Nudges Meet Stubborn Humans and Complex Systems in Obesity

Nudging the behavior of consumers seems like an appealing strategy for overcoming the rise in obesity and the harm it is causing to population health. Apply a little behavioral psychology and voilà! People make healthier choices. The appeal is so strong that the UK government is counting on supermarket nudges to overcome obesity and save the National Health Service there.

A new paper in Applied Economic Perspectives and Policy suggests the government had better be ready with plan b. It seems that this appealing theory might hit a brick wall. When nudges meet up with stubborn humans who don’t like being nudged and complex systems that adapt to keep on promoting obesity.

Psychological Reactance

David Just and Gnel Gabrielyan tested the concept of nudges to promote healthier choices with an experiment to test four interventions. The point was to nudge people toward consuming less of an unhealthy snack food. In a controlled setting, the nudge worked well enough. But the trouble is that when people figure out the nudging, they do the opposite. In this experiment, Just and Gabrielyan let one cohort know the purpose of the nudging. Classical reactance kicked in and the people in that cohort increased their unhealthy snacking by 93%.

Reactance occurs when people feel like their choices are being limited or taken away. It leads them to do the opposite of what’s being asked and resent restriction. This might explain why nudging loses its effectiveness over time.

Implicit Bias About Obesity

The other fundamental problem with relying on nudges to overcome obesity is that such reliance springs from implicit bias about obesity. Most people presume obesity is a problem of bad choices. Some say it out loud. Others may have this bias without ever thinking much about it. “Let’s make the healthy choice the easy choice” has a great appeal because of this bias.

But the truth is that it takes more than healthy choices to overcome obesity. Obesity is a complex condition driven by complex factors of biology and the environment in which we live. Urging, berating, or even gently nudging people to make better choices does little to overcome it unless we work on all the other factors in play.

Click here for the study by Just and Gabrielyan, here for more on the UK’s reliance on nudges to “tackle” obesity.

Choose, photograph by Tony Webster, licensed under CC BY 2.0

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July 13, 2025