Some embodiments relate to nutritional supplements comprising rice protein isolate. Some embodiments of the nutritional supplement comprise less than about 90 mg of leucine per gram of rice protein isolate and less than about 50 mg of lysine per gram of rice protein isolate. Some embodiments pertain to methods of using the nutritional supplements described herein to achieve one or more of weight gain, weight maintenance, growth, muscle growth, muscle maintenance, decreased muscle loss, or improved exercise training results.