Met rx xtreme size up is a clean mass gain powder formulated to help build and maintain muscle each serving contains 687kcal 54g of protein 96g of carbs 4g of fibre 3g of creatine monohydrate and over 30 vitamins and minerals the primary carbohydrate source is oat flour and waxy maize as opposed to maltodextrinsugar in most other mass gain powders which may lead to increased fat storage perfect for anyone looking to increase their daily calorie and macronutrient intake drink through