Too little protein may equal too much body fat
People who consistently consume more calories than they burn each day will lose lean muscle and accumulate body fat more easily if their diets contain too little protein and too much fat and carbohydrates, suggests a study published this week in the Journal of the American Medical Association.
The study included 25 people who lived in a carefully controlled research facility for up to three months, exercising very little. For two of those months, all of the men and women intentionally ate about 1,000 calories per day more than they needed to maintain their weight, but they consumed different amounts of protein.
People assigned to a low-protein diet gained roughly half as much weight during the experiment as those assigned to a standard or high-protein diet, but body fat—rather than lean body mass, which includes muscle—accounted for a much higher percentage of their weight gain.
In the low-protein group, approximately 90% of the extra daily calories were stored as body fat, but in the other groups just 50% of the added calories became fat and most of the remainder were burned off. People on the low-protein diet lost an average of 1.5 pounds of lean body mass, while those in the normal- and high-protein diets gained about 6 and 7 pounds, respectively.
The findings debunk a decades-old theory, supported by more recent research, that low- or high-protein diets can fight weight gain by tricking the body into shedding excess calories without storing them, says study author Dr. George A. Bray, M.D., chief of clinical obesity and metabolism at the Pennington Biomedical Research Center, in Baton Rouge, Louisiana.
“You don’t fool nature by adding more or less protein,” he says. “You may fool the scale, but you don’t fool the metabolic processes which store excess calories as fat.”