Is a Calorie Really a Calorie? Metabolic Advantage of Low-Carbohydrate Diets

Abstract

The first law of thermodynamics dictates that body mass remains constant when caloric intake equals caloric expenditure. It should be noted, however, that different diets lead to different biochemical pathways that are not equivalent when correctly compared through the laws of thermodynamics. It is inappropriate to assume that the only thing that counts in terms of food consumption and energy balance is the intake of dietary calories and weight storage. Well-controlled studies suggest that calorie content may not be as predictive of fat loss as is reduced carbohydrate consumption. Biologically speaking, a calorie is certainly not a calorie. The ideal weight loss diet, if it even exists, remains to be determined, but a high-carbohydrate/low-protein diet may be unsatisfactory for many obese individuals.

Keywords:

• low-carbohydrate diets
• ketogenic diets
• high-protein diets
• obesity
• energy balance
• Atkins diet
• body composition
• thermodynamics

Acknowledgements

I thank Prof. Richard Feinman (Department of Biochemistry, SUNY Downstate Medical Center, Brooklyn, NY) for helpful advice.