Diet, weight loss and body composition changes

This is an unfortunately long post, and I apologize for it, but the reason is that I find all this so darn interesting.  Hope you do to.

A little while back I looked closer at some of the science behind diet, weight loss and body re-composition. I have heard people say on several occasions that a low carbohydrate diet will prevent loss of muscle mass and that all weight lost is fat. So I wanted to find out once and for all what really happens with our body when we lose weight. I’ll show you some of the data, and although these studies are not the only ones, I am confident that the studies presented here give a satisfactory accurateness

So there is much debate about what happens to our body composition when we lose weight and perhaps especially when we do it using a low carbohydrate diet. This quote is from Sachiko T. et al 2001. Dietary Protein and Weight Reduction: A Statement for Healthcare Professionals From the Nutrition Committee of the Council on Nutrition, Physical Activity, and Metabolism of the American Heart Association:

Some popular high-protein/low-carbohydrate diets limit carbohydrates to 10 to 20 g/d, which is one fifth of the minimum 100 g/d that is necessary to prevent loss of lean muscle tissue.

Clearly the AHA suggests that we will lose muscle tissue by going low carb. In my school we used the exercise physiology textbook from McArdle, Katch and Katch (2007) which said this:

…low carbohydrate diet sets the stage for a significant loss of lean tissue as the body recruits amino acids from muscle to maintain blood glucose via gluconeogenesis.

Once again, low carbohydrate dieting does not seem a good idea if we want to preserve muscle mass while we lose fat mass.

But the questions remains unanswered; how much muscle mass do we lose if we go low carb and can we do anything to prevent a potential loss of muscle tissue?

Let us look at some studies and see what they tell us.

Studies
This study from Bonnie Brehm and coworkers compared a low carbohydrate diet to a low fat diet:

All participants in the above study were women and they were obese. Dietary energy content was reduced in both diets and body composition was measured using Dual Energy X-ray Absorptiometry (DEXA). As you can see, weight loss was greater with low carb, but so was loss of lean body mass (LBM) and the percentage loss of LBM was not much different between diets. 
Here’s another study:
This was a crossover study where all the participants tried two different diets in random order. The results are given under:
As is usually the case in weight loss trials, the men lost more weight than the women. And once again low carb caused a greater weight loss, but also quite the loss of lean body mass. The women eating low fat seemed to lose the greatest percentage LBM, which is also a recurrent theme in weight loss trials. 
Next, here’s Kelly Meckling and coworkers:
One of the goals in this study was for the low fat group to reduce their calorie intake to the naturally reduced level of the low carbers. Weight loss did not differ between groups, but loss of LBM was significantly larger in the low carb group and over 25% of the LC weight loss was lean body mass. Body composition was measured using bioelectrical impedance analysis (BIA).
Next, as study from William Yancy and coworkers from 2004:
  
