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,
A quick internet search using the terms "burn fat, build muscle" returns a wide array of results including special drinks, intense diet plans, and complex bodybuilding routines. They sound like miracle products, but can it be true? With so much to consider from both a nutritional and exercise standpoint, it's no wonder that you could be a little confused. As it turns out, and sorry for adding to any confusion, the short answer to your question is… "depends."
Anabolism, the process of building muscle, requires a consistent intake of calories, especially protein, plus appropriate resistance exercise to stimulate the many cells involved in muscle development and adequate rest to allow repair and growth of muscle tissue. With weight loss, the goal for many is to lose fat and keep muscle. Unfortunately, the body doesn't burn fat only when fewer calories are consumed; carbohydrates and proteins are also utilized for energy. When a person loses weight, s/he usually loses not only fat, but also water and protein. If a person is restricting carbohydrates in her/his eating plan, protein will be used for energy and won't be available for muscle repair and growth.
Here's where the "depends" comes in. If someone is new to exercise, and her/his body has a significant amount of stored fat, s/he may experience noticeable muscle gain and fat loss as s/he engages in a consistent and well-rounded (cardio and resistance training) exercise routine. This is very different than a lean individual who already has muscle mass but is suddenly motivated to pack on 20 pounds of muscle. In order to preserve lean body mass, taking in sufficient protein (up to 2 g/kg. or 0.9 g/lb of body weight) is recommended.
So, what is the answer to this quandary? Try to maintain balance and avoid extremes. While trying to lose fat, it's good to work on preserving muscle. Dieters frequently lose lean body mass and experience decreases in their metabolic rate. Engaging in both resistance and cardio training may help with maintaining strength, muscle tone, and bone health.
Losing fat and building muscle doesn't require miracles (or specific miracle products), but it does involve a smart approach to fitness and nutrition. Check out other Q&As in the Nutrition & Physical Activity archives for more ideas and tips. Good luck with your fitness goals!Alice!