I'm 5'1 and 90 pounds. For my age (I'm 13 years old), I'm underweight. Some of you may be like don't worry about this, you're so young but I still will worry about it. For those of you who say "eat more" it doesn't work that well for me, I have a small appetite. In 3 weeks I only gained around 1 pound which really concerns me. I wanna get in shape, to gain more muscle.

  • Have you hit your growth spurt yet? If not, you may simply not have hit your stride. I was about your weight, and a bit taller, at your age. By 9th grade, I was up to my full adult height of 5'9" and had gained a good 30-40 pounds. I know, you said not to dismiss your concerns, but it just might not be time for you yet.
    – Sean Duggan
    Jan 17, 2016 at 16:16

2 Answers 2


Gaining weight as an underweight person (and I know this from experience) is having the balls to eat even though you're not hungry. This does not mean binging, but rather eating healthy food 5-6 times per day, in moderate portions.

But you can help yourself get a bigger appetite by joining a sport. I wouldn't recommend weightlifting just yet, but a form of martial arts or gymnastics is one of the best choices you could possibly make right now. It will make sure that as you grow, you grow in the right ways. It will make you both look good, and feel good.

Obviously, I'm not discounting other sports, and you should go for whatever sport you really want to partake in. Martial arts or gymnastics are suggestions that I know will give you a strong and lean body whether you want one or not.


You do not necessarily need to eat more, but you have to get correct nutrition:

  • Six smaller meals a day containing 20-25g protein each time (this is much harder to plan than you think - use a kitchen scale and nutrition tables to check the amount of protein)
  • Healthy food: Fresh fruit rather than dried or canned fruit. Raw or slightly cooked vegetables. No fast food.
  • Slow carbohydrates: Prefer whole grain products and avoid sugar.

Choose some sports, which makes you feel happy and that you have fun. Good feeling is usual the best motivation for using your body and gain muscles mass.

  • I would actually discourage eating too much raw vegetables if he wants to gain mass. Cooking releases more calories in the food. The reason why the "raw food" diet works so well in losing weight is that the body can digest so little of it. Overstewing can leech out vitamins and minerals, but no cooking reduces bioavailability.
    – Sean Duggan
    Jan 17, 2016 at 16:18
  • I agree. In many cases, the overall nutrition value of slightly cooked vegetables is better than in raw ones. Just think of cooked carrots, which gives you five times the amount of beta-carotene compared to raw ones. My point was to avoid fried and industrial processed vegetables. Strange stuff in fast-food burgers does not count. I need to gain weight too, and I have chosen to get about 50% cooked and 50% raw.
    – Gyrfalcon
    Jan 17, 2016 at 16:54

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