If no diet has turned out to be a silver bullet for weight loss, then what could explain why some of them at least seem to work, at least for some time? In looking at our rampant dieting culture, I realized that there are a lot of elements that remind me of the placebo effects we see in other parts of our lives. And this got me thinking: Perhaps it’s not the contents of the diet that matters. Perhaps it’s simply the act of dieting. Is it possible that, rather than the specifics of the food regime you undertake, it’s the mere act of starting a diet—any diet—that makes you thinner? Could it be that the inherent placebo effect that comes with any diet is what’s causing you to lose weight?

The connection between brain chemistry, eating habits, and weight is nothing new. Our decisions to eat are based on brain chemistry, and the results of those decisions tend to affect our size. We know that stress hormones generated by dieting and other forms of starvation affect how our bodies process fat. Some studies even suggest that deficiencies in certain mood-moderating brain chemicals shape which junk foods we prefer: People with low dopamine crave sweets, those lacking the neurotransmitter acetylcholine crave fat, and those without serotonin try to eat all the starch they can get. So brain chemistry and metabolism are intimately linked.