Serious weight gain goals require serious calories. Unfortunately, those who need the extra calories most often have a hard time consuming enough of them. For many aspiring to be bigger, a highly- active metabolism, weaker appetite and on-the-run lifestyle can make it a real challenge to get enough calories from food. With 1,250 calories and 50 grams of protein per serving, you've got lots to gain from ON's Serious Mass. Get serious about your sizable ambitions with Serious Mass.