Protein before or after training promotes muscle mass and strength. Weight training causes protein breakdown following exercise. Consuming protein supplements shortly before or after training prevents this and promotes muscle growth. People lose muscle mass and gain fat as they age. Weight training plus protein supplements (10 to 40 grams consumed less than one hour before or after weight training) improves protein balance. Combining weight training and protein supplements increases strength and muscle mass and decreases fat accumulation in men and women of all ages.