According to the principles of the zone plan, by following a strict diet that divides every meal into 40% carbohydrates, 30% protein and 30% fat, you are able to lose weight. Carbohydrates are carefully controlled and the diet allows more lean protein consumption than most people are used to.
The Zone diet encourages you to eat throughout the day - every five hours at least. All that snacking means you're less likely to be tempted by sweeties and crisps. It also encourages you to eat a good selection of fruit and vegetables and takes a healthy low-fat approach.
Governmental healthy eating guidelines recommend that 50% of a healthy diet should be carbohydrate and the Zone diet falls short of this. In fact, low carbohydrate diets like the Zone diet can lead to low energy levels and make exercising difficult. Also, the Zone's complicated ratio system makes it near-on impossible to work out how much of everything you can actually have in real life - terrible when you're hungry and enough to make you run screaming to the nearest McDonald's.
Does it work?
Yes it does. But you have to take into account that the Zone is simply a low-calorie diet that's presented in an incredibly unsimple way.