Best 3 Full Body Workouts For Size. There are a number of ways you can set up a full-body workout that's aimed at gaining size. Find out which of the following 3 options will help you. If you're looking to pack on some serious mass, one of the best ways to go about accomplishing this mission is to get on a full body workout program. Many seeking muscle gain are quick to assume that three days in the gym is not enough to effectively add body mass, however that's not the case at all. Good Luck. ".