Boston The first phase of a caloric restriction study in human subjects at the Jean Mayer US Department of Agriculture Human Nutrition Research Center on Aging (USDA HNRCA) at Tufts University found evidence suggesting that calorie-restricted diets differing substantially in glycemic load can result in comparable long-term weight loss. The study, part of the multi-center Comprehensive Assessment of Long-term Effects of Restricting Intake of Energy (CALERIE) trial, funded by the National Institute on Aging, accounted for dietary factors that affect hunger and satiety, used laboratory techniques to measure adherence, and was the first of its kind to provide a complete set of meals and snacks to its participants. Recruitment is currently underway for participation in the second phase of the CALERIE study at Tufts, which will examine the relationship between calorie-restricted diets, aging, and age-related disease.
"Participants in our pilot study achieved and maintained comparable weight loss after one year, regardless of whether they were on a low-glycemic-load or a high-glycemic-load diet," says corresponding author Susan Roberts, PhD, director of the USDA HNRCA's Energy Metabolism Laboratory. "The goal was for both groups to restrict calories by 30 percent and, after one year, both groups had lost an average of 8 percent of their original body weight. We found that the two groups did not differ significantly in their average body fat loss, energy intake, metabolic rate, or reports of hunger and satiety."
The two study diets were carefully matched for factors known to influence food intake during weight-loss efforts, such as palatability, dietary variety, and fiber. "Because there was careful attention to factors that influence hunger and satiety, participants were generally satisfied on a calorie-restricted diet," says Roberts, who is also a professor at the Friedman School of Nutrition Science and Policy at Tufts.