If you have opened this article hoping for a miracle one-step solution to long term weight loss which involves eating no carbs after 6pm, fasting twice a week or drinking a particular brand of shake, then I am afraid you will be very disappointed.

Over the course of my 20-year career, I have in fact been emphatically anti-diets, so it may seem odd that I have now written a book devoted to one. It's no U-turn; The Fast Diet, co-written with Dr Michael Mosley, works so brilliantly because you don't have to give anything up at all.

With the new 5:2 diet craze sweeping the nation -- where dieters restrict calorie intake for two days (to 500 calories for women and 600 for men) and ...

Let's take slimming clubs as an example. WeightWatchers and Slimming World have on the surface quite sensible ideas around cutting the bulge. But both brands promote a range of processed products (bars, shakes etc.) that could be seen as easy replacements for other lower calorie, non-processed and cheaper food.