Pay special attention to strength training. Athletes alternate a high-calorie program with a calorie-reduced, as during a set of muscles and inevitably some increase in fat mass. The period when she leaves, also called "drying". The body, which lacks calories to get energy, burns not only fat but also muscle if not to train them at this time.
Usually for weight loss people prefer aerobic exercises, which burn fat. But they practically do not improve the condition of muscles, so be sure to include in your complex anaerobic exercise, which have a distinct preservation effect of the muscles. So you can retain muscle mass, even if sitting on a low calorie diet.
Eat right. To body burns fat and hit muscle, you need to increase the amount of protein, which is necessary for muscle tissue. Compensate for the exclusion of carbohydrate protein food. For every pound of body weight you will need approximately 2 g protein if you are in a phase of fat burning.
If you actively train and take a day more the norm in 2G of proteins per 1 kg of the body, increase the amount of protein intake, while reducing the percentage of carbohydrates in your menu. For those who are prone to accumulation of fat, if you just reduce carbs, but not to reduce proteins, it is already possible to achieve results.
No professional athletes, people who just lose weight and don't want to lose muscle, work well those recommendations. Join a gym or a fitness club, make time for strength training. Eat more meat, dairy products, nuts, even at a low level of force activity, you will not lose muscle mass.