Fats in foods like potato chips and french fries make them nearly irresistible because they trigger natural marijuana-like chemicals in the body called endocannabinoids, researchers at the University of California, Irvine, have found.

The researchers discovered that when rats tasted something fatty, cells in their upper gut started producing endocannabinoids, while sugars and proteins did not have this effect.

How fats create, like, a buzz

It starts on the tongue, where fats in food generate a signal that travels first to your brain, and then through a nerve bundle called the vagus to your intestines. There, the signal stimulates the production of endocannabinoids, which initiates a surge in cell signaling that prompts you to totally pig out — probably by initiating the release of digestive chemicals linked to hunger and satiety that compel us to eat more. And that leads to obesity, diabetes and cancer, the researchers said.

But they suggest it might be possible to curb this process by obstructing endocannabinoid activity: for example, by using drugs that “clog” cannabinoid receptors. The trick: bypassing the brain to avoid creating anxiety and depression (which happens when endocannabinoid signaling is blocked in the brain). I’m guessing McDonald’s won’t be adding that drug to their fries.

Ref.: Daniele Piomelli, et al., An endocannabinoid signal in the gut controls dietary fat intake, PNAS, 2011; in press