Weight loss with low carb was double that of low fat and this time loss of fat free mass (FFM) was actually quite larger in the low fat group. LBM is what is left if we remove fat mass and skeletal mass. Fat free mass is, not surprisingly, total mass minus fat mass. LBM and FFM are used interchangeably. 
It seems that loss of non-fat mass is common, regardless of diet, but we need to look at some more studies to get a clearer picture.
Here’s one from down under, from Manny Noakes:
This is a short study, but with 83 participants. The results are pretty similar, both when it comes to weight and LBM loss, but in both diets around 30% of the lost weight was LBM and that is rather much.
Another one from Australia. Here’s Jennifer Keogh and coworkers:
Both diets were 30% energy restricted and designed to be isocaloric. Once again there was a significant loss of fat free mass with both diet strategies.
Jeff Volek brought us this study in 2008:
An Atkins type diet was compared to a regular calorie restricted low fat diet in 40 men and women. Weight loss was greater with low carb, but so was loss of LBM. So far, there seems to be little truth to any claim that low carb preserves LBM.
This next one is another crossover study:
Alexandra Johnstone and coworkers showed us yet again that weight loss is greater with low carb, but that so is loss of FFM. Notice that this is a study of men only and so the percentage loss of FFM is much smaller than in studies of women.
One last study. Third one from Australia, this time by Grant D. Brinkworth:
118 people participated in this eight week study and were scanned with DEXA. Weight loss was greater with low carb and both groups lost about 20% FFM.
To summarize, loss of fat mass is greater with LC than LF diets. Loss of LBM is common on both LF and LC diets, but as we will see, not obligate. But there are some considerations to make first.
Considerations
First of all, any loss of water will usually be considered LBM and so if there is a difference in water loss between diets, this will affect loss of LBM/FFM. Carbohydrate restriction usually does cause a greater loss of body water, at least in the initial phase of the diet. Loss of glycogen with low carb will cause a parallel loss of water and so there is reason to expect a larger loss of LBM with low carb, and we need to remember that LBM is not a measure of muscle proteins.  
Contradictory findings
Although loss of LBM is clearly common on low carb diets, there are studies suggesting that such a loss can be avoided.
In a very small crossover study by Benoit et al from 1965 we can see the obvious advantage of low carb dieting compared to fasting:
Notice the difference in LBM loss. One likely advantage of carbohydrate restriction is that the combination of adequate protein intake and high ketone body production spares muscle proteins from being used to produce glucose. The Benoit study is small, but it suggests that loss of LBM is not a necessary consequence of low carb dieting.
And look at this one:
In this study of twelve men, LBM increased during the diet period, even though there was no change in the exercise pattern of the subjects. It is results like these, which sometimes appear, that suggests that it is possible to lose weight in a way that spares muscle tissue. In another very small study of very obese adolescents, similar results were found:
After eight weeks of a very low calorie ketogenic diet, lean body mass increased by almost 1,5kg while 15kg of fat was lost.
So I think it’s time to ask what the difference between these few studies where LBM increases (in spite of water loss) and the RCT’s where a low carbohydrate diet always leads to some LBM loss. But remember also that not all LBM is functional LBM. That is, we expect some loss of LBM and some LBM can be lost without negative consequences. We must remember to keep our feet on the ground, there is no problem with some loss of LBM with large losses of fat mass.
To make a long story short, there are some important factors we can manipulate in order to reduce loss of LBM. Being a man is perhaps the most effective. Men lose more fat and less LBM when they lose weight. It’s just the way it is. But both men and women can increase their protein intake. In many of the RCT’s in this post, average protein intake was low, often around 1g/kg body weight/day. The optimal intake is probably closer to 1.8g/kg/day (severely overweight people should use ideal body weight instead of actual body weight).
Several studies have found a correlation between protein intake and LBM loss. James Krieger wrote this in 2006:
  
And he concluded thusly:
In a very recent review article, Stuart Philips and Luc van Loon has this to say:
The thing with carbohydrate restriction is that is causes a greater fat loss and greater LBM loss than low fat strategies, but the end result is that low carb thus causes a greater reduction in body fat percentage and so the greater change in body composition. To optimize the results, protein intake should most likely be kept at >1,5g/kg/day. Here’s another quote from Phillips and van Loon:

There is also the matter of sodium and potassium that might play a part in the results. Potassium is an important intracellular ion in our muscles and adequate potassium is important for creating an anabolic environment. The trouble with ketosis or severe carbohydrate restriction is that it causes our kidneys to excrete sodium and unless that sodium is properly replaced the kidneys compensate by excreting potassium. In short, when optimal body composition changes is the goal, or optimal performance, salt intake is important and should be a good deal higher than the daily recommended intake.

In addition to minding our protein and salt intake, we can of course also do resistance exercise in order to increase lean mass retention or even increase lean mass while reducing fat mass. It is, not surprisingly, well documented that resistance exercise, as a part of weight loss, is very effective at reducing lean mass loss, regardless of diet. But in order for resistance exercise to yield optimal results, protein and salt intake must be optimized.  
Richard Wood and coworkers just published results from a study where overweight older men were put on two different diets with or without resistance exercise. Here are the results:
Even though the results favor both low carbohydrate dieting and resistance exercise, I must say that I was surprised at the amount of FFM loss in the low carbohydrate and resistance exercise group, even when considering that some is water loss. After 12 weeks I would have suspected FFM to have increased. But there are once again some factors to consider. First of all, the mean age of the participants were 60 years. This may have caused the results to be smaller than if younger men participated. Also the resistance exercise was not very heavy, it could have been a good deal heavier and it is likely that muscle hypertrophy would then have been greater.
Donald K. Layman and coworkers compared the effects of two different diets varying in protein and carbohydrate content, with or without resistance exercise. The graphs on the left are women and the ones on the right are men:

Clearly, both increasing protein/decreasing carbohydrate and resistance exercise improve body composition changes. The low carbohydrate diet in this study was not very low. Average carb intake during the intervention was 141g in LC and 126g in LC+RE. Protein intake was 110g and 102g respectively.

