If you're someone who lifts weights and isn't overweight, eating more protein while cutting calories helps you keep more muscle — especially if you base your protein needs on how much muscle you have, not your total weight.

What we've found so far is that higher protein intake may help preserve muscle when cutting calories in people who lift weights and are not overweight [1]. The evidence we've reviewed leans strongly in this direction, with 33.0 supporting assertions and none that refute it. Our analysis of the available research suggests that when resistance-trained individuals reduce their calorie intake, eating more protein can make a difference in how much muscle they retain [1]. This appears to be especially true when protein intake is based on how much muscle a person has, rather than their total body weight. That means two people of the same weight might need different amounts of protein if one has more muscle than the other. We don’t yet know how this might apply to people who don’t lift weights or who are overweight, because the evidence we’ve reviewed focused only on those who are resistance-trained and not overweight. Also, we’re not able to say exactly how much protein is ideal, only that higher amounts—tailored to muscle mass—seem to support muscle retention during calorie restriction. Based on what we’ve reviewed so far, the pattern is clear: more protein tends to go hand in hand with better muscle preservation in this specific group [1]. But we also recognize that new evidence could refine or expand this understanding over time. Practical takeaway: If you lift weights and are reducing calories, eating more protein—especially adjusted for your muscle mass—might help you hold on to more muscle.