Seriously though, I fail to see how people can ignore caloric content when factoring in losing weight. For people without a naturally thin body, body fat is more easily accumulated. One of the biggest dangers in failing when trying to lose weight is not sticking with it.
Let's say you change your diet. Your body will somewhat adjust by lowering your metabolism. But if you exercise sensibly (including both anaerobic and aerobic) you will raise your metabolism. There is no mystery here. You will be taking in less calories than you are burning. They extra energy HAS to come from somewhere, that's just physics. Fat is the easiest thing to burn. If are being reasonable with your calorie reduction, say 300 less per day on average than pre-diet, the metabolic bounce will level off pretty quickly and you'll begin to lose weight. The trick is monitoring caloric content. Since your metabolism is higher, your body will want to eat MORE, not less.
Now, say you fall off the wagon. You go out for a weekend bender and don't exercise. Your metabolism is still naturally raised, but the lack of exercise means you burn a few hundred calories less. And you eat what you want because you've "been good all week". You will tend to overeat for a few reasons (body craving, psychological, emotional) and due to the nature of the food (McDonalds anyone?) you'll likely take in hundreds of calories over your pre-diet levels. Bingo, you just PUT ON weight. And likely more than what you lost in the week.
The more drastic the cut in calories the more prone your body is to suffer this fate, hence why I suggest you go slowly.
To do this though, you need to know how many calories you ingest on a normal day, then dial it down. Also, you can cheat a little here and there, just compensate the next day so that in a week, your average is the target level. I found this much easier, as you sometimes need a piece of pizza. The next day, eat more salad and less spaghetti.
And as healthy as some foods are, you still need to control portions or you'll never win.
Don't let anybody tell you you'll fail, nor that you are naturally fat and can't do anything about it. Sorry guys, but that's just stupid. Anybody can lose weight, including bears.
BTW, I lost 35 pounds of mostly belly fat a few years ago. In two months. I wasn't always this slender sexy bitch you see now.