Meal Memory
Meal memory is the idea that part of what stops a person eating is remembering that they have already eaten. On this account the end of a meal is not settled by the stomach alone. It is settled partly by a record in the mind of what was just consumed, and weakening that record tends to raise how much gets eaten later.
What it is
The existence proof is one of the strangest studies in appetite research. Paul Rozin, Dow, Moscovitch and Rajaram, in 1998, offered a second full lunch to two densely amnesic patients, ten to thirty minutes after each had finished the first. Both ate it readily, and usually started a third. Control participants refused.
This was two patients. Say "two patients" plainly, out loud, every single time this study is used. It is a case study and an existence proof, not an effect size and not a result about a population. Used that way it is extremely strong: it shows that something other than the state of the stomach is doing the stopping. Used any other way it is overclaiming.