Does extra protein prevent muscle loss?

Researchers randomly assigned 106 adults with type 2 diabetes and excess weight to eat a diet with either 20 or 40 percent of its calories from protein as part of a weight-loss program.

The high-protein group was told to eat at least 4 weekly servings of lean beef. The normal-protein group was told not to eat any red meat. (The beef industry partly funded the study and had paid speaking fees to some of its authors.)

After a year, both groups had lost roughly 25 pounds, with no differences in lost fat or lean (mostly muscle) mass or blood sugar levels.

What to do

If you’re cutting calories, cut fat or carbs, not protein. But there’s also no need to pile on the protein, especially from beef.