Catabolism -- or the wasting of lean muscle tissue -- should be avoided at all costs. Not only do you get weaker and more prone to injury, your metabolism will slow, decreasing how many calories you burn at rest. Lean muscle requires energy and effort to maintain; you accomplish this with a balanced diet and heavy resistance training. You do not need to spend hours in the gym. Instead, focus on heavy, basic exercise. Ensure you get enough protein and essential fats to maintain your muscle tissue and hormone levels. Consult your doctor before beginning any new diet or exercise program.
Consume at least 20 percent of your daily caloric intake from protein, 30 percent if you are exercising daily. Cold-water fish, chicken and very lean cuts of red meat are good sources of protein. Milk provides protein, calcium and vitamin D.
Eat at least 20 percent of your calories from fat, but avoid saturated fats. Oily fish such as salmon are high in omega-3 fatty acids, which help improve muscle protein turnover and avoid catabolism. Get additional fat from olives and olive oil, nuts and seeds.
Consume fruits and vegetables to complete your diet. Fruits are high in vitamins and slow-digesting carbohydrates to provide energy. Many vegetables, particularly leafy greens such as spinach, are high in fiber and minerals.
Supplement immediately after a workout with protein and simple sugar, with your doctor's approval. Whey protein combined with dextrose or maltodextrin helps you recover from training and replace the amino acids you have broken down when weightlifting. The more quickly you replace amino acids that have been scavenged, the less muscle breakdown you experience.
Lift heavy. Train in the five-to-eight-repetitions range per set, meaning that you use enough weight that you are fatigued within this range. Use compound, or multi-joint, movements that work the large muscle groups of your body.
Train three times a week. Start each workout with a heavy lift that stresses your lower body, such as the squat or deadlift. When squatting, go as low as you can without leaning forward. When deadlifting, never round your back.
Train your upper body heavy during your workouts. Heavy bench presses and rows work your chest and back. Additional work for your shoulders and back should come from overhead pressing and rows.
Train using three to five sets per exercise. You are not training for a marathon, you are trying to build and maintain lean muscle mass. High-volume work builds endurance, not strength and muscle.
Limit your cardiovascular training. Perform cardiovascular exercise for no more than 30 minutes per session and a maximum of three sessions per week. Extensive cardiovascular exercise can promote muscle catabolism, as your body will break down muscle tissue for energy during long training sessions.