Boys, girls please understand that skinny people tend to have problems or complications R”L during pregnancy (or trying to get there). (THe same is for grossly overweight people. Because everyone is different please find out from your physician what your weight should be.
Boys: see above and think long term as you are considering shidduchim. This is besides for the superficiality of the matter. The “looks” are anyway gone in a short amount of time.