If you are skinnier than your friends, you may feel the need to gain weight to catch up in size. Most teens don't have any reason to try to gain any weight. However, you may be able to naturally put on extra pounds if you focus on developing stronger muscles.
Normal Body Variations
Teens – especially guys – may expect to develop some extra muscle weight as they grow into their adult bodies. However, your genetic makeup significantly contributes to your body type. Some teens bulk up when they do strength-training exercises, but you may have a body type that will prevent you from ever looking like a muscular model. The most important tip to keep in mind is not to overextend yourself. Pair up with a certified physical trainer who can help you stay safe and healthy and reach an optimal body weight based on your individual needs.
Begin strength training by doing only body weight exercises such as sit-ups and pull-ups prior to lifting weights. Once your trainer says you're ready to progress, practice proper lifting techniques before you add weight to the machines and try basic weight lifting exercises such as lat pull-downs and bench presses. Only do three sets of eight to ten repetitions of each exercise to start with, begin with a light weight for your warmup set and then slightly increase the weight for your next two sets. You can add more weight once you are able to comfortably perform 15 repetitions in proper form. Target all major muscle groups, including your arms, shoulders, legs, back, chest and abs.
Athletic teens tend to need more protein than sedentary teens, but most teens normally have no problem taking in as much protein as they need. You're probably getting enough protein if you regularly eat foods such as eggs, dairy, peanut butter, poultry, nuts, fish and lean meats. Other nutrients you will need as you build muscle mass are carbohydrates, fat, calcium and iron. Healthy fats such as vegetable oil and carbohydrates such as whole grains, fruits and vegetables will offer you long-lasting energy. Calcium from dairy foods will help you prevent stress fractures; and iron from foods such as leafy greens and lean red meats will carry oxygen to your muscles.
Never begin a weight-training routine without warming up and never end a routine without cooling down. Warm up by getting in five to ten minutes of light aerobic activities such as jogging, and cool down your muscles by doing some gentle stretching. Give your body at least a day of recovery time between muscle building workouts by limiting your exercise to two or three sessions per week, and limit sessions to 40 minutes or less to prevent fatigue. Finally, don't neglect your heart and lungs; get in at least 20 to 30 minutes of aerobic exercise most days of the week.