For women aged 60 to 75 with muscle loss due to aging, consuming more protein each day for 12 weeks leads to measurable increases in thigh and calf muscle size, stronger hand and knee muscles, and reductions in body fat and waist size.

For older women with muscle loss, increasing daily protein intake from 0.8 to 1.2 grams per kilogram of body weight for 12 weeks leads to measurable improvements in handgrip strength and knee flexion strength compared to maintaining the standard intake.

In older women with muscle loss, increasing daily protein intake from 0.8 to 1.2 grams per kilogram of body weight for 12 weeks leads to a measurable decrease in fat deposits within and around the thigh and calf muscles.

In older women with muscle loss, eating more protein each day for 12 weeks leads to a larger decrease in body fat and waist size compared to eating the standard amount of protein.

For older women with muscle loss, eating more protein—1.2 grams per kilogram of body weight per day instead of 0.8 grams—over 12 weeks leads to bigger gains in muscle size and strength.

Older men with muscle loss who do strength training and take collagen supplements gain more muscle mass (4.2 kg) than those taking a placebo (2.9 kg).