How does the Fast Diet work?
(A TDEE / BMR / BMI calculator)
If we were to distill the Fast Diet into a single sound-bite, it would all come down to 5:2. That’s five days of normal eating, with little thought to calorie control and a slice of pie for pudding if that’s what you want. Then, on the other two days, you reduce your calorie intake to 500 calories for women and 600 calories for men.
Since you are only fasting for two days of your choice each week, and eating normally on the other five days, there is always something new and tasty on the near horizon. In short, it’s easy to comply with a regime that only asks you to restrict your calorie intake occasionally. It recalibrates the diet equation, and stacks the odds in your favour.
Bear in mind that the programme is designed as a well-signposted path towards a longer, healthier life; weight loss is simply a happy adjunct to all of that.
How many calories on a non-Fast Day?
You may have wondered how we came up with the recommendation that women have 500 calories and men have 600 calories on a Fast Day. We used the rule of thumb that women need 2000 calories and men need 2400 calories per day and on a Fast Day you should eat a quarter of a normal day’s recommended calories. Some of you have also wondered exactly how many calories you should be eating on days when you’re not fasting.
We thought we’d bring everything together in one place for you so you can do the calculations here. You can use the calculator on the right to calculate your BMI, BMR (basal metabolic rate) and TDEE (total daily energy expenditure). We’ll go into these in more depth below.