...number of calories burned in one minute by vigorous kissing: 26; banging your head against a wall: 2.5
number crunch, Good Weekend, 2005

Commercial diets are often accused of failing. This is based on the premise that great numbers of people are on a diet at any one time, and that many people regain some of the weight they have lost. But no-one knows how many people are trying to lose weight, because a proper survey has never been carried out.

The accusation that 'diets don't work' is unfair because most reputable, well-researched diets - if followed correctly - will help with weight loss. After that, people are on their own, and the fact that they regain weight is hardly the fault of the diet.

This is where the Cambridge programmes differ, because everyone who tries one agrees to join a four-stage process:

1. preparation

2. weight loss

3. stabilisation

4. maintenance