What is it? An app that tracks your calorie input and output. Also, the only way I can ever lose weight.

How much does it cost? Free to download. Your only payment comes in the form of guilt and embarrassment.

What does it promise? The makers claim that keeping a food journal can double your weight loss.

What’s it actually like? In the nicest possible way, using MyFitnessPal is like having someone’s foot on your throat. Of all the faddy schemes designed for weight loss, having an app that confronts you with cold statistical fact is by far the most effective. You enter a goal weight, and the app calculates a daily calorie intake. Whenever you eat anything, you enter it into MyFitnessPal – either manually or by scanning a barcode – and it knocks those calories off your total. Then, when you exercise, you enter the number of calories you’ve burned and it chucks them back onto your total. Without trying, the app makes you want to exercise (so that you have a bigger total) and eat better (so you don’t blast through your total like a gruesome lardy poobucket). I’ve been using it for a few weeks, and already I have old shirts that do back up again. MyFitnessPal works, but it can be a cruel mistress.

Best and worst bit The fact that MyFitnessPal works is obviously the best bit. But it has turned me into the least desirable type of calorie bore. And, God, what I’d do for a cream cake.

Is it worth it? Most definitely.