On the Placebo Effect and Dieting

There’s nothing spectacular in this Wall Street Journal piece on the magic of placebos, but I thought this was an interesting paragraph concerning dieting:

Another study, published earlier this year in the journal Health Psychology, shows how mind-set can affect an individual’s appetite and production of a gut peptide called ghrelin (GREL-in), which is involved in the feeling of satisfaction after eating. Ghrelin levels are supposed to rise when the body needs food and fall proportionally as calories are consumed, telling the brain the body is no longer hungry and doesn’t need to search out more food.

Yet the data show ghrelin levels depended on how many calories participants were told they were consuming, not how many they actually consumed. When told a milkshake they were about to drink had 620 calories and was “indulgent,” the participants’ ghrelin levels fell more—the brain perceived it was satisfied more quickly—than when they were told the shake had 120 calories and was “sensible.”

Hence, the reasoning that the notion of dieting is altering our mindset, and we end up consuming more (since we know we aren’t getting enough food).

This reminds me of how using a bigger fork can help you eat less. Also, smaller plates and contrasting colors can dampen your appetite:

[Participants] were served different-sized plates filled with food. Those who were given larger plates filled their plates with more food than those with smaller plates. Those who were served food on tables with a higher color contrast between the plates and the tablecloth also ate more than those who were served the same amount of food without a noticeable contrast.

The problem with all of these studies is that by becoming conscious of how you’re trying to beat the system, you begin to override the placebo effect. In other words, if you made an effort to eat with a larger fork and using smaller plates, you can’t trick your brain for long: eventually, you’ll just compensate by eating more food (or more frequently). Show me a study where dieting is proved to conclusively work, and I’ll show you a millionaire.

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