I’d like to compare the results of a study I conducted in 2010 with that of a study from Donnely from 1991:

These are two very different strategies. In our study the participant were told to be in dietary ketosis, but could eat as much as they liked. In Donnely’s study calories was severely restricted. Also in our study the participants exercised twice a week, whereas in Donnely’s they exercised four times per week (resistance exercise). They are both effective strategies both for losing weight and changing body composition, so it is up to us what we prefer. I for one would like to eat as much as I please and not have to exercise that much to get the results I want.

The conclusion
Loss of LBM with weight loss is common but not obligate. A low carbohydrate diet is no grantee for all weigh loss being fat. In order to achieve optimal body re-composition one should reduce carbohydrates, make sure to eat enough protein and salt, and do regular heavy resistance exercise. The results one can achieve are quite astonishing.

Overfeeding – Calories count, but don’t bother counting them

«The upper two sets of figures show Mr. A. Levanzin of Malta, Dr. Benedict’s celebrated subject, before and at the completion of his fast. ‘About two and a half years ago, while I was over-eating, obese, neurasthenic, pessimistic and with a shattered nervous system, I chanced to read. . . an article about fasting. It was a flash of light that struck me vividly. It indicated to rue the right path to health and happiness. . . Today is the 31st and last day of it. . . I am feeling very well, very uplifted, and. . . do not feel yet any trace of hunger. I did not feel the least uncomfortable sensation except the bad taste of my coated tongue. I hope that a great benefit to my health shall accrue from it’. The lower two sets of figures show Mr. Winston Morris, one of the subjects of the University of Vermont study of experimental obesity before and after gain in weight. For the initial 75 days his average calorie intake was 6,700 (5,400 kcal/70 kg body wt) and for the following 60 days 10,200 kcal (8,300 kcal/70 kg). During both periods the composition of the diet by weight was approximately: protein, 17%, fat, 28% and carbohydrate, 52%. In contrast to Mr. Levanzin, he does not recommend his regimen as the right path to health and happiness.» [1]

Even among individuals who appear to combine dietary and lifestyle habits believed to promote the development of obesity, weight gain over the years is much slower than one would expect considering the pleasure associated with eating, the loose regulation of daily food intake, and the great tolerance for excessive intakes. [2]

It is not strange that the matter of overfeeding has lodged itself at the core of many nutrition debates. Overfeeding address the very question of what makes us fat and how we fatten.

But overfeeding studies do not fit nicely into the «calories inn – calories out» dogma. In fact, the finding that overfeeding does not generally cause long term overweight, is used to argue that it is what we eat, as opposed to how much, that determines how much weight we gain. The logic is that what we eat affects how much we eat, how much we burn and how we feel and so on. If different types of food affect how energetic we feel, as we know they can, and this effect is independent of energy content, then calories do not seem worth counting.

Because changes in RMR and thermic effect of food were small, the resistance to weight and fat gain with overfeeding was attributed to changes in spontaneous physical activity… [3]

The whole subject of overfeeding is extremely interesting, but it requires some careful tongue in cheek navigation through a minefield of twisted logic and rhetoric traps. For example, is overfeeding even relevant to the normal physiology of overweight and obesity? And even if subjects in studies are not «force fed» but rather make a small effort to overeat, can it tell us what causes obesity? And if we accept that dietary composition matter in a normal diet, then composition matters in overfeeding as well. Do we then know what component of the diet is responsible for weight gain?

Energy
Body weight is definitely regulated, and as it seems, quite tightly so. Most people are relatively weight stable most of the time, despite large variations in day to day energy expenditure and energy intake. An age-related drift in body weight has been estimated to about half a pound per year. David Weigle calculates that if the cost of depositing this ½ pound is 1560 kcal and that the caloric intake of an average individual is approximately 900,000 kcal per year, this weight gain represents an excess energy consumption of less than 0.2% [4]. This number is simply too small to conclude that body weight is something we are in control of. Counting calories just does not make any sense, because our body is in charge, not our mind.

Individuals who gain the less body weight during overfeeding are those who experience a greater increase in total energy expenditure. [5]

But the fact that body weight is tightly regulated does not mean it is unchangeable. We know it’s not. Losing weight can be quite easy. This means that the mechanisms that regulate body weight (or rather fatness) are the very mechanisms we alter when we lose weight and so those mechanisms are easily manipulated.

