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Cardiovascular/aerobic exercise
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Losing fat and building muscle mass: Can this be done simultaneously?
Originally Published: June 13, 2003
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Dear Alice, A friend of mine and I were disagreeing about this point and I thought maybe you could help. I have heard that it is not possible to both lose fat and build muscle mass simultaneously: ideally, a person should do cardiovascular exercise with dieting to lose extra body fat, and then start to focus on building up muscle mass. He says it's possible to both burn fat and build up muscle over the same period of time. Which is the case? —Working up a sweat
Dear Working up a sweat, As far as humans are concerned, we can't build muscle and lose fat at the same time. Anabolism, the process of building muscle, requires more calories taken in than expended, plus appropriate resistance exercise to stimulate the many cells involved in muscle development, and adequate rest to allow repair and growth of muscle tissue. Muscle tissue is comprised of 15 - 20 percent protein, 70 - 75 percent water, and glycogen (carbohydrate), fat, vitamins, and minerals in the remainder. Because of the work involved, rest required, and calorie intake needed, it's unlikely for a person to be able to gain more than two pounds of muscle in a week. As a person adds muscle, her/his metabolic rate increases slightly. With weight loss, the goal for many is to lose fat and keep muscle. The body does not burn fat only when fewer calories are consumed; carbohydrate and protein are also utilized for energy. When a person loses weight, s/he usually loses not only fat, but also water and protein. If one is restricting carbohydrate in his/her eating plan, protein will be used for energy and will not be available for muscle repair. If a person is taking in too little protein, s/he will not have an adequate amount available to fulfill its many functions, including muscle and tissue repair, enzyme and hormone production, fluid balance, and red blood cell production, among others. Weight loss involves fewer calories taken in than expended, so in this deprivation mode, one would not have the excess calories required to build muscle. As a matter of fact, low calorie eating plans can result in protein deficiency and loss of muscle tissue. So, what is the answer to this quandary? While trying to lose fat, it's important to work on preserving muscle. Dieters frequently lose lean body mass and experience decreases in basal metabolic rate. Stopping or excluding resistance exercise does nothing for maintaining strength, muscle tone, and bone health. Keeping lean body mass by weight training will also help to keep one's metabolism up. In order to preserve lean body mass, taking in sufficient protein (2 g/kg. or 0.9 g/lb of body weight) is recommended. Timing of protein intake may play a significant role in its use to repair muscle tissue — within two hours of a workout can help assure its availability. The amount of protein will depend on the intensity of the workout and a person's energy needs. Including protein, along with carbohydrate, post-exercise seems to be optimal in muscle repair. To settle the score — neither of you is exactly right. A combination of aerobic and resistance exercise, while trying to lose body fat, is recommended. Despite all the ads, tapes, and classes for "body sculpting," our bodies aren't lumps of clay, ready to be molded into a preconceived form.
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