Im 4'11 and im 19. Im also 100 pounds. I used to be 135 pounds. How do i gain that weight back?
even though everyone would tell you just to eat more, gaining healthy weight actually requires some planning. You can't just simply eat (for example) burgers for breakfast, lunch and dinner and hope to remain healthy and gain weight. What you need to do is to up your protein intake, which would mean eating more red meat, or having protein shakes as a snack. Also, you can eat more carbohydrates like pasta, all kinds of bakery products or sweets, but you need to keep in mind that too much sugar isn't healthy - you need to find some balance. To help you balance out the amount of food you eat, you should also try to be active and exercise - not to burn calories, but to tone your body so that weight you gain distributes evenly,
Wish you all the best,