Caveman Doctor recently received many emails (whatever an email is) and even some questions in the hallways at work concerning a recent article where they compared low and high protein diets.  Caveman Doctor wasn’t planning on doing a post today; however, he thought it was important to address this article.

Effect of Dietary Protein Content on Weight Gain, Energy Expenditure, and Body Composition during Overeating

This study was published yesterday on the online version of the Journal of the American Medical Association (JAMA) by Dr. Bray and authors¹.  In the study, 25 patients were followed in the “metabolic unit” of the hospital for 10-12 weeks.  During the last 8 weeks, the 25 patients were split into three groups, each consuming 954 more calories per day:

1. Low protein diet: 6% of energy from protein, 52% fat, and 42% carbs
2. Normal protein diet: 15% of energy from protein, 44% fat, and 41% carbs
3. High protein diet: 26% of energy from protein, 33% fat, and 41% carbs

 
Pausing for a moment to evaluate these diets, the normal protein diet is actually likely still on the lower side when compared to what we as humans have been consuming for the past two million years^2-5.  The diets are all high in carbohydrates, which unfortunately is standard operating procedure nowadays when it comes to nutrition.  Also, only 25 patients were in the study, and when divided into three groups, the statistical validity of the study becomes concerning.  Nonetheless, the authors should be commended in their efforts, especially since they put patients on high protein diets, which “conventional wisdom” has told us would cause kidney damage (though there is no data to support this in healthy individuals^6-11).

Results:

The great part of this study was the author’s analysis of both fat and lean weight gain, not just total weight.

All groups gained weight, however the low protein group gained 3.16 kg (2.2 pounds per kg) and the other normal/high protein groups gained 6.05 kg.  However, all groups had increased caloric intake and there was no control arm, so declaring calories as the only cause of weight gain is not accurate.

Also, these results will likely cause some to immediately declare that the low protein diet is better, which is exactly what NPR did in this article:  Calories Trump Protein for Weight Loss.  In fact, in the same issue of JAMA, other authors published the article “Overeating and Overweight: Extra Calories Increase Fat Mass While Protein Increases Lean Mass¹²”.  They forgot to add “in Individuals on High Carbohydrate Diets” to the end of the title.  Also, this is of course ignoring the several randomized studies that show that calorie restriction is not the key to weight loss, but rather carbohydrate restriction^15-18.

The Real Results:

However, upon taking a closer look, lean body mass (i.e. muscle and improved physique) decreased in the protein group by 0.7 kg (about 2 pounds) and increased in the higher protein groups by an average of 3 kg (over 6 pounds).  The overall increase in fat mass was 3.5 kg and no different between any of the groups.  Basically, everyone put on weight, with all groups gaining the same fat, but the high protein group gaining nearly three times more lean mass.  This is the real headline of the article.  Also, overeating in the higher protein groups led to a significant increase in resting energy as well as increased energy expenditure (related to amount of protein intake).  In fact, the authors concluded that the protein intake required to prevent loss of lean body mass was at least around 78 grams per day, which is higher than the suggested amount by our nutritional authorities.  Or, as stated by the authors:

“Protein intake predicted the increase in lean body mass, but not the change in fat storage.”

Looking at the results of this trial and of those randomized trials showing a benefit to low-carb diets in terms of weight loss, regardless of calories consumed, it would be of value to see a study comparing different levels of fat and protein intake with low carbohydrates.

Though the fact that eating more food likely provides one with more resting energy and energy available to exercise, this is nothing new to many of us.  Gary Taubes has been preaching his theory that increased caloric intake leads to increased resting energy and ability to exercise for years^13,14.  This is basically one reason why telling a patient to eat less and exercise more is often torture and rarely works to lose weight.

In summary:

1. Overeating with a diet heavy in carbohydrates, regardless of calories consumed or amount of protein, will lead to fat gain.
2. However, overeating with increasing amounts of protein will lead to an increase in lean body mass.
3. Overfeeding with increased amounts of protein leads to increased resting energy and increased energy expenditure.

Though, for the readers of this website, these findings are old news.

 
 
References:

1.         Bray GA, Smith SR, de Jonge L, et al. Effect of Dietary Protein Content on Weight Gain, Energy Expenditure, and Body Composition During Overeating. JAMA: The Journal of the American Medical Association. January 4, 2012 2012;307(1):47-55.

2.         Eaton SB. The ancestral human diet: what was it and should it be a paradigm for contemporary nutrition? Proc Nutr Soc. Feb 2006;65(1):1-6.

3.         Eaton SB, Eaton Iii SB. Paleolithic vs. modern diets – slected pathophysiological implications. European Journal of Nutrition. 2000;39(2):67-70.

4.         Konner M, Eaton SB. Paleolithic nutrition: twenty-five years later. Nutr Clin Pract. Dec 2010;25(6):594-602.

5.         Kuipers RS, Luxwolda MF, Dijck-Brouwer DA, et al. Estimated macronutrient and fatty acid intakes from an East African Paleolithic diet. Br J Nutr. Dec 2010;104(11):1666-1687.

6.         Blum M, Averbuch M, Wolman Y, Aviram A. Protein intake and kidney function in humans: its effect on ‘normal aging’. Archives of internal medicine. Jan 1989;149(1):211-212.

7.         Brinkworth GD, Buckley JD, Noakes M, Clifton PM. Renal function following long-term weight loss in individuals with abdominal obesity on a very-low-carbohydrate diet vs high-carbohydrate diet. J Am Diet Assoc. Apr 2010;110(4):633-638.

8.         Lentine K, Wrone EM. New insights into protein intake and progression of renal disease. Curr Opin Nephrol Hypertens. May 2004;13(3):333-336.

9.         Manninen AH. High-protein diets are not hazardous for the healthy kidneys. Nephrology Dialysis Transplantation. March 1, 2005 2005;20(3):657-658.

10.       Martin W, Armstrong L, Rodriguez N. Dietary protein intake and renal function. Nutr Metab (Lond). 2005;2(1):25.

11.       Pecoits-Filho R. Dietary protein intake and kidney disease in Western diet. Contrib Nephrol. 2007;155:102-112.

12.       Li Z, Heber D. Overeating and Overweight. JAMA: The Journal of the American Medical Association. January 4, 2012 2012;307(1):86-87.

13.       Taubes G. Good calories, bad calories : fats, carbs, and the controversial science of diet and health. New York: Anchor; 2008.

14.       Taubes G. Why we get fat and what to do about it. 1st ed. New York: Alfred A. Knopf; 2011.

15.       Samaha FF, Iqbal N, Seshadri P, et al. A low-carbohydrate as compared with a low-fat diet in severe obesity. N Engl J Med. May 22 2003;348(21):2074-2081.

16.       Brehm BJ, Seeley RJ, Daniels SR, D’Alessio DA. A randomized trial comparing a very low carbohydrate diet and a calorie-restricted low fat diet on body weight and cardiovascular risk factors in healthy women. J Clin Endocrinol Metab. Apr 2003;88(4):1617-1623.

17.       Shai I, Schwarzfuchs D, Henkin Y, et al. Weight loss with a low-carbohydrate, Mediterranean, or low-fat diet. N Engl J Med. Jul 17 2008;359(3):229-241.

18.       Foster GD, Wyatt HR, Hill JO, et al. A randomized trial of a low-carbohydrate diet for obesity. N Engl J Med. May 22 2003;348(21):2082-2090.
 
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