All the energy that you eat at supper-time, is never used, it is all stored as body fat while you sleep. Also, while you sleep is by far the best time for your body to use it's stored reserves of fat. If you want to lose weight, then reduce supper to nothing - you may have to do this gradually - then do a little exercise before you get into bed: and I really do mean a little!
watch what you eat.
eat small portions but don't be anorexic or bulimic.
make sure it's not junk food.
drinking lots of water is great only if you work out, if not your body will retain the water.
running is the most effective way, cardio of any type is also good.
& an ab workout & lift weights to become tone.
& make sure you take vitamins.
You said no dumb answers, but somehow I doubt I'll be telling you what you want to hear, even though this'll doubtless be more true than the others you get. Not everyone is made to be thin. The only way you can tell if you're a healthy weight is if you exercise regularly and eat healthy. Whatever weight you achieve and maintain from that, unless there's a condition that affects your weight otherwise, is your healthy weight.
Fat in itself isn't unhealthy. Rather, it can be a symptom of other unhealthy lifestyles or conditions. But contrary to what those popups and banner adds would like you to believe, there's no one-size-fits-all way to be skinny. For some people, it's literally not possible.
Read this: http://kateharding.net/faq/but-dont-you-…
Start with what I linked, and go on to other articles that sound interesting to you. It may seem like BS at first, but trust me, you'll feel better about life by the time you get through some of it.