Although you can make muscle gains on a calorie deficit, depending on the specifics of your situation, that may not be the ideal approach. Bodybuilders often do better with alternating bulk and shred cycles before a competition.
But if general weight loss is your goal, the idea of maintaining lean muscle mass while on a calorie deficit — or perhaps even building a bit of muscle — is more realistic and easier to maintain.
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If you combine the right exercise stimulus with appropriate nutrition, it is possible to build some muscle on a calorie deficit — although your first priority should be preserving the lean muscle mass you already have.
How Your Body Builds Muscle
For your muscles to undergo hypertrophy — another way of saying they get bigger — two conditions absolutely must be met. The first is the appropriate stimulus for muscular hypertrophy. As explained by the American Council on Exercise, that can be:
- mechanical (but minor) damage from a challenging lifting session,
- time spent under tension for your muscles, or
- metabolic fatigue — working your muscles to the point that they briefly run out of the fuel they need to contract.
The second factor your body needs to build muscle is adequate rest between training sessions. It's understandable to imagine that your muscles get stronger while you're lifting, but in truth they get stronger during the rest and recovery period between workouts. That's why experts recommend taking at least one full rest day between strength-training workouts for a given muscle group — and sometimes more if the workout was really intense.
There is a third factor at play: Your nutrient and calorie intake. As the International Sports Sciences Association explains, the ideal conditions for muscular hypertrophy involve a small calorie surplus, which frees up the nutrients and energy for your body to restructure your muscles to be bigger and stronger than they used to be.
Gains on a Calorie Deficit
That doesn't mean you can't build muscle, and stay healthy, while on a caloric deficit. But you should restrict your deficit to the healthy 500 to 750 calories fewer per day recommended by the National Heart, Lung and Blood Institute. If you keep that up over time, it'll lead to a weight loss of 1 to 1.5 pounds per week.
You can push it a little more — the Centers for Disease Control and Prevention describe a healthy rate of weight loss as 1 to 2 pounds per week — but taking the weight loss faster than that reduces your potential for gaining muscle and also endangers your long-term weight loss, because weight that you lose through unsustainable "crash diet" methods often comes back with a vengeance.
The best fat-burning, muscle-building diet is rich in nutrients, including lots of whole grains and brightly colored fruits and vegetables, as recommended by the Department of Health and Human Services. But it also needs to be particularly rich in high-quality protein. The International Society of Sports Nutrition recommends that if you're on a hypocaloric diet, you should consume 2.3 to 3.1 grams of protein per kilogram of body weight to maintain and build lean muscle mass.
Keep in mind that even though you can build muscle on a calorie deficit, you're not really creating the ideal circumstances for muscular hypertrophy; so your gains won't be as impressive as they would be without the calorie deficit. That's why bodybuilders typically focus on either bulking (building muscle) or shredding (cutting fat), instead of doing both at once.
The Benefits You Could Gain
However, if you're on a mission to shed excess body fat and build muscle for the health benefits both achievements offer, then it's realistic to aim for gradual fat loss and building modest amounts of lean muscle mass at the same time. In fact, if you've never challenged your muscles before, you might find that they respond more quickly than you expected.
As explained by Len Kravitz, PhD, an exercise researcher with the the University of New Mexico, those first gains are usually thanks to neural adaptation. But after around 16 workouts — for most exercisers, that's about twice a week over two months — you can start to see real muscle growth too.
Speaking of health benefits from weight loss, you don't have to lose drastic amounts for those benefits to kick in. As the Obesity Action Coalition explains, even a modest 5 to 10 percent weight loss confers benefits like healthier levels of cholesterol and blood pressure, reduced inflammation, better management (and lower risk) of diabetes and even better sleep quality.
And when it comes to building muscle, there's no denying that strong is the new skinny — or to put it another way, a certain amount of sleek muscle has become a mainstay of popular beauty norms. But that's not the only benefit you get from hitting the weights. Regular weight training also helps you build stronger bones, makes everyday tasks easier, speeds your weight loss efforts along and can help manage some chronic conditions.
How You Should Lift
Remember that regardless of whether you're operating with a calorie deficit, lean muscle mass only increases when given the appropriate stimulus. If you're just starting out, lifting full water bottles or soup cans might be a challenge — but that won't be the case for long. And if you stop challenging your muscles, they won't have any reason to develop further.
That's why your fitness program should always progress as you do. That doesn't mean jumping from 50 pounds to 350 on the bench press — that kind of drastic advancement is a good way to get hurt. Instead, set a realistic goal for sets and repetitions; a good place to start is the Department of Health and Human Services physical activity guidelines for Americans, which recommend doing one to three sets of eight to 12 repetitions for each strength training exercise you choose.
Ideally, completing that last repetition with good form should be doable — but a real challenge. Once that's no longer a challenge, it's time to slightly increase the amount of weight you're lifting, or consider choosing a more difficult variation of that exercise.
Finally, doing multi-joint exercises — also called compound exercises — is the most time-efficient way of training, because it works multiple muscle groups at once. Working more muscle also translates to burning more calories, and compound exercises tend to more closely mimic (and prepare you for) real-world motions than isolation exercises that work only one muscle group at a time.
Once you've established that, the type of strength-training you do isn't particularly important as long as you're appropriately challenging all your major muscle groups. Bodybuilders and power-lifters may pursue specialized lifting programs, but if you're lifting for general health you can get excellent results from body-weight training, free weights, weight machines, strength-training in boot camp classes and so on.
The most important thing is to get out and move, challenge your muscles, and make sure your body has the appropriate nutrients and stimuli needed to keep that lean muscle mass growing.
- Centers for Disease Control and Prevention: "Losing Weight"
- Mayo Clinic: "Strength Training: Get Stronger, Leaner, Healthier"
- Health.gov: "Physical Activity Guidelines for Americans"
- Obesity Action Coalition: "Benefits of 5-10 Percent Weight Loss"
- University of New Mexico: "Resistance Training: Adaptations and Health Implications"
- Journal of the International Society of Sports Nutrition: "International Society of Sports Nutrition Position Stand: Diets and Body Composition"
- American Council on Exercise: "The Do's and Don'ts of Building Muscle"
- International Sports Sciences Association: "Building Muscle Simplified: Not as Complicated as You Think"
- Health.gov: "Key Elements of Healthy Eating Patterns"