If you're heavily muscled, that could be a fine weight, but if you're not, then it's just fat. I'm the same height and for years I was pretty much the same size, but when I started doing martial arts and lifting weights I got bigger and I weigh more -- I'm a larger person. I'm not huge, but my physique is just more filled out. As for diet, what you want is to eat a balanced diet on a regular basis, and limit sugar and simple carbohydrates which turn into sugar quickly and if not burned quickly store as fat. But you say you have a good physique, which if true would indicate you're not seeing extra fat. Are you sure your BMI is too high? Usually you can see the flab if that's so.