Three ways to stop the swing

There isn't one right answer here, and I'm not going to pretend there is. There are three, and they suit different readers, and the decision in chapter 21 is to pick one and hold it for four weeks. I'll set them out and say who each is for.

The weigh day. You weigh once a week, on the same morning, in the same conditions, and write the number in the notebook by the scale. The rest of the week the scale stays where it is and you don't step on it. Once a month you look at the four numbers and see which way they point. This is for the reader who wants to keep an eye on things, who has a reason to know if their weight is moving, and who finds that one number a week is something they can read as a data point rather than a mark. The catch is that one reading a week is still one reading, and a bad weigh day can still swing. Chapter 18 is about how to take the swing out of it.

The average. You keep weighing every morning, but you never react to the number. You write it down without reading it, or you use a scale that records it and hides it, and on Sunday you average the seven and that's the only figure you look at. This is for the reader in a weight-loss programme, or one who's decided to lose weight and wants the evidence from chapter 6 on their side. It keeps the daily step the trials found useful and throws away the daily number that this book has argued is noise. The catch is that it takes some discipline not to look, and if you find you're looking, chapter 24 is for you and you should probably switch to one of the others.

The break. The scale goes in the cupboard for four weeks. You don't weigh at all. You notice what the mornings are like without a number in them, and at the end of the month you decide whether you want it back and on what terms. This is for the reader who doesn't need to change their weight, or who isn't trying to just now, and whose real problem is the swing. It's also for the reader who suspects the scale has become something they can't read as information at all, for whom even a weekly number would become a weekly mark. Chapter 19 is about the break and what to expect from it. The catch is the fear from chapter 7, which is real and which the chapter addresses.

All three share two rules. One step or none, never a second. And the number, when there is one, is written down and read as part of a column, never on its own.

Which one? If you're in a programme, the average. If you've a reason to watch your weight and you can bear a weekly number, the weigh day. If the mornings are the problem and the weight isn't, the break. If you're not sure, I'd take the break, because four weeks tells you the most, and you can always move to the weigh day afterwards with a clearer head.