As much as I worry about those getting too heavy (I don't care about that "looks" thing people talk about because everyone looks the same to me), I would worry if someone crash dieted without a real lifestyle change. Sure, I might feel envious because I need to lose a little, but also it is a real concern. They might take it too far, they might not have found healthy routines and suddenly swing to overeating. If they crash diet, how do they know when to stop and what stop means? Do they know a healthy way to maintain weight or do they just have the tools to lose or gain? That is what I wonder.