Why Do We Eat So Much When It's So Easy Not To?

Nov. 22, 2006 — -- Eat fewer calories than you burn.

Exercise more, eat less.

It sounds so easy. Both of those formulas are foolproof. Anyone who follows them will lose weight, baring some kind of medical problem. Then why is it so hard to keep that old waistline where it's supposed to be?

Because eating, many scientists contend, isn't just about eating.

Other animals, much lower on the evolutionary scale, have figured it out. Take the African cattle tick, for example. Female ticks don't have to worry about gaining too much weight, as long as the female remains a virgin. But once she crosses that point of no return, she gorges like mad, increasing her weight by ten-fold within 24 hours, according to researchers at the University of Alberta.

So, if she wants to remain slim, all the female tick has to do is remain chaste. Probably wouldn't work for humans, though. We're too caught up in the sociological aspects of eating, say scientists at a number of universities. Who we are eating with, and what kind of food seems to be socially acceptable, has more of an impact on how much we eat than feelings of hunger or fullness.

In fact, according to researchers at the University of Toronto, our biological needs have little to do with how much we eat. They've even come up with a name for it.

"Eating occurs within what we have termed a zone of biological indifference, in which the individual is neither genuinely hungry nor genuinely sated," says psychology professor Peter Herman.

A "zone of biological indifference"? Need to chew on that tidbit for awhile. Herman says we are rudderless when we are eating, paying more attention to our companions than we are to what we are eating, and thus we eat more than we really need.

Scientists at Cornell University have reached a similar conclusion. David Levitsky, professor of nutritional sciences at Cornell, says environmental cues, not biological mechanisms, are a big part of how much and what we eat. Even "feeling stuffed" doesn't shut off the appetite, he says.