Caveman Doctor recently wrote a letter to the editor of the Journal of the American Medical Association (JAMA) regarding a recently published article on protein consumption, total calories, and weight gain. Caveman Doctor originally wrote an article on his website (here) discussing the issues, and due to the popularity of the article, he decided to directly address the editor of JAMA with a letter for publication he wrote along with several physicians at his hospital (one is a fellow caveman – actually cavewoman!). Caveman Doctor got rejected. However, Caveman Doctor’s feeling are not hurt (caveman don’t have feelings) and he decided instead to publish it on the next best source, his web site. Enjoy!

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

To the Editor:
 
Bray et al. should be commended for their work in this important study¹. Diet and nutrition are pertinent topics in all fields of medicine because of their significant influences on chronic diseases, including cancer. However, only limited conclusions can be drawn from the study. Increased calories were noted to be more significant than amount of protein consumption in all patients when determining the reason for increased body fat². Due to the study design, further experimentation would be needed to conclusively make that claim.
 
To date, randomized studies have shown that when calories are kept constant with carbohydrate content decreased, weight loss will still occur³. Therefore, metabolic influences, including insulin secretion, likely play a large role in the energy balance needed for loss of body fat. In the present study, patients were maintained on a relatively high carbohydrate diet which would likely cause frequent insulin spikes, leaving them in a state conducive to storing/gaining fat and at a disadvantage for weight loss. The carbohydrate consumption should be at least mentioned as a potential reason as to why patients gained weight. It is unknown if increasing calories, fat, and protein, but lowering carbohydrates results in weight gain. Perhaps increasing calories only in the face of high-carbohydrates causes weight gain? We have still not established whether calories alone are an independent variable or rather dependent on carbohydrate, fat, and protein intake.
 
The excellent work to separate lean and fat changes in body mass as well as to assess energy expenditure adds a great deal of knowledge to this field. The authors found a significant increase in resting energy and energy expenditure occurring when protein consumption is increased in the face of higher caloric consumption. This may shed light into why dieting strategies that include recommendations to eat fewer calories, while increasing activity are not well tolerated4. As has been suggested before, the two may work counter to each other, with a negative caloric balance potentially leading to both negative resting energy and energy expenditure⁵.
 
In light of the results of low-carbohydrate randomized trials, coupled with results in this study revealing an increase in resting energy and energy expenditure, perhaps an increase in non-carbohydrate calories would allow patients to lose weight and increase activity levels. Further trials are warranted studying the effects of caloric manipulation in the face of high-protein and low-carbohydrate diets to determine the optimal way to promote weight loss.
 
 

Reference:

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. Li Z, Heber D. Overeating and Overweight. JAMA: The Journal of the American Medical Association. January 4, 2012 2012;307(1):86-87.
3. Hite AH, Berkowitz VG, Berkowitz K. Low-carbohydrate diet review: shifting the paradigm. Nutr Clin Pract. Jun 2011;26(3):300-308.
4. Bautista-Castano I, Molina-Cabrillana J, Montoya-Alonso JA, Serra-Majem L. Variables predictive of adherence to diet and physical activity recommendations in the treatment of obesity and overweight, in a group of Spanish subjects. Int J Obes Relat Metab Disord. 2004;28(5):697-705.
5. Heymsfield SB, Harp JB, Reitman ML, et al. Why do obese patients not lose more weight when treated with low-calorie diets? A mechanistic perspective. Am J Clin Nutr. February 1, 2007 2007;85(2):346-354.
 
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