Firstly, we must not eat too many calories. The best way to achieve this is to replace dense carbohydrates, like rice and cereal and pasta and bread and cakes and icecream, with low density high fibre vegetables and fruits. By doing this we'll also stop producing too much fat storing insulin, and we'll get all the wonderful benefits of an increased vitamin and mineral intake. We must also ensure we eat enough protein, not only because it's structurally crucial, but also because it promotes the secretion of glucagon, the hormone essential for the mobilisation and use of body fat. And finally we need to eat fat, preferably some every meal.
Fats are also structurally crucial, and are a great source of energy.
Fats supply the building blocks of many important hormones, and by slowing the entry of carbohydrates into the blood dietary fat has a favourable affect on the balance of insulin and glucagon. The Zone diet perfectly satisfies all of these requirements. I hope by now you can see why the healthy loss of body fat is not possible on a high carbohydrate diet. Even if excess carbohydrates don't get stored as fat, they still must shoulder much of the blame for obesity because of the hormone imbalance they create. The successful, healthy, and lifelong elimination of obesity requires us to live in a continuous state of hormonal balance.