Q: Dear Mike,

I am 18 years of age, and 170cm tall. I am currently underweight at 48kgs.
I would like to gain some weight, but dont want to gain fat, I want to gain lean muscle
Could you please advise me on what type, and how much exercise I should be doing?
I really also need a diet plan of what to eat.

Thank you for any help you can give me

A: You are definitely quite a bit underweight and gaining some weight and even some fat is probably a good idea health-wise. For somebody like you the main thing is to EAT A LOT!! Your metabolism is likely quite high naturally and you will not easily gain new fat or even weight. You need to provide enough food for your body to start gaining weight. There's absolutely no other way to put on weight other than to eat a lot and often.

As I said, you probably should not be afraid to put on some new fat for health reasons, especially if you are female, but it's understandable that you mostly want new muscle and there's a proven way to do that: heavy, whole-body weight training. That combined with a generous diet will result in new muscle and new weight.

So here's what you need to do:
1) Read http://www.mikesfitness.com/content/nutrition to learn what are healthy foods that you should be eating
2) Read http://www.mikesfitness.com/content/weight-training to learn how to train your whole body with weight
3) Use http://www.mikesfitness.com/content/fitnessguide to get a starter diet and weight training program.

The starter program is just that -- a starter program. It is not the ultimate prescription. Everybody is different and it is very possible that the diet prescribed by the Fitness Guide will not provide enough calories for you to gain weight. If a whole month passes and you haven't gained 1 kilogram, then you need to use what you learned reading the Nutrition article to add about 300 calories to your daily intake, mostly in the form of healthy carbs. That should be your weight gain pace -- about 1 kilogram every month. The first week you will likely gain more because of new water weight and you should ignore those first-week results. But after that weigh yourself every few mornings after using the bathroom and before eating or drinking anything. You'll find your weight will likely go up and down day-to-day, but over a long term you should see a clear uptrend. As I said, 1 kilogram per month is a great weight gain pace for somebody like you.

And don't forget to do heavy whole-body weight training as outlined in the article and the Starter program. You don't have to follow my program but whatever program you do follow has to have you lift heavy and lift with your whole body. Simply doing crunches and shoulder presses is next to useless. You need to be doing squats, lunges, deadlifts, pulldowns, rows, and bench presses.

If you want you can also do cardio such as running, but cardio works against weight and muscle gain, so if you decide to do cardio remember to eat even more to compensate for the burned calories.

Feel free to start a fitness blog here -- it's completely free and then I can monitor your progress, answer your questions, and offer advice: http://www.mikesfitness.com/content/start-your-fitness-blog . Good luck!