Optimum Nutrition Serious Mass Chocolate Optimum Nutrition Serious Mass Chocolate ; the ULTIMATE in weight gain formulas. Serious Mass supplies you with the tools you need to pack on the pounds and develop the physique you've always wanted. 1250 calories per serving 250g of carbohydrates per serving 50g of protein per serving Optimum Nutrition Serious Mass Chocolate Optimum Nutrition Serious Mass Chocolate ; the ULTIMATE in weight gain formulas. Serious Mass supplies you with the tools you need to pack on the pounds and develop the physique you've always wanted. 1250 calories per serving 250g of carbohydrates per serving 50g of protein per serving