] A single infusion of an intestinal hormone made people eat
] less for the rest of the day, regardless of whether they
] were fat or thin, researchers are reporting today.

I've long wondered about this... That sometimes it's not activity level or willpower or self-esteem or anything like that, but simply something in the body that turns appetite on and off. I know that sometimes I sit down to a fast food meal and want to finish every last french fry, while at other times I go halfway through the box and then suddenly I'm just plain not hungry any more, so I toss the rest away uneaten.

Study Finds Appetites Reduced by Hormone