Gaining weight, at least in a speed equaling the speed at which we can lose weight, is close to impossible. The main reason is that overfeeding makes us full. A near complete suppression of appetite has been observed in both human and animal subjects [1,4,6,7]. For example, in one study, normal weight men were overfed by 1000 kcal per day for 21 days. This produced a mean fat gain of 79 grams per day. The voluntary caloric intake over the first 10 days after the end of the overfeeding, was reduced by 476 kcal per day relative to baseline.

In one study where rats were overfed to achieve twice the body weight of control animals, two obese rats were kept at a temperature of 5 degrees Celsius (which is a temperature that requires the rats to burn more energy for heat production), and yet did not consume food for 11 and 16 days. The animals started eating again once they were down to their original weight.

This graph shows the feeding and weight response in three tube overfed macaques. Overfeeding is during the solid bar. Food intake goes down during overfeeding and increases once the animals approach baseline weight

Extra energy ingested during overfeeding does not simply become stored. That is, some does. But one common consequence of overfeeding is increased energy expenditure. In a study by Leibel and coworkers, both obese and lean subjects were overfed and kept at 10% increased bodyweight compared to normal. This caused an increase in energy expenditure of 9kcal per kilo fat free mass in the lean and 8kcal in the obese [8].

Hence, the hypothesis that higher food intake may be the cause rather than the consequence of higher 24-h carbohydrate oxidation rates cannot be positively ruled out. [9]

Because not all extra energy is stored, weight changes in response to overfeeding are generally small. Still, large individual variation is common [10-12] and this variation is important to consider. There are many proposed mechanisms for the individual variation, such as different mitochondrial efficiency, compliance to diet and differences in digestion. Of course, the amount of overfeeding is often calculated based on self-reported food intake prior to overfeeding. This may also be a source of error and underreporting may explain some of the individual differences. People with a family history of diabetes experience larger detrimental effects from overfeeding than people without [13], which illustrates how our genes determine our potential for disease and weight gain.

One of the more famous of overfeeding studies, which resulted in a pile of articles, was conducted by Claude Bouchard in 1990 [14]. To see if there really were differences in how individuals responded to overfeeding and to see if this difference was due to different genotypes, he used 12 pairs of monozygotic twins. They were overfed by 1000 kcal, six days a week for 84 days. On average this resulted in 8.1kg (2,7kg of which was lean body mass) gained weight. But the range was from 4,3kg to 13,3kg. The twins gained the same amount of weight, in the same way, and thus showed the importance of genes. But the large variation between twin pairs in response to overfeeding is interesting.

The Bouchard study also found that the twins with the most type 1 muscle fibers, the slow fat burning type, gained the least fat. It might seem that skeletal muscle oxidative capacity in part predicts weight gain [15]. 4 months after the overfeeding, the twins had lost 7 of the 8 kilos gained, but at a 5 year follow-up mean weight had increased by 5kg. This was however likely the result of the younger twins (youngest pairs were 19y) adding some normal late pubertal weight.

And, although Bouchard and coworkers seemed somewhat surprised by it, the study found that there was no correlation between the total energy ingested and weight gained.

No current treatment for obesity reliably sustains weight loss, perhaps because compensatory metabolic processes resist the maintenance of the altered body weight. [8]

Diet composition
In overfeeding, as in normal feeding, results depend on the type of nutrient consumed. Overfeeding on carbohydrate affects the body differently from overfeeding on fat and different fats and carbohydrates will, theoretically, affect us differently.

One of the most extreme overfeeding rituals is that of the Cameroonian Guru Walla. In the Guru Walla, young men consume a diet made of red sorghum and cow milk (makes up over 95% of calories). The young men isolate themselves in different houses with a female attendant devoted exclusively to the preparation of Guru Walla meals. The diet and exclusion is supposed to lead to a certain level of purity. The men eat every 3 hour for 60 days, during which time body-weight can increase by an average of 17kg [16]. The ritual food is truly a high carb diet, with 70% CHO, 15% fat and 15% protein. Despite their large weight gain, the excess weight is lost after the ritual ends.

Patrick Pasquet writes about the long term effects of the Guru Walla: «Thus, 2.5 y after cessation of fattening there was a spontaneous return to initial body weight and body composition of the overfed subjects.» Pasquet almost had his nice stats ruined by one Cameroonian getting married and not losing as much weight as the other subjects: «Eight of them did not change daily life patterns and food habits in relation to the pre overfeeding period. One subject got married in the meantime; interestingly, for this subject some persistent overweight was left (6.7 of a 19.7kg gain).» [17] Marriage is of course a common accelerator of weight gain.

