Bodybuilding builds muscle, ironically, by breaking it down. Your body responds to this breakdown of muscle by building bigger, stronger muscles. Most people can build no more than 1 lb. of muscle per week. To reach this, you must work out intensely and regularly, and you must supply your body with proper nutrition, especially protein.
Join a gym. While it is possible to work out at home, a gym offers instruction and assistance from floor attendants, as well as a social atmosphere that can help keep your spirits up when training becomes difficult.
Add 500 calories a day to your diet, including 0.4 grams of protein for every pound of body weight, advises CNN diet and fitness expert Melina Jampolis. Because a pound requires 3,500 calories to build, a 500 calorie increase a day will support a weight increase of 1 lb. per week. If your body cannot build muscle this quickly, however, some of this weight gain will be fat.
Select 8 to 10 bodybuilding exercises that work out all of your body's primary muscle groups -- arms, chest, shoulders, back, stomach and legs. Squats, deadlifts and bench presses are popular exercises that exercise primary muscle groups.
Find your "one-rep maximum" for each exercise -- the weight at which you can complete only one repetition in good form. Assign yourself a workout weight of 65 to 85 percent of your one-rep maximum. You should be able to complete at least five repetitions at this weight, and gradually add reps as your muscles grow.
Perform two to three sets of each exercise, two or three days a week on nonconsecutive days. When performing your last set of each exercise, keep lifting until you cannot complete the last repetition. Have a spotter ready to help you lift the final rep for exercises in which you can be trapped under weight, such as the bench press.
Record these details of your workout in a training log: the names of your exercises, the weights used, the number of repetitions completed, the number of sets completed and the date of the workout.
Increase your weight by 5 to 10 percent when you can easily complete 12 repetitions of a particular exercise.
Listen to your body and moderate your workouts if you feel constantly sore. Over-training can result in a loss of strength and muscle mass.