Chladni Plate

The Remarkable Power of an Open-Label Placebo for Weight Loss

The remarkable power of an open-label placebo comes through in a new study appearing in Scientific Reports. The power is remarkable simply because “open label” means that everyone receiving a placebo knew that it had no medicinal effect whatsoever. And yet, compared to usual care for overweight and obesity, people lost more weight after four weeks of taking a placebo twice daily.

The difference was 2.6 pounds – not a lot, but statistically significant nonetheless.

Placebos Added to Behavior Change

This was a small study – 57 individuals with an average BMI of 29 at the start of the study. Researchers randomly assigned them to receive the twice daily placebos or not for the four weeks of the study. All participants received detailed guidance on the exercise strategy and lifestyle changes for weight loss based on recommendations of the WHO.

Even though people in the placebo group knew they were getting placebos, those placebos had effects. In addition to losing more weight, the placebo group reported less disinhibition of eating behavior. That is, they were more susceptible to eating in response to emotional or situational cues to eat.

This is an odd combination of outcomes.

Learning from Puzzling Results

The authors of this study say “we believe that the results are encouraging to further examine this treatment [open-label placebos] in obesity. But that is not the learning we take home.

Rather, we see this study as a cautionary tale in two dimensions.

First it is a reminder to be cautions when we hear about new drugs that deliver good outcomes in early, short-term trials. Sometimes a short-term effect in obesity does not hold up for the long term – as we certainly suspect would be the case for open-label placebos.

Second, it reminds us that the point in treating obesity is not weight loss for its own sake. Rather, it is to help a person improve their health. We see no evidence in this study for a health benefit – let alone a benefit that lasts.

So yes, this study offers us helpful insights. But the helpful insight is a word of caution about small studies with results that sound too good to be true.

Click here for the study, here, here, and here for other observations on placebo effects in obesity and health.

Chladni Plate, exhibition photograph by Matemateca (IME USP) / Rodrigo Tetsuo Argenton, licensed under CC BY-SA 4.0. Click here for more on Chladni Plates.

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October 5, 2024