Sure, bulking up can make you look stronger and fitter, but if you don't gain weight the right way, you might end up adding more fat than muscle to your frame. And while it's natural to add a small amount of fat when you gain weight -- not all your weight gain can come from muscle -- you should take steps to minimize fat gain when you bulk. Aim for slow-but-steady results to avoid gaining too much fat, and tweak your diet and exercise program to stay lean as you gain muscle.
Stick to a Small Calorie Surplus
Slow and steady wins the race when it comes to bulking up. Treating your diet like an all-you-can-eat calorie-fest will make you gain weight, sure, but that rapid weight loss typically comes in the form of fat, not muscle. Maximize your muscle gains by aiming for a slow weight loss of about 0.5 pounds weekly, which you can achieve by eating 250 extra calories each day on top of what you need to maintain your weight. Your body can't gain muscle quickly, so aiming for a pound of weight gain a week -- or more -- will result in more fat gain. By taking it slow, a greater proportion of your weight gain will come from muscle, so you'll stay relatively lean.
Eat Plenty of Protein to Bulk Up
Focus on upping your protein intake when you're trying to bulk up. This step offers two benefits: Protein takes more energy to digest, which boosts your metabolism, and it provides amino acids, nutrients your body needs to rebuild your muscles after each workout. People looking to bulk up should double their daily protein intake, from 0.4 grams per pound of body weight to 0.8 grams. That works out to 104 grams of protein if you weigh 130 pounds, or 136 grams of protein if you weigh 170 pounds.
Opt for dairy, lean meat, eggs, fish, soy and quinoa for complete protein, protein that supplies all the amino acids needed for muscle growth. Other plant-derived foods, like nuts and beans, typically fall short in one or more amino acids, but you can still meet your daily needs by eating them with grain-based foods. For example, serve hummus with a homemade wheat pita, or top a piece of whole-grain toast with peanut butter.
Time Your Calories to Stay Lean
The timing of your meals can affect how you gain weight, according to bodybuilding coach Chris Aceto, writing for Muscle & Fitness Magazine. You'll want to get a larger meal earlier in the day, so you can burn the carbs and fat in your meal throughout the day and avoid storing them as fat. You should also plan on a larger meal after your workout to help your muscles get the amino acids they need to recover. It also supplies carbohydrates to replenish your body's glycogen stores, which leaves you feeling energized and ready for your next workout.
Exactly how big those meals should be depends on your total calorie intake. For example, if you need 2,200 calories to gain weight, you could eat a 600-calorie breakfast and a 500-calorie post-workout meal, then eat 4 smaller meals that are 250 to 300 calories each. For personalized help with planning your calorie intake, consult a registered dietitian.
Do Cardio While You Bulk
While you should primarily focus on strength training to bulk up, since, without that you won't be able to gain any significant amount of muscle, you shouldn't forego cardio entirely. They key is to do shortened cardio workouts so you're not burning too many calories or losing muscle tissue, but you're still torching some fat and maintaining your cardiovascular fitness. Schedule 20- to 30-minute cardio workouts into your routine two to three times weekly. That might mean a short stint on the rowing machine after your strength workout or an easy jog around the neighborhood on your off days.