A new study from Rutgers University might offer a biological reason for why you can’t eat just one. It’s a hormone called glucagon-like peptide-1, which is partially responsible for letting your body know it isn’t hungry anymore once you’ve eaten enough food to meet your caloric needs.

Researchers found that mice whose brains had lowered amounts of GLP-1 ate more food than mice with normal levels of the hormone. The GLP-1 deficient mice also preferred food with a higher fat content than the control group.

Of course, this single hormone isn’t solely responsible for appetite, especially in an organic system as complex as a human being, where issues like conscious choice and willpower come into play. Certainly people aren’t slaves to sequences of amino acids like laboratory mice. Right?

It depends who you ask, because now we run into the problem of free will. Are you deciding to eat that cookie, or are your hormones? Is there a difference? If you end up fat either way, does it really matter?

Tasting temptation

If you view choices, nutritional or otherwise, as a moral dilemma, with a right answer and a wrong answer, then avoiding the cookie is an issue of temptation. Sure, maybe your brain is low on GLP-1, but that just means it’s harder to resist. Like an addiction, the important part is not giving in.

"Thinking about your body a bit more like a predictable machine can actually help you make better choices about your health."

But if you’re some kind of dietary Calvinist, the decision whether to eat the cookie has already been made for you by the chemical soup in your brain. Too little GLP-1 and other appetitie-suppressing hormones? The cookie gets eaten. It’s the illusion of a decision, because your body has already determined your actions.

That’s an odd perspective for many Westerners to wrap their heads around, at least when it comes to physical health. We like to believe we’re in control. But thinking about your body a bit more like a predictable machine can actually help you make better choices about your health.

When the cookie is no longer a moral obstacle but a scientific one, motivation becomes less important. Only results matter.

  • Fact: If given the chance, you will eat the cookie. You are powerless before the cookie.

  • Ergo: Don’t give yourself the chance to eat the cookie. You are a strong, independent organism that don’t need no cookie.

  • Stratagem: Don’t keep cookies in the house. If you see cookies in the wild, don’t pick them up. Remember that GLP-1 deficient mice ate even when they didn’t need food, and the food they ate was worse for them. Filling up on healthier foods won’t stop you from eating the cookie if you encounter it.

Another option is to sate the desire but remove the consequences. That’s the idea behind fat or sugar replacements like Olestra or aspartame. Eat the fat-free cookie and all is well, as long as you ignore the accounts of the intestinal lava these substitutions can invoke.

The Rutgers researchers are trying a third option: fixing the organism. They’d like to see targeted treatments that adjust the level of GLP-1 in the brain, a tactic that heads straight to the source of the problem

In the meantime, if you do eat that cookie, don’t beat yourself up too much. You couldn’t help it.