Is nudge an effective public health strategy to tackle obesity? Yes

Rationale of nudging

The essence of the approach is to apply behavioural economic insights (for example, loss aversion—that losses tend to “hurt” more than gains of the same size) to policy considerations so as to change the choice architecture (that is, the environment). In the case of obesity, people with a tendency to overweight may place too much emphasis on immediate pleasures at the expense of future harms. In theory, changing the environment will make people more likely to make voluntary decisions that they would like to make and yet ordinarily fail to do so. The approach involves no compulsion: people are free to engage in the behaviour change intervention if they wish but are not required to alter their behaviour if they ultimately do not wish to do so.

No behavioural economist that I know would argue that nudges should entirely replace, for example, stricter forms of food legislation. Rather, nudges should be seen as an additional tool to complement regulation by moving society incrementally in a direction that might benefit all of us. Nudging should be seen as a “nuanced” approach—some policies might prove effective, and some might not; moreover, some of the effective policies may be judged politically or ethically unacceptable.

Nudges for obesity

The government’s nudge unit recently released a report that, among other policy proposals, listed several interventions aimed at encouraging healthier eating and exercise.2 Financial and non-financial incentives—that is, rewarding people if they meet a voluntarily agreed target behaviour or outcome—are mooted throughout the report. Unfortunately, simple incentives have not proved effective in motivating sustained weight loss,3 but the report suggests modifying the incentive according to behavioural economic principles in the hope that this will improve their effectiveness. For instance, by appealing to loss aversion, the incentive could take the form of a “deposit contract,” whereby people offer up their own money at the start of the intervention and receive the money back only if they achieve their target. Alternatively, given that people tend to give too much weight to small probabilities, the incentive could take the form of a very small chance of winning a large amount of money. Kevin Volpp and colleagues have started to test such mechanisms in the context of weight loss,4 so far with limited success, but there is far more scope for further experimentation of this kind.

A further behavioural economic finding, “hyperbolic discounting”—that is, that people place a heavy emphasis on immediate pleasures and pains—may also be usefully considered when designing policy. For many, exercising and eating healthily do not confer as much immediate pleasure as doing the alternative; the obesity recommendations in the nudge unit’s report propose a range of interventions intended to make these activities more enjoyable. These include a partnership with LazyTown, an initiative linked to a children’s television programme that has been operating in Iceland since 1996. Young children sign an “energy contract” with their parents that rewards them for eating healthily and being active. After introduction of LazyTown, childhood levels of obesity in Iceland started to fall.2 The nudge unit also raises the possibility of embedding musical sensors in stairs to encourage people to avoid lifts, which an experiment in Stockholm suggests could work.5

Most of the work in this area is at the ideas stage: little evaluative work has been done. That is because the field is new and developing. The beauty in the approach is that almost everyone can think up and pilot financially costless initiatives in their households or workplaces. For instance, marginally altering the salience of healthy foods may increase their consumption—a friend of mine has observed that the consumption of apples in her workplace increases noticeably when the apples are sliced and offered to her coworