"I know what to eat, I just don't do it"

A lot of readers will say they don't need to be told what to eat. They know. Vegetables, protein, not too much, not too many biscuits. The problem is doing it, and rules are how you make yourself do it.

I'd separate knowing from rules, because they're different things and the diet has fused them. Knowing is what you'd feed a friend who came to stay for a week. You'd make them breakfast, lunch and dinner, mostly ordinary food, some vegetables, a pudding now and then, and you wouldn't weigh anything or count anything or forbid anything. You'd feed them well and they'd eat well, and nobody would call it a diet. That knowledge is real and you have it.

Rules are something else. Rules are "no bread", "nothing after seven", "twelve hundred a day". They don't come from what you know about feeding a friend. They come from the plan, and they're designed to produce weight loss fast, and chapter 3 is about what they produce along the way. When you say you know what to eat but don't do it, I'd ask which you're not doing. If it's the friend's meals, that's worth looking at, and chapter 19 is about it. If it's the rules, then not doing them is what everyone does with rules, and it isn't a failure of knowledge or of will.

The NHS's advice on eating for weight, if you want to see how little it asks, fits on one page. Don't lose weight suddenly with diets. Don't skip meals, because you'll snack more. Don't finish your plate if you're full. Aim for half a kilogram to a kilogram a week if you're trying to lose. Get your five a day. Swap sugary drinks for water. Share your plan with someone. That's it. There's no forbidden food on the list and no number to count, and it reads like what you'd do for a friend.

So the belief in this chapter is half right. You do know what to eat. What you've been trying to do instead is follow rules, and rules aren't knowledge, they're restriction with a name, and the envelope is the record of what restriction does to you.