The Immune Response Diet

What's it about? This is a tailor-made diet based on scientific research which shows that, if your body has an allergic reaction to certain foods and they're not processed properly, you eventually gain weight. If you can cut those foods out of your diet for even a short amount of time, your energy levels will shoot up and you'll burn off stored fat more easily.

First you need to send off a blood sample to a laboratory where it's tested to see which of 112 common foods your body has inflammatory responses to. You're then sent a personal diet sheet listing the foods you can eat freely, then those you should avoid for five weeks, 10 weeks and three months.

Research shows that people following this diet can reduce their body weight by as much as 10 per cent in just five weeks, without changing the number of calories they eat.

Would appeal to?: Yo-Yo dieters who've tried lots of different diets and failed and anyone who suspects they've got food allergies. As long as you avoid foods as directed, you can eat as much as you like, so it's perfect for people who can't stand counting calories.

Expect to lose: Up to a stone in the first month.

Celebrity fans: Ali Cockayne and celebrity party organiser Fran Cutler.