Optimum Nutrition Pro Complex Gainer gives natural flavor and it contains 650 calories, 60-gram protein, 85-gram carbohydrates, 25 vitamins and minerals. All people are not same, some people require more calories while some require less calories to gain lean mass and not all calories are created equally. This ON protein based product is totally different to its competitors, other weight gaining formulas may contain lots of sugar and fat but it contains very less sugar.