Not everyone has great eating habits and depending on age (if you are an adolescent) everyone goes through a chubby stage. You should really focus on yourself and not everyone around you as well. You are not the one who has to live with clothes not fitting you right and people who are overweight
are very aware of what they look like. Don't be so judgemental. Also, there are girls that are way too skinny. They look emaciated and look like they need to eat a sandwich. Don't be so focused on it and be healthy and eat right. Judgement of others can foster a poor self image.