Bottom Line: Overeating Boosts Fat, Whatever the Protein Level
But Diets High in Protein Put on Less Fat, More Lean Body Mass
Overeating & Protein Intake: Lessons
"The low-protein diet was clearly not good in terms of preserving lean body mass," Bray says.
The researchers did not find much difference in terms of body composition changes between the 15% or the 25% protein diet, Bray says.
"Based on the study, healthy adults should consider getting 12% to 15% protein [from their diet]," Bray says. (That recommendation does not apply to the elderly or athletes, he says, who may need more.)
For a 2,000-calorie diet, that level would mean taking in about 300 calories or 75 grams of protein daily. (A gram of protein has 4 calories.) A 3-ounce skinless chicken breast has about 27 grams of protein. Six ounces of Greek yogurt has about 14 grams.
Bray serves as a consultant for Abbott Laboratories and Takeda Global Research Institute. He is an advisor to Medifast, Herbalife, and Global Direction in Medicine. He has received royalties for the Handbook of Obesity.
Overeating, Protein, & Weight Gain: 'The Danger of Eating Low Protein'
The study results suggest the downsides of eating too little protein, says David Heber, MD, professor of medicine at the UCLA David Geffen School of Medicine and founding director of UCLA's Center for Human Nutrition. He co-authored an editorial to accompany the study.
"The danger of eating low protein is you eat too many refined carbohydrates," he tells WebMD. White bread, for instance, is a refined carbohydrate. "That puts on weight. And that weight tends to be fat."
"Protein is a great thing to control your appetite and to maintain lean body mass," Heber says. "I have been a proponent of increasing protein without increasing fat. Right now, most Americans are at the lower end of protein intake [recommendations]. You have to have protein to maintain lean body mass."
Heber reports serving as counselor for the Obesity Society. He is an advisor for POM Wonderful, Herbalife, and McCormick Spices. He has received book royalties for What Color Is Your Diet? and The L.A. Shape Diet.