Can You Lose Muscle if You Don't Maintain Calories?

Building muscle mass is dependent on adequate energy intake.
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You might be at risk of losing muscle mass if you do not consume a certain amount of calories. Adequate intake of carbohydrates, protein and fat is imperative to provide energy for workouts, as well as to build lean muscle tissue. Cutting calories can help you lose weight, but some of the weight might come from losing muscle mass.

Calorie Restriction Concerns

If you do not consume enough food to maintain the calories your body needs, you might wind up with a lower amount of muscle mass. Elisa Zied, a registered dietitian and contributor to, explains that after restricting calories for 12 months, you are more likely to have less muscle mass and a diminished ability to perform exercise regimens, as compared to simply exercising more often without cutting calories. Additionally, consuming more calories from protein can result in as much as a 4 percent decrease in body weight from fat and not from muscle loss, explains the University of Illinois Extension website. Increasing your calories from protein not only helps build muscle, but also it helps keep you satisfied for a while, so you'll be less likely to snack throughout the day.

Caloric Recommendations

Having a balanced diet means that you consume just the right amount of calories you need for energy expenditure. Feeling tired and groggy during a workout means that you might not be consuming enough calories. But if the scale goes up every week, you may be consuming too much. Calorie needs vary depending on gender and activity level. Men usually need more calories than women and being highly active further increases your caloric requirements. Sedentary older women need about 1,600 calories per day, but if you are younger and routinely work out, you might need as much as 2,400 calories per day. Usually sedentary older men should get about 2,000 calories from a daily diet, which is far less than a younger active man who requires as much as 3,000 calories, according to the U.S. Department of Health and Human Services Dietary Guidelines for Americans 2010.

Macronutrient Breakdown

Not only do you need to consume a certain amount of calories to sustain muscle mass, but also you need calories from various macronutrient sources. If you're not seeing the results you want from your workout, it could be related to inadequate macronutrient intake. Your diet should consist of 45 to 65 percent carbohydrates, 10 to 35 percent protein and 20 to 35 percent fat. Carbohydrates are the main source of fuel in your body. When carbs run out, your body automatically turns to fat or protein for energy, depending on which one is available. Both carbohydrates and protein offer four calories per gram, but fat is a concentrated energy source and has nine calories per gram. As an example, based on a 2,000-calorie diet, you need 225 to 325 grams of carbs, 50 to 175 grams of protein and 44 to 77 grams of fat each day.

Cutting Calories

Because protein is the building block of muscle tissue, you should avoid cutting calories from protein if you are concerned about losing muscle. Opt for minimizing your fat intake or reducing some of your carbohydrate consumption. If weight loss is your goal, you need to cut or burn 3,500 calories from your diet each week, to result in a one-pound of weight loss, says Cutting 500 calories out of your daily diet can be difficult. Instead, reduce your caloric intake by 250 calories and burn 250 calories from exercise. Find ways to increase your physical activity throughout the day, such as parking at the furthest parking spot or walking to your boss' office in place of sending an email. At the end of the week, you'll be at a 3,500-calorie deficit and about one pound lighter.

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