With almost everyone I've encountered who lost a lot of weight rapidly and may have looked "too thin" for a while, it's a temporary thing, just until the body has the chance to shift fat around to different places and even everything out, which it doesn't necessarily do during the weight loss phase. Plus, it's an initial shock when you're used to seeing someone (including yourself in the mirror) look one way and now they are very different and it's jarring. I know within a year at the most after my brother had VSG and went from 300+ lbs to around 150 lbs (which was very skinny because he's 6ft tall), his appearance went from shockingly skinny to totally normal and healthy, even though his weight didn't go up during that time. Within another year after that, he'd gained several pounds and was at a weight he maintained for several years after that. It was all just part of the process.