Before you start

This is a short book and you can read it in two or three sittings. It's about one habit. Several times a day, between meals, you eat something sweet, and each time you have a reason. Sometimes you've finished a task and earned it, sometimes you're flagging and need a boost, and sometimes you've had a bad phone call and want comforting. The biscuit, the chocolate bar or the slice of cake is doing a job for you each time.

I'm going to argue three things. The first is that the habit is understandable, and that it isn't an addiction in the sense people often fear. The second is that sugar does each of its three jobs badly. As a pick-me-up it leaves most people more tired within the hour. As a comfort it gets the credit for a recovery that would have happened anyway. As a reward it's poor pay that you award yourself on easy terms. I'll give the evidence for each of those, and I'll be straight about the part that's true, which is that a sweet thing does give you a small lift for a few minutes. The third is practical. You go on eating sweet things, with meals and because you like them, and you stop employing them between meals. Chapters 15 and 16 cover how.

Nothing in this book asks you to give up sugar, pudding, birthday cake or chocolate. I don't think sugar is poison and I won't describe it as one. This isn't a diet book and I make no claims about your weight. The argument is about the jobs you give sugar to do, and whether it does them.

Three cautions.

If you have diabetes and you use sugar to treat low blood sugar, nothing here applies to that. The NHS advice for a hypo is to eat or drink something that raises your blood sugar quickly, such as a small glass of fruit juice or a few jelly babies, and that advice comes first. If you have diabetes of any kind, talk to your diabetes team before changing how you eat.

If your eating sometimes feels out of control, this may be more than a habit. The NHS describes the main symptom of binge eating disorder as eating a lot of food in a short time and not being able to stop when full. Other signs it lists are eating when not hungry, eating alone or secretly, and feeling depressed, guilty, ashamed or disgusted afterwards. If that sounds like you, the NHS advice is to see a GP as soon as you can. If you have or have had any eating disorder, please take advice from whoever is treating you before following a book that sets rules about food. The charity Beat runs helplines.

And if you're going through something hard at the moment, such as a bereavement, an illness or a very bad stretch at work, this may not be the month to change anything. The tin will keep.

The notes at the back give my sources and their limits. Where I'm giving my own reasoning and not a finding, I'll say so.