The Journal of the International Society of Sports Nutrition (ISSN) takes that recommendation a step further and says active people looking to build or maintain muscle should eat 1.4 to 2.0 grams of protein per kilogram of body weight2. If you’re keeping score, that would be 105 to 150 grams of protein per day for a person weighing 165 pounds.
Resistance-trained individuals eating in a calorie deficit may need even higher protein intakes (2.3 to 3.1 g/kg/d) to minimize muscle loss during weight loss.
All that is to say, protein intake is individual and depends on several factors, including your age, weight, activity level, and goals. Your protein requirements will also change throughout your life. For example, women might need to adjust their protein intake during pregnancy and lactation to keep up with their body’s needs. People over 65 may also need to increase their protein intake since the body uses protein less efficiently as we age3.
So what happens if you don’t eat enough protein? Larson says you may experience symptoms like “a slow-healing injury, getting sick frequently, feeling more fatigued than normal, losing muscle mass, or seeing problems with your hair, nails, and skin.”
