When it comes to eating for mass gain, the most important factor is calorie consumption. To build muscle, you have to create a calorie surplus—eating more calories than your body burns through daily activities, workouts, and normal physiological processes. A solid way to determine how many calories you need is to multiply your body weight in pounds by 20. So, a 180-pound male needs about 3,600 calories on workout days to build muscle. On rest days, you’ll scale back, but nixing a pre- and post-workout meal will put you right where you need to be.
Focus on getting the right balance of protein, carbs, and fats. To calculate your protein needs, multiply your body weight by 1.5. The 180-pound guy should shoot for 270 grams of protein. Next, be sure to get ample amounts of carbs; the focus should be on low-glycemic or slow-digesting carbs like most fruits, whole grains, and sweet potatoes. Aim for at least twice your body weight in grams of carbs on workout days. The 180-pounder would need at least 360 grams of carbs per day, for example.
You’ll also need to consume adequate fat each day. Research shows that athletes who consume higher amounts of saturated and monounsaturated fat have higher levels of testosterone—the most critical hormone for instigating muscle growth. To get in enough fat, shoot for about half your body weight in grams of fat per day, or about 90 grams for the 180-pound man.