The decision

Here's the rule I'm suggesting.

I eat sweet things with a meal, because I like them. Between meals, the tin stays shut.

It has six parts.

With a meal means as part of breakfast, lunch or dinner. Pudding after dinner fits the rule, and so does a couple of squares of chocolate with your coffee at the end of lunch, or jam on your toast at breakfast. This is the NHS advice for teeth, which is to limit sugary foods to mealtimes, and it separates sugar from the three jobs, because a meal isn't a reward, a pick-me-up or a comfort. It comes round at its usual time whatever kind of day you've had.

Because I like them means you choose it and you taste it. Have the thing you really enjoy, in a sensible portion, on a plate, sitting down, and pay attention to it. A pudding you look forward to and eat slowly gives you more pleasure than the seven distracted items of that Thursday. If you find you don't much want pudding on a given day, don't have it.

Between meals, the three jobs go to their replacements. Finishing something gets a pause, a message and a proper break. The afternoon wall gets a walk and a glass of water. An upset gets ten minutes, a hot drink or a phone call. Chapter 15 has the details.

Hunger between meals gets real food. Fruit, nuts, cheese, toast and yoghurt are all fine. The rule doesn't ask you to go hungry, and you should never be gritting your teeth through genuine hunger because of it.

Occasions are occasions. A birthday, a wedding, Christmas Day, or a friend who's baked a cake and cut you a slice are all things to enjoy wholeheartedly. An occasion has a date and involves other people. "It's Thursday and I've had a day" isn't one. If your workplace produces cake most days of the week, chapter 17 has a section on that.

A lapse is just a biscuit. At some point you'll find yourself at the tin at nine in the evening. When that happens, enjoy the biscuit, put the lid back, and carry on as normal at the next meal. Don't skip pudding tomorrow to make up for it, and don't decide the week is ruined. Chapter 3 described how bans and collapses feed each other, and guilt over a lapse is how that cycle gets started again.

Alongside the rule, make two changes to your surroundings, since chapter 13 showed how much they matter. Move the tin away from the kettle to somewhere inconvenient, such as a high cupboard or the back of the larder. And stop buying sweet things in advance for the three jobs. Take the chocolate bar out of the desk drawer, and don't keep emergency supplies in the car. Buy the pudding you plan to eat with meals and leave it at that.

Plans of the "when this happens, then I'll do that" kind make a decision much more likely to survive a tired afternoon. Peter Gollwitzer and Paschal Sheeran pooled 94 tests of such plans and found that they made people a good deal more likely to follow through. Here are three, which you can adapt.

When I finish a piece of work and think I've earned something, then I'll send one message saying it's done and take my tea outside.

When I hit the wall in the afternoon, then I'll walk for ten minutes before I decide anything else.

When I put the phone down upset, then I'll put the kettle on and sit with the feeling until the tea is drunk.

As for what to expect, this is my expectation and not a finding. For the first two or three weeks you'll reach for the tin many times a day and find it isn't there, as chapter 3 described. Each time is slightly uncomfortable for a minute or two and then passes. The eleven o'clock reach tends to fade first, because nothing much was behind it. The evening one takes longest. Your afternoons should improve within days, if the evidence in chapter 5 applies to you. After a couple of months, going by the Monell study, sweet things will probably taste sweeter to you. I can't tell you what will happen to your weight, and I'd rather you didn't make that the test.