Being too thin or too fat can lead to some very serious health related problems.
In either case strengths training and bodybuilding combined with a proper diet could be the answer.
If you combine strength training with cardio exercises, your body will become healthy and resistant to many diseases.
Your bone structure will improve and the risk of bone loss in the early years will decrease.
Let us take a look at what you can do to gain muscle, without gaining fat.
Increase your calories The first thing you should do is to increase the amount of calories you eat.
However, be sure that these calories do not come from sugar, white bread or animal fat, since this kind of calories cause weight gain that comes with lots of health issues.
To find out how many calories you need, start to write everything you eat now, down on a piece of paper.
Do this for a week.
Then, increase your calorie intake with about 300-500 calories and see what happens.
Do this until you are satisfied with your weight gain.
Try to eat 6-8 smaller meals instead of three large ones.
This will help your metabolism.
Make sure the following is in your diet, fruits and vegetables, nuts, lean meat, poultry and fish.
You want to increase your calorie intake with healthy foods, and avoid foods with a high amount of fats and sugar.
Training To build muscle mass you need a weight lifting routine.
If you are not already training regularly in a gym, begin now.
Weight training is the best way to gain muscle mass and will benefit you no matter if you are too thin or too fat.
If it is impossible for you to join a gym, buy a set of dumbbells and start working out at home.
If you do not have workout program, I highly suggest you go invest in one.
The investment is small, compared to the knowledge and the health benefits you will receive.
I personally prefer e-books as I can use the search function to find the information I am looking for, fast.
Supplements The use of supplements is a highly discussed area in the weight-training world.
If you live on a healthy diet you should not need them.
However, in some cases supplements are necessary.
If you are vegetarian or for some other reason does not get enough protein, protein powder could be a good idea.
Again, I would recommend that you get hold of a good workout guide, which most often includes a proper diet and more information on supplements.