LG phase and 175 for the VLC phase. These data actually provide another study (of hundreds) supporting the notion that dietary cholesterol raises blood cholesterol. The dietary cholesterol for LF, LG, and VLC phases were respectively 140, 280, and 978 mg per day, and the diets with the higher dietary cholesterol produced higher blood cholesterol in a dose-response fashion. The HDL levels during LF, LG, and VLC phases were 40, 45, and 48 respectively, and this apparently contribute to their claim that the LF diet causes 'an unhealthy lipid pattern.'

However, this reduction of HDL is simply a part of the pattern of lower total cholesterol, as evidenced by the fact that HDL as a percent of total cholesterol did not signficantly differ between phases, at 27%, 29%, and 27% for LF, LG, and VLC phases respectively. Moreover, the idea that a high HDL protects against cardiovascular disease has suffered a major setback with the finding that people who have genetic variations producing naturally higher HDL levels do not enjoy greater protection from cardiovascular disease as a result"

With the data at hand, I find it very interesting that they refer low-fat group as having "unhealthy lipid pattern" as if their interperation of lipid-markers was that of low-carb bloggers... well we've heard crazier stuff from the low-carb papers of Phinney, Westman and Co.

Pranay said...

@Peter: I agree that many cultures consume carbohydrate-heavy and even grain-heavy diets and remain lean, but I think it is the overall intake of micronutrients that matters, which is related to traditional food preparation methods. Correct me if I am mistaken, but Africa populations who are lean and have grain-heavy diets soak and ferment their foods so as to minimize anti-nutrients and maximize the micronutrients. In essence, the food is predigested by bacteria and the body metabolizes it more effectively. Westernized, processed grain products are usually ill-prepared, keeping a lot of anti-nutrients intact and overall nutritional content (as well as the bioavailability of those nutrients) low. Whole-grain bread, pasta, etc. are good examples of these foods. I think Stephan has mentioned this in other posts, but just to reiterate, it is not necessarily grains themselves that are bad (or good, depending on your point-of view) but the overall quality and quantity of nutrients in the diet, which traditional grain-heavy cultures optimize by properly preparing their foods as grains are nutritious enough to solely sustain people without this preparation.

Stephan Guyenet said...

Hi Peter,

Keep in mind that many whole grain foods have the same glycemic index as refined grains. For example, whole grain and white bread have almost identical GI as long as both are made from the same grind of flour, and the same applies to white and brown rice. Whole grains are not as rich in fiber as one might think-- at least not compared to nuts, fruit, and vegetables.

Regarding lipids, once again you're only considering half the picture. The VLC diet increased non-HDL cholesterol, but it also increased HDL cholesterol, with no discernible effect on the ratio. This predicts no significant change in CHD risk according to the most widely accepted model, which is why I left it out.

I encourage you to plug the different group numbers into the Framingham heart attack risk calculator and see what you get.
http://hp2010.nhlbihin.net/atpiii/calculator.asp

Sam Knox said...

We've known for thirty years that T3 is sensitive to dietary carbohydrate, and we know why. One of the functions of T3, along with insulin, is metabolizing glucose. Low-carb diets reduce both T3 and insulin, and for the same reason.

There isn't a shred of evidence that lower T3 from a VLC diet causes any symptom of hypothyroidism, or has any other adverse effect, in anyone without a pre-existing thyroid condition.

http://wp.me/p25oah-7l

Richard said...

One thing I continue to fail to understand is why anyone "defends" carbs. Carbohydrates are not a political constituency. Carbs do not pay someone's living expenses or give gifts. (Or do they?) Carbs don't have feelings, so they don't get offended.

It should be obvious that continuous high consumptions of sugar and wheat flour are not something that nature ever provided for although, as has been pointed out, there is evidence of an on-going grain adaptation. Similarly there is no evidence that PUFA consumption in large amounts was ever possible in any natural state. It takes machinery of varying complexity to produce such foods.

Now this study points out that Energy Expenditure is higher on a "proper" higher fat diet, and so individuals on that diet would, one might assume or conclude, have an easier time maintaining a proper weight.

