For over thirty years, behavioural scientists have investigated so-called ‘restrained eaters’ (Stunkard & Messick, 1985). These people, and to some extent I still count myself among them, tend to eat less than they would really like at mealtimes, and often think about their weight and what they’ve recently eaten in order to decide how much to eat. In other words, rather than eating when hungry, and stopping when full, restrained eaters think things like, “well, I did have that big bagel for breakfast, so I’d better have less for lunch,” or “I ought to be sensible because I’m going out tonight and I know I’ll order a big meal then,”…