A new study published in the Journal of the American Medical Association makes a distinction between calories that get stored as body fat and calories that get used exercising to build lean muscle mass.  Over a 3-month period, study subjects overate and were deliberately inactive. Those who ate a low-protein (5 percent) diet did lose more weight—but they also stored more body fat and lost lean muscle mass. In fact, the low-protein group stored an astounding 90 percent of their calories as body fat, versus just 50 percent for the high-protein (25 percent) group. (Your body uses more energy building muscle than storing fat; we all know that, but the study results underline that this applies to our food choices, not just how much we exercise.)

The study’s protein takeaway

Federal recommendations for protein (46 grams for women and 56 for men daily) may not be enough to maintain muscle mass, especially as people age (and naturally lose muscle). The study participants needed to consume at least 78 grams of protein daily to avoid losing muscle, said study author Dr. George A. Bray, MD, chief of clinical obesity and metabolism at the Pennington Biomedical Research Center, in Baton Rouge, Louisiana.

Read about more new studies on protein’s key role in weight management. To learn about wise food choices and metabolism, see “The hormone balance plan.