Mass Gainer Powder - Serious Mass by Optimum Nutrition delivers high-calorie support for individuals looking to build muscle and gain weight effectively. With over 1,250 calories and 50 grams of protein per serving, this premium formula is ideal for those with high metabolic rates or those struggling to meet their nutritional goals through food alone. Enhance your strength and size with added vitamins, minerals, and glutamine to fuel recovery and performance.