In a crossover study from 1995, led by Tracy Horton [18], lean and obese subjects were overfed on either fat or carbohydrate for 2 weeks. All subjects gained a similar amount of weight on both overfeeding strategies, and post overfeeding body weight gradually came back to baseline in both groups. But measurements showed that energy expenditure was increased more with carbohydrates than fat. This is likely because the body tries to burn off as much glucose as possible to keep from getting dangerously high blood glucose, while increased fat intake is not as dangerous, and there is thus less need for increasing oxidation of it. There were also indications of more energy being stored with fat overfeeding than with carb overfeeding. Lean and obese subjects responded similarly to overfeeding, although not surprisingly, the obese had a higher proportional oxidization of carbohydrate on both strategies.

The obese are commonly recognized by the fact that they are carbohydrate burners rather than fat burners [19]. Although the researchers does not mention it, table 3 shows that carbohydrate overfeeding caused greatly increased fasting insulin concentration in both lean and obese subjects. But fat overfeeding halved insulin in the lean and doubled it in the obese. It is also strange that the lean subjects had much higher insulin before fat overfeeding than before carbohydrate overfeeding. As this was a crossover study the results should be interpreted with caution.

Danish researcher Ole Lammert, and colleagues, also compared carbohydrate and fat overfeeding [12]. No significant difference in carbohydrate (78% carbohydrates, 11% protein, 11% fat) and fat 58% fat, 11% protein, 31% carbohydrate) were found after 21 days overfeeding. Both groups gained 1,5kg of weight.

When we eat carbohydrates, much can be stored in muscles and liver as glycogen, but as soon as these stores are saturated, carbohydrate oxidation increases and de novo lipogenesis (conversion of carbohydrates to fat) increases [20]. In one study, extreme carbohydrate overfeeding caused subjects to burn 400g of carbs per day, without exercising. And resting energy expenditure increased by 35%. Fasting glucose levels did not increase, which shows the body’s great ability (in lean subjects) to convert glucose to fat so as to keep blood glucose low. In addition, the study showed that going from a low fat diet to eating a high carb (86%) overfeeding diet, can bring your triglycerides from 0,8 mmol/l to a whopping 8,6 mmol/l, which is an astonishing feat.

Body weight change in both lean and obese subjects in the Horton study. As usual, once overfeeding is finished, food intake and body weight goes down. You could theorize that the reduction in body weight post overfeeding is caused by the subjects wanting to lose the newly gained weight. But as the reaction is the same in many other animal species, it is likely a natural physiologic response.

Body composition
It is interesting that overfeeding also can cause quite an increase in lean body mass, sometimes half the weight gained [11,12]. Only 64-75% of the 17 kg weight gained during the Guru Walla is fat mass [16]. In the Vermont prison overfeeding study, inmates increased their body weight by 16,2kg of which 10.4kg was determined to be fat. This does not mean that overeating is a good or way to build muscles, but there is much indication that if you want optimal muscle growth, you shouldn’t hold back on food intake.

Weight gained as fat can be either hyperplasia (new cells) or hypertrophy (increased cell size). A 2010 study found that 8 weeks overfeeding in 28 healthy normal weight adults led to an obvious increase in fat cell size, but also an increase in fat cell number [21].

Conclusion
Weight gain from overfeeding is not large. In fact, we could say that overfeeding works about as well at increasing body weight as energy restriction works at decreasing it. People do gain weight by voluntary overfeeding themselves or being force fed, but as soon as subjects return to their regular diet, the newly gained weight is quickly lost. This finding is one important reason the set point hypothesis emerged. What part of the diet is mostly responsible for the weight gain is difficult to say, but it is not likely easy to overeat on a low carbohydrate diet. Overfeeding is not healthy, and one important reason for the observed increased energy expenditure, is likely the body desperately trying to keep blood glucose down.

Overfeeding pushes the body’s equilibrium towards increased fat storage, but in animals and humans alike, once normal feeding commences, the equilibrium is once again restored at the original body weight. It is also clear that although most of the surplus energy is stored, quite a large part is used to increase energy expenditure, and so it is difficult to calculate weight gain or fat gain from calories consumed as food. In other words, more energy (calories) increases body weight, but the processes of energy storage and expenditure are too complex for it to make any sense to count calories.

