Obesity has long been assumed to stem from one of two causes: genetic predisposition or an insatiable appetite. The former elicits pity, while the latter tends to provoke sneers, judgments and an assumption that the person in question simply lacks self-control.

According to a study released earlier this week, we may have been wrong all this time about why so many people don't stop when they're full. It may have nothing to do with liking food, but with the opposite.

The researchers, who published their findings in the journal Science, monitored the brain activity of women as they ate chocolate milkshakes. While the scans taken prior to eating were in line with what previous research had suggested -- that people who overeat tend to anticipate greater rewards from eating -- it was the scans taken during the eating process that offered the biggest surprise: there was less activity.

This means that the women who anticipated the greatest pleasure from the milkshake actually derived the least, and the researchers believe they may want to eat more in order to compensate for that lack.

This seems about right, actually. Think about cigarette smokers, drug addicts, sex addicts -- anyone prone to compulsive behavior. The more an addict smokes, does a given drug, or engages in compulsive sexual activity, the more he or she will do so. Why? Because of tolerance. If a single cigarette, bump of coke or glance at a pictorial in Penthouse no longer satisfies the urge, the addict ups the ante. Hence three-packs-a-day smokers, raging coke heads, incurable porn addicts and people who can't stop eating.

The findings could provide a new way of viewing overweight people: less as gluttons, more as addicts. And if we agree that addiction is a disease -- as most enlightened people do these days -- perhaps we can begin treating those who overeat with greater empathy and more effective remedies.

[Image: AutoCCD from Wikimedia Commons]