No Connection between Protein and Fat

In a study conducted among 25 healthy individuals living in a controlled setting who were randomized to over-consumption of different levels of protein diets, those consuming the low-protein diet had less weight gain compared to those consuming normal and high protein diets, and calories alone, and not protein appeared to contribute to an increase in body fat, according to a study in the January 4 issue of JAMA. The researchers also found that protein did contribute to changes in energy expenditure and lean body mass.
"Obesity has become a major public health concern with more than 60 percent of adults in the United States categorized as overweight and more than 30 percent as obese," according to background information in the article. The role of diet composition in response to overeating and energy dissipation is unclear.
George A. Bray, M.D., of the Pennington Biomedical Research Center, Baton Rouge, La., and colleagues conducted a study to determine whether the level of dietary protein differentially affected body composition, weight gain, or energy expenditure under tightly controlled conditions. The randomized controlled trial included 25 U.S. healthy, weight-stable male and female volunteers, ages 18 to 35 years, with a body mass index between 19 and 30. The first participant was admitted to the inpatient metabolic unit in June 2005 and the last in October 2007. After consuming a weight-stabilizing diet for 13 to 25 days, participants were randomized to receive diets containing 5 percent of energy from protein (low protein), 15 percent (normal protein), or 25 percent (high protein), which they were overfed during the last 8 weeks of their 10- to 12-week stay in the inpatient metabolic unit. Compared with energy intake during the weight stabilization period, the protein diets provided approximately 40 percent more energy intake, which corresponds to 954 calories a day.