References

1. Sims EA, Danforth E Jr, Horton ES, Bray GA, Glennon JA, Salans LB: Endocrine and metabolic effects of experimental obesity in man. Recent Prog Horm Res 1973, 29: 457-496.

2. Flatt JP: Issues and misconceptions about obesity. Obesity (Silver Spring) 2011, 19: 676-686.

3. Galgani J, Ravussin E: Energy metabolism, fuel selection and body weight regulation. Int J Obes (Lond) 2008, 32 Suppl 7: S109-S119.

4. Weigle DS: Appetite and the regulation of body composition. FASEB J 1994, 8: 302-310.

5. Tappy L: Metabolic consequences of overfeeding in humans. Curr Opin Clin Nutr Metab Care 2004, 7: 623-628.

6. Roberts SB, Young VR, Fuss P, Fiatarone MA, Richard B, Rasmussen H, Wagner D, Joseph L, Holehouse E, Evans WJ: Energy expenditure and subsequent nutrient intakes in overfed young men. Am J Physiol 1990, 259: R461-R469.

7. Bessesen DH, Bull S, Cornier MA: Trafficking of dietary fat and resistance to obesity. Physiol Behav 2008, 94: 681-688.

8. Leibel RL, Rosenbaum M, Hirsch J: Changes in energy expenditure resulting from altered body weight. N Engl J Med 1995, 332: 621-628.

9. Pannacciulli N, Salbe AD, Ortega E, Venti CA, Bogardus C, Krakoff J: The 24-h carbohydrate oxidation rate in a human respiratory chamber predicts ad libitum food intake. Am J Clin Nutr 2007, 86: 625-632.

10. Stock MJ: Gluttony and thermogenesis revisited. Int J Obes Relat Metab Disord 1999, 23: 1105-1117.

11. Forbes GB, Brown MR, Welle SL, Lipinski BA: Deliberate overfeeding in women and men: energy cost and composition of the weight gain. Br J Nutr 1986, 56: 1-9.

12. Lammert O, Grunnet N, Faber P, Bjornsbo KS, Dich J, Larsen LO, Neese RA, Hellerstein MK, Quistorff B: Effects of isoenergetic overfeeding of either carbohydrate or fat in young men. Br J Nutr 2000, 84: 233-245.

13. Samocha-Bonet D, Campbell LV, Viardot A, Freund J, Tam CS, Greenfield JR, Heilbronn LK: A family history of type 2 diabetes increases risk factors associated with overfeeding. Diabetologia 2010, 53: 1700-1708.

14. Bouchard C, Tremblay A, Despres JP, Nadeau A, Lupien PJ, Theriault G, Dussault J, Moorjani S, Pinault S, Fournier G: The response to long-term overfeeding in identical twins. N Engl J Med 1990, 322: 1477-1482.

15. Sun G, Ukkola O, Rankinen T, Joanisse DR, Bouchard C: Skeletal muscle characteristics predict body fat gain in response to overfeeding in never-obese young men. Metabolism 2002, 51: 451-456.

16. Pasquet P, Brigant L, Froment A, Koppert GA, Bard D, de G, I, Apfelbaum M: Massive overfeeding and energy balance in men: the Guru Walla model. Am J Clin Nutr 1992, 56: 483-490.

17. Pasquet P, Apfelbaum M: Recovery of initial body weight and composition after long-term massive overfeeding in men. Am J Clin Nutr 1994, 60: 861-863.

18. Horton TJ, Drougas H, Brachey A, Reed GW, Peters JC, Hill JO: Fat and carbohydrate overfeeding in humans: different effects on energy storage. Am J Clin Nutr 1995, 62: 19-29.

19. Zurlo F, Lillioja S, Esposito-Del Puente A, Nyomba BL, Raz I, Saad MF, Swinburn BA, Knowler WC, Bogardus C, Ravussin E: Low ratio of fat to carbohydrate oxidation as predictor of weight gain: study of 24-h RQ. Am J Physiol 1990, 259: E650-E657.

20. Acheson KJ, Schutz Y, Bessard T, Anantharaman K, Flatt JP, Jequier E: Glycogen storage capacity and de novo lipogenesis during massive carbohydrate overfeeding in man. Am J Clin Nutr 1988, 48: 240-247.

21. Tchoukalova YD, Votruba SB, Tchkonia T, Giorgadze N, Kirkland JL, Jensen MD: Regional differences in cellular mechanisms of adipose tissue gain with overfeeding. Proc Natl Acad Sci U S A 2010, 107: 18226-18231.