Surely this cannot be much more than a pleasant confirmation of what we can all see in the world around us. Too many fat people. Eating do-nuts.

Secondly, what is the implication here? Certainly one way of viewing the results is that people who ate too many carb calories felt bad and didn't move around much. Assuming that a "natural" diet is more biased towards higher saturated fat consumption (non-PUFA) then a natural-diet person would have and expend more energy and better maintain a natural weight. That is, not look like an over-fed pig.

It astounds me how minor differences in test results can allow anyone to argue, or even consider for a moment, that levels of processed carb consumption in the context of modern society (not Kitivans, unless you are one) is anything other than a public health disaster.

The solution to the problem is well established, and it is a higher saturated fat diet, with those fat calories taking the place of carb and sugar calories to a large extent. We do not need to know all the details of the metabolism to understand that. These studies are essential, but the experiments, which are not just N=1 at this point, clearly point to metabolic improvements when excess sugar, wheat, and any significant amount of PUFA are eliminated from the diet.

My understanding, and belief, is that some people are far more sensitive to carb consumption than others, in terms of weight gain, and it is easy to see who they are as you go down the street. When I do an eat all I want and anything I want I only gain about 10 pounds. But I don't want even those 10 extra pounds on me. How anyone can bear an extra 50 or more I cannot comprehend.

Isabel said...

I just wanted to mention that the CRP levels did not really rise with the low carb diet. They were just reduced less than with the other diets, but were still lower than the pre-wieght loss baseline. These are the numbers provided by the study:

Pre-weight loss baseline CRP: 1.75 (0.44 to 4.61)
Low fat diet CRP: 0.78 (0.38 to 1.92)
Low glycemic CRP: 0. 76 (0.50 to 2.20)
Low carb: 0.87 (o.57 to 2.69)
So, it is not accurate to say that the low carb diet "raised" CRP as some of the articles published on the media say. The levels are still lower than pre-weight loss, just nos quite as low by a very very small difference (anything under 1 is considered normal CRP)

Peter said...

Thanks for reply Stephen buddy,

"Regarding lipids, once again you're only considering half the picture...."

I tend to think that it's actually you who is thinking "only the half picture".

If you plug in the lipid patterns of Ornish 1990 trial patients in the Framingham and compare them to someone who is on the Atkins diet, the Framingham risk pattern tells us that Ornish fares not-so-good, whereas the actual angiogram gives us totally different picture. Ornish diet actually reverses heart-disease, and Atkins increase your risk of getting it (Atkins himself had 30-40% of his arteries clogged). Hence, one should be quite skeptical with the Framingham risk index, especially while keeping mind everything that has come out in regards to lipid-research during the last years. Do you seriuously think butter consumption (raises HDL) indicates better risk profile in terms of heart disease?

I would choose anyday the lipid profiles of the LF group over the other's, and I believe so would the Framingham score designer Bill Castelli as well:

Heart Disease Risk: Cholesterol and Lipids in 2011
What Do We Really Know?
http://www.prescription2000.com/Interview-Transcripts/2011-02-18-william-castelli-heart-disease-lipids-transcript.html

I think it's clear, elevated HDL in the context of high-fat diets is not a good thing, no matter what the Framingham risk index tells us:

1) Doubt Cast on the ‘Good’ in ‘Good Cholesterol’ (May, 2012)

"I’d say the HDL hypothesis is on the ropes right now,” said Dr. James A. de Lemos, a professor at the University of Texas Southwestern Medical Center.."

http://www.nytimes.com/2012/05/17/health/research/hdl-good-cholesterol-found-not-to-cut-heart-risk.html?_r=2&hp

2)Some HDL, or "Good" Cholesterol, May Not Protect Against Heart Disease (2012)

http://www.hsph.harvard.edu/news/press-releases/2012-releases/hdl-cholesterol-heart-disease.html

3) GOod' HDL Cholesterol Can Also Be 'Bad' (2012)

