I m 20 yrs and my weight is 50kg but my tummy is so fat and I want to increase my weight now what?

You can use the body wraps because it can target one area of your body such as the stomach area. It can tighten, tone and firm your sagging skin there. A sagging and slackening skin in the belly area is often mistaken as fat, that's why even if you are skinny, you get a belly. You can get a body wrap from iwbodywraps.com. It has nothing to do with your weight because it simply eliminates a few inches in your target area.