Before you start

This is a short book and you can read it in two or three sittings. It's about one habit. You open a bag of crisps, or sweets, or a tub of something, meaning to have a few, and some time later your hand goes in and finds the bottom, and you're surprised, and slightly disgusted, and you'd have said an hour ago that you didn't want that many. You didn't. You ate them anyway, because the packet was open and the programme was on and your hand knew the way.

I'm going to argue three things. The first is that the habit makes sense from the inside. You like crisps. A few is a reasonable intention. And the bag is right there. The second is that the intention never had a chance, because people treat a unit as the right amount and the packet is the unit, sized by someone who wasn't thinking about your evening. A bag hides how much has gone, so the only signal it sends is the bottom. Eating with a screen on raises how much you eat now and later. And the pleasure you opened the bag for is in the first few and fades within minutes, so the run to the bottom destroys the very thing it was meant to enjoy. The third is practical. You put what you're going to eat in a bowl, you put the packet away, and you eat it without a screen. Chapters 20 to 23 cover how.

This book doesn't ask you to stop eating crisps, or sweets, or anything you like. It doesn't ask you to count anything. It asks you to change the unit, so that "a few" is what you eat, and to look at them while you do.

One caution. If the run is large, if it comes with a feeling of losing control, and especially if it's followed by making yourself sick or by not eating for a stretch, that isn't the habit this book is about. It may be an eating disorder, which is an illness with good treatment. The charity Beat and your GP are the places to start. This book is about a sharing bag on a sofa.

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.