Optimum Nutrition (ON) Serious Mass Weight Gainer Protein Powder is the ultimate in weight gain formulas. With 1,250 calories per serving and 50 grams of protein for muscle recovery support, this instantized powder makes the ideal post-workout and between meals shake for sizing up your goals. Serious Mass provides you with the tools you need to pack on the pounds and help you develop the physique you’ve always wanted.


  • Protein supplement powder with a weight gainer formula
  • Contains 23 minerals and vitamins, and high calorie content
  • Each serving includes 1,250 calories and 50 grams of protein
  • Helps in supporting weight gain and faster muscle recovery
  • Instantized powder with creatine, glutamine, glutamic acid
  • Can be used post-workout, between meals and before sleep
  • GMP approved

Additional information


12 Lbs, 6.6 Lbs