Mutant produces one of the largest, most calorie dense weight gainers on the market! Mutant Mass comes in a huge 6.8kg (15lb) bag and contains over 1,000 calories per serving! If you need to pack on the most mass in the shortest time possible, this is for you. Check out our creatine section for other great natural supplements to pack on more muscle: Creatine Supplements. Mutant Mass (or any weight gainer) stacks well with a creatine supplement and natural test booster to make the biggest gains in muscle mass and strength as fast as possible. Are you ready to take your body to the next level?