My niece is 10 and overweight what can I do to help?

She's eating emotionally because of her sadness. It's a dang shame her mother doesn't wish to help her. Your niece has to want to lose the weight or nothing will work. Even if the mother helped her. She is WAY too young for a boyfriend but I agree...if a boy gives her the attention that she so badly craves from her mother (and doesn't seem to get) she might hook up with him. That would be really bad. Just make yourself available for her to talk to and if your 18 year old can talk to her, that would be great.