"the HDL amplified inflammatory reactions several times over and could explain the latent chronic inflammation that is associated with high cardiovascular risk,"

"Lowering the LDL level is therefore still even more important than raising the HDL level."

http://www.sciencedaily.com/releases/2012/01/120113210207.htm

4) HDL Not Always the Good Cholesterol We Think Says University of Chicago Study (2008)

http://seniorjournal.com/NEWS/Health/2008/20081201-HDLNotAlwaysTheGood.htm

5) Consumption of saturated fat impairs the anti-inflammatory properties of high-density lipoproteins and endothelial function

"Consumption of a saturated fat reduces the anti-inflammatory potential of HDL and impairs arterial endothelial function. In contrast, the anti-inflammatory activity of HDL improves after consumption of polyunsaturated fat. These findings highlight novel mechanisms by which different dietary fatty acids may influence key atherogenic processes"

http://www.ncbi.nlm.nih.gov/pubmed/16904539

The patients with FH usually end up with athrosclerosis at very a young age even despite that the only risk marker they have non-optimal is the LDL. HDL, triglycerides, C-protein, etc no matter what they are, won't be helping their cause. This fact alone should reveal the hiearchy of the biomarkers.

Peter said...

Thanks for reply Stephen buddy,

I think it's you who "do not see the whole picture". If you plug in the lipid patterns of Ornish trial patients to Framingham score table and compare them to someone who is on the Atkins diet, the Ornish fares not so good in comparison while the clinical reality is completely different as measured by the angiogram.

Do you seriously think that butter consumption (elevates HDL) gives us better risk profile against CVD and CHD?

I think it's rather clear that elevated HDL in the context of low-carb diets is not a good thing. I'd choose the lipid profiles of the LF group anyday over the lipid profiles of the others, and I think the designer of the Framingam risk score, Bill Castelli, would do the same:

Heart Disease Risk: Cholesterol and Lipids in 2011
What Do We Really Know?
http://www.prescription2000.com/Interview-Transcripts/2011-02-18-william-castelli-heart-disease-lipids-transcript.html

Peter said...

1) 'Good' HDL Cholesterol Can Also Be 'Bad' (2012)

"the HDL amplified inflammatory reactions several times over and could explain the latent chronic inflammation that is associated with high cardiovascular risk,"

"Lowering the LDL level is therefore still even more important than raising the HDL level."

http://www.sciencedaily.com/releases/2012/01/120113210207.htm

2) Some HDL, or "Good" Cholesterol, May Not Protect Against Heart Disease (2012)

http://www.hsph.harvard.edu/news/press-releases/2012-releases/hdl-cholesterol-heart-disease.html

3) HDL Not Always the Good Cholesterol We Think Says University of Chicago Study (2008)

http://seniorjournal.com/NEWS/Health/2008/20081201-HDLNotAlwaysTheGood.htm

4) Doubt Cast on the ‘Good’ in ‘Good Cholesterol’ (May, 2012)

"I’d say the HDL hypothesis is on the ropes right now,” said Dr. James A. de Lemos, a professor at the University of Texas Southwestern Medical Center.."

http://www.nytimes.com/2012/05/17/health/research/hdl-good-cholesterol-found-not-to-cut-heart-risk.html?_r=2&hp

5) Consumption of saturated fat impairs the anti-inflammatory properties of high-density lipoproteins and endothelial function

"Consumption of a saturated fat reduces the anti-inflammatory potential of HDL and impairs arterial endothelial function. In contrast, the anti-inflammatory activity of HDL improves after consumption of polyunsaturated fat. These findings highlight novel mechanisms by which different dietary fatty acids may influence key atherogenic processes"

Jane said...

@Richard
'..One thing I continue to fail to understand is why anyone "defends" carbs. Carbohydrates are not a political constituency. Carbs do not pay someone's living expenses...'

I will defend carbs to my last gasp. Carbs DO pay my living expenses, because they're so cheap. 30 years ago I ate a 'normal' diet (actually very healthy by most standards) and was always hungry, always dieting. I changed to a diet based on whole grains and dairy (high carb AND high fat! gasp) and I have not experienced hunger since then. I love my food, but I never crave it.

