Dietary Protein Affects Energy Expenditure, Not Body Fat
Low-protein diet group has less weight gain, no increase in energy expenditure, body protein
TUESDAY, Jan. 3 (HealthDay News) -- For individuals in a controlled setting, the protein content of a diet affects energy expenditure and storage of lean mass, but does not impact body fat storage, according to a study published in the Jan. 4 issue of the Journal of the American Medical Association.
George A. Bray, M.D., from Pennington Biomedical Research Center in Baton Rouge, La., and colleagues investigated the effect of overconsumption of low-, normal-, and high-protein diets on weight gain, energy expenditure, and body composition among 25 healthy, weight-stable males and females. Participants consumed a weight-stabilizing diet for 13 to 25 days, and were then randomly allocated to be overfed for eight weeks, with diets containing 5, 15, or 25 percent of energy from protein (low-, normal-, and high-protein groups, respectively). Body composition, and resting and total energy expenditures were measured.
The investigators found that, in the low-protein group, overeating resulted in significantly less weight gain than in the normal- or high-protein groups (3.16 versus 6.05 and 6.51 kg, respectively). In all three diet groups, there was a similar increase in body fat, which represented 50 to more than 90 percent of the excess stored calories. In the low-protein diet group, resting and total energy expenditures and body protein did not increase. In the normal- and high-protein diet groups, there was a significant increase in resting energy expenditure (160 and 227 kcal per day, respectively) and in body protein (2.87 and 3.18 kg, respectively).
"Protein contributed to the changes in energy expenditure and lean body mass, but not to the increase in body fat," the authors write.
One author disclosed ties to the pharmaceutical and weight-loss industries. Another author disclosed financial ties to the pharmaceutical and health care industries.