Optimum Nutrition is proud to bring you Pro Complex Gainer - the worlds premier "lean gainer" supplement. Unlike typical weight gain formulas, ON Pro Complex Gainer derives a much higher percentage of its calories from protein. And, while some "ultra-hardgainers" require 1000, 1200, or even 1500 calorie/serving weight gain products, many athletes can gain quality mass with considerably less. So, in addition to calories, ON Pro Complex Gainer provides a blend of 6 premium protein sources, complex carbohydrates, dietary fiber, lipids, digestive enzymes, vitamins and minerals.