This is the secret of weight loss, in my experience, and it depends on the proper balance between macronutrients and micronutrients. Whole grains + dairy + fruit/veg provides that balance. There are other ways to get it, obviously.

gunther gatherer said...

I though Don Matesz did a good job of tearing this apart:

http://donmatesz.blogspot.fr/

I think we can estimate a diet's quality by its fiber content. Where was the fiber in the low-fat diet supposedly based on fruits and vegetables?

Razwell said...

Calories have everything to do with how much energy is liberated from *burning* a substance. Calories have very little to do with biological processes, which do not involve combustion.

The outdated , down and out, down for the count Caloric Hypothesis considers food for its combustive chemical eneregy and completely ignores what actually happens to food molecules in the body.

Shysters from the equally fradulent commercial weight loss industry who make their living duping the public on the Internet will never admit this.

Overeating, of course is bad for health, but the phenomenon of morbid obesity is far mor ecomplex.

We are finally starting to actually get to the heart of obesity. The first step is to DISCARD the Calorc Hypothesis. There is more than enough evidence for this now.

Genuine science never stands still and it is moving in the completely OPPOSITE direction from the simplistic and outdated Caloric Hypothesis model of obesity. This does not mean, however, that we understand obvesity well. We have vast oceans of unknwons to discover. What we knwo about obesity is pathetically paltry.

Science has convincingly shown that obesity is NOT "the passive accumulation of calories" OR that "fat tissue is an inactive storage despot". In fact, fat tissue is a genuine endocrine organ as Dr Jeffrey Friedman and Dr. Leibel have shown .

The more we move away from Internet shysters the better off we ALL will be.

cliff said...

If you look at the actual graph some peoples TEE decreased going from LF to LC

http://anthonycolpo.com/?p=3680

marchwinds said...

Should we be at all suspicious that Dr. Ludwig is a big advocate of the low glycemic diet, which, lo and behold, fares the best in this study? Or am I being too cynical?

George Henderson said...

I liked this study, and Dr Lugwid doesn't oversell the results.
Question; if we burn off an extra 300 kcal as heat on VLC, why don't we just increase our food intake to compensate? I mean, how does this result in weightloss any differently from, say, exercising more, or eating less?
I know it DOES in fact make a difference, but not through a direct counting-calories mechanism is my guess; rather, through hormonal effects on appetite, and restorative effects of ketone bodies on nerves involved in energy balance.

M. said...

Very informative post :) Thanks!

Deirdre said...

Great information - as usual! Thank you!

Jim said...

My personal experimentation shows that the best carbohydrate level to maintain low fat mass matches my glycogen usage, which is low unless I exercise intensely for prolonged periods.

Tom A said...

http://www.members.shaw.ca/hsri/same-calories.htm

Greg said...

Stephen, thanks for a very balanced and clear presentation. These results are interesting, but I wonder about their real significance. In my personal experience, it takes more than four weeks to get fully adapted to a high fat, low carb diet. I suspect the changes observed (both good and bad) on the VLC diet may disappear after a longer adaptation period, and of the three diets studied, the VLC arm likely required the most adaptation (e.g. gut flora changes, bile acid production, ketone metabolism, etc.). This might also explain why longer term studies generally show some level of weight regain on all diets, including VLC diets.

Drew Stearns said...

@Jim

I do the same thing and it works great.

Kindke said...

Things like basal metabolic rate and thermic affect of food do not predict adiposty.

Do your research folks.

James Krieger said...

I did a thorough critique of this study for my Weightology Weekly subscribers, uncovering 23 major problems with it. Bottom line is that I do not consider the study results reliable at all, and it should be taken with a grain of salt. I'm surprised it actually made it past peer review, especially in JAMA.

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Can you please explain what are they call "negative calories"? I am Dorothy of California Health Plans.

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Helpful article. A lot of people mistook calories for being fattening, it might be but its essential for our body to produce energy. Don't worry calories will be burn as we try to use up our energy.