I dont think youre overweight. maybe you just need to tone up a little. try sit ups and stomach crunches and yoga. try changing your diet. switch chocolate bars for cereal bars, white bread, pasta and rice for wholemeal, snack on fruit instead of uhealthy things such as crisps. eat fish and white meat like chicken instead of red meat. cut out fast food, and have lots of veg with your meals. switch full fat mayo, salad dressings etc for low fat. dont deprive yourself of everything you like though, one a week or so have a chocolate bar, have a take away once a month, they are ok in moderation! drink plenty of water, at least 2 litres a day. you should feel a lot healthier for doing this, and will notice the difference in your skin and hair. i dont really think that bmi thing is that accurate, people who do a lot of exersice will prob weigh more as they will have more muscle, but they wont be overweight.