Eating before you sleep is generally not a good idea if you're trying to diet. Your metabolism slows down when you sleep. This being said, the food you eat before bed is not being quickly metabolized and is stored (as fat). But there are several factors contributing to fat gain around your hips. For young women, they typically gain those "child-bearing" hips during puberty for obvious reasons. Age, gender, metabolism, genetics all play a factor. Watch the foods you do eat and exercise regularly with attention to the area you're trying to burn fat in and you'll get it. Diet, exercise, and dedication and you can do it.