Do I Need a Certain Body Fat Percentage to Build Lean Muscle Mass?

Building lean muscle mass not only improves your appearance, but it also boosts your metabolism, promotes bone health and supports your posture. On the other hand, a high body fat percentage puts you at a higher risk of obesity-related illnesses, whether you're actually overweight or not. You don't need to hit a certain body fat percentage to start working on building muscle mass, but your body fat levels will significantly affect the visible results of adding lean mass. The strategy you should take to get to your goal physique depends on how much muscle you need to gain, as well as how much fat you need to lose to look toned.

You can start getting fit at any body fat level, but you'll need a low body fat percentage for visible muscle definition. (Image: Asysoev87/iStock/Getty Images)

The Effect of Body Fat

How much fat you're carrying has a profound effect on how you look. Excess fat forms a layer over your muscles to erase definition and prevent you from achieving that "toned," muscular look. A body fat level above 20 percent for men and above 30 percent for women will mean you have a soft appearance, even if you have a lot of muscle mass underneath the fat. As you get leaner, your muscles will become more visible. You'll generally start to look fit at 10 to 12 percent body fat, for men, and at 20 to 22 percent body fat for women. A very lean physique requires an even lower body fat level -- 6 to 9 percent for men and 16 to 19 percent for women.

While you can start building muscle tissue right away, the specific strategy you should choose depends on your current body fat levels. If you're currently very thin and want to gain overall weight as muscle mass, you'll need to employ different tactics than if you're overweight or obese and want to lose weight and retain muscle to achieve a lower weight and body fat percentage.

Calorie Counting to Look Lean

Building lean mass requires a two-pronged strategy: working out enough to stimulate new muscle growth and a diet that provides nutritional support for building lean muscle tissue.

If your initial goal involves building up more muscle tissue and gaining weight in general, you'll want to eat a slight calorie surplus each day. Take the number of calories you need to maintain your weight -- an online calculator can help you figure this out, based on your age, gender, height and weight -- and add 250 to gain a half-pound each week. For example, a 32-year-old man who is 6 foot, 3 inches tall, weighs 190 pounds, and is active about an hour a day needs about 3,350 calories to maintain weight. To bulk up, he should eat 3,600 calories daily.

If you're significantly overweight, however, you might choose to focus on losing body fat first. Carrying excess weight already increases your level of muscle mass, and starting an exercise routine will trigger further muscle growth. Therefor, you might find that you don't actually need to gain a lot of lean mass; you'll already have the muscle tissue you need to look and feel fit once you reach your goal. You can lose weight by taking 500 to 1,000 calories off your daily intake. If that 32-year-old man weighed 250 pounds, for example, he would need 3,900 calories to maintain his weight. He could cut his calories to 2,900 daily and lose about 2 pounds each week.

Diet and Exercise to Retain Lean Muscle Mass

No matter what your starting point, your diet and exercise program will need to support muscle growth and prevent fat gain. Make strength training a regular part of your routine, and plan for two or three weight training workouts weekly. Weight training slightly damages your muscle fibers; this signals to your body that your muscles need to be stronger and bigger, so your body repairs the damage and adds new muscle fibers after each workout. Do large compound exercises, like lunges and bench presses, using weights that feel very challenging after 8 to 12 repetitions. You'll know it's time to up the weight when you can perform 12 repetitions without muscle fatigue. Early in your fitness journey, you might find yourself upping the weight with each workout. However, as you continue to progress, your gains might come slower, which is normal and doesn't mean your program isn't working.

Support muscle building with a balanced diet that supplies high-quality protein, fats and carbohydrates. Your muscles use fat and carbohydrates as fuel, so these nutrients can help you feel energized when you exercise. Protein contains amino acids, which your body uses to build muscle. Calculate your protein needs by multiplying your weight by 0.55 to 0.82 calories, which, for a 170-pound person, is 94 to 139 grams of protein daily. Get your protein intake from eggs, nuts and seeds, dairy, beans and lentils, poultry, soy and fish. Eat fruits, whole grains and veggies for healthy carbs, and eat fatty fish, avocado and nuts for nourishing fat.

The basics of your diet will stay the same, whether you're looking to gain or lose weight overall. But the amount of food you eat will vary, depending on your target calorie intake.

Working Out to Lose Body Fat

You'll also need cardio to help burn fat so you can get that lean appearance when you reach your goal weight. How much cardio you need, though, depends on your starting physique and overall goals.

If you're thin and looking to gain weight and muscle, you don't need to spend hours on cardiovascular exercise. Just two or three cardio workouts a week, where you exercise at a moderate intensity for 20 to 30 minutes, is likely enough to keep you looking lean as you work to bulk up.

If you're at a high body fat level because you're overweight, though, you'll need more cardio. Aerobic exercise will let you burn more of the fat lying overtop your muscle mass, so shedding that fat will help you look fitter. Start with 150 minutes of moderate-intensity exercise weekly -- the amount recommended for weight maintenance -- and gradually increase the length of your cardio workouts as you develop more stamina. As your fitness level increases, challenge yourself to higher-intensity workouts, which burn more calories per session than moderate-intensity work and also burn more fat.

The Bottom Line -- Planning Your Strategy

Consider consulting a professional for personalized help. A professional can use accurate measurements to figure out your body fat percentage levels so you know your starting point -- and can accurately track your progress -- and analyze your physique to help you set realistic goals. Some people have an easier time putting on muscle than others; if you're a "hard gainer" who resists adding lean mass, you might need personalized help to get the results you want. On the other hand, if you're overweight or obese, a professional can help you plan a nutrition plan and exercise program that suits your current fitness level, as well as offer modifications to accelerate your results on your weight loss journey.