Conventional wisdom says you need to eat less to burn fat and eat more when training to build muscle. So, while it may seem impossible to accomplish both at once, “there are certain times when it can be done,” says Nick Shaw, founder and CEO of Renaissance Periodization in Charlotte, N.C.
If you’re new to training, switching to healthier eating habits, or getting back into a routine following an injury, it is possible to gain muscle and lose fat simultaneously; your body adapts over time to the stress caused by changes to diet and exercise. These shifts often result in weight loss and muscle gain.
When you’re a workout newbie, your body experiences stress more easily than an intermediate or advanced exerciser. “You can take advantage of being new to fitness for quite a while before having to get serious about the finer details,” says Shaw. Most people can go one to two years while achieving these newcomer results, he notes.
The fitter you are, however, the harder you have to work to trigger a stress response in your body. Once you achieve greater fitness — or your efforts begin to plateau — you’ll have to focus on either burning fat or building muscle to see results.
Power lifters and bodybuilders, for example, tend to cycle between distinct “cut” (fat-loss) and “bulk” (muscle-gain) phases. Typically these last one to three months and bodies respond with positive results aligned with the intended goal. Pursuing either goal for extended periods of time (months or even years without a break), however, creates more stress than the body can reconcile, says Shaw. At that point, you may experience slowed progress, low energy, and burnout.