So here's a little "think yourself thin" thing. Once again there is an idea for a diet steeped in common sense that probably won't work for most people.
The problem with dieting is the focus on weight loss. This is also a problem within the medical community where there is a larger emphasis placed on getting the right BMI (a semi-useful tool that is way over used) rather than simply being healthy.
Eating well and exercising is the best way to lose weight, but it is not a guarantee of weight (fat) loss. The reason is that losing fat--particularly the subcutaneous kind which doesn't start to drop until after the muscular fat is used up--is actively opposed body. When a body activates the processes that use fat (instead of sugars) to get energy it signals starvation. When the body is starving it reacts by shutting down energy burning processes and by triggering "cravings" for foods that are high in sugar/starch content.
This makes losing weight very difficult. It is biology in action and it is a remarkable thing, but the only way to overcome it is to be aware and stick to it...or not.
It is possible to be healthy and overweight, just like it is possible to be thin and at risk. A healthy diet and exercise provide benefits that go beyond a thinner waist, and when dress size/pant size doesn't start dropping it should not lead to frustration. If you eat right and exercise you will be healthier and likely live longer, even if you don't lose a quarter inch from your waist...with muscle development you may even gain.
If we stick to a healthy lifestyle rather than overconsumption, then the next generation will never fall into the obesity trap that we have now.
...Of course with the rising cost of food and energy there may be no choice soon but to eat little and eat healthy.