• Building muscle involves hard work and the right diet.bodybuilding,muscle image by yam from Fotolia.com
  
  Trying to gain only lean mass can be difficult, especially as muscle gain involves eating more than your body needs. If you don't work your exercise program correctly then you may simply gain more fat than mass. If you neglect cardio workouts or rest days, then even a healthy diet and regular weight lifting could result in fat gain.
  
  

Eat Regularly

• Eating a regular six small meals a day may actually help to increase your metabolism, thereby burning more fat and enabling you to gain lean mass. A study by the University of Nottingham concluded that a regular eating pattern would optimize carbohydrate metabolism.
  
  

Eat Protein

• Eating or drinking protein may help to increase muscle mass, a study by the Team Denmark Test Center, at Bispebjerg Hospital concluded. Those who drank only carbohydrates after exercise gained no muscle mass at all, while those who drank whey protein gained some muscle mass. Drink a healthy protein shake, and eat lean proteins with meals. But don't exclude some complex carbohydrates--your body needs them for energy..
  
  

Heavy Weight Lifting

• Lifting heavy weight slowly will increase muscle mass, but even moderate weights will increase fat-free mass according to a 1998 study in the Journal of the American Dietetic Association by Kathleen Cullinen and Marjorie Caldwell, public health nutritionists with the Rhode Island Department of Health. The study showed increased strength and fat-free mass in 20 untrained women over 12 weeks. Be careful not to lift quickly; not only could this damage your muscles but it doesn't maximize the muscles' workout. Lift slowly, actively contracting the muscle as you go.
  
  

Cardio

• Don't underestimate the importance of cardio. Just because you want to gain lean muscle mass doesn't mean you can't benefit from an hour of cardio three or four times a week. Cardio burns calories and increases your metabolism, thereby reducing fat. However, if you want mass, do no more than 90 minutes of cardio a day, as this is likely to build lean muscles rather than mass.
  
  

Rest

• You may feel tempted to lift weights all week, but rest days are just as important as workout days. During rest days your muscles repair themselves and grow, even during sleep. So keep weight training to around three days a week, and fill the days in between with cardio while your muscles repair and get stronger.