High-calorie supplements called mass gainer protein powders aid in the development of lean body mass. Along with protein, most bulk gainers also include carbohydrates. Some will also include a small amount of fat-related calories. A positive protein balance is what a bulk gainer protein powder aims to accomplish. This indicates that the body produces more protein than it breaks down. Research backs up the significance of regularly consuming high-quality proteins and carbs in conjunction to weight training workouts to achieve a favorable protein balance.