The product you are asking about is the Optimum Nutrition (ON) Serious Mass weight-gaining powder, a highly popular and well-known supplement in the sports nutrition industry.The 1KG jar is the smallest size available, typically offering 3 to 8 servings depending on the scoop size and regional formulation.Serious Mass is specifically designed for "hardgainers"—people who have a high metabolism or struggle to consume enough whole food calories to put on weight and muscle mass.?️ Serious Mass Key Nutritional Profile (Per Full Serving)The formula is a calorie, protein, and carbohydrate powerhouse, designed to maximize muscle and weight gain.Macronutrient/IngredientTypical Amount (2-scoop serving in water)Key FunctionCalories1,250 KCAL (Increases to $\approx$ 1,640 KCAL when mixed with low-fat milk)Creates the necessary calorie surplus for weight gain.Protein50 Grams (Blend of fast and slow-digesting proteins like Whey, Casein, and Egg)Supports muscle recovery and growth.Carbohydrates250+ Grams (Primarily Maltodextrin, with No Added Sugar in many formulas)Replenishes muscle glycogen stores and provides the high calorie count.