If you’re cutting calories, it makes sense to cut carbs and fat rather than protein. But does extra protein keep you from losing muscle as you lose weight? Researchers randomly assigned 70 middle-aged women with obesity to an RDA-protein diet that cut calories and averaged about 80 grams of protein a day, the Recommended Dietary Allowance (0.36 grams for each pound of body weight, which averaged about 215 pounds when the study started), a higher-protein diet that cut the same number of calories but had about 50 percent more protein (115 grams, on average), thanks to extra whey protein, or a control group that didn’t cut calories and had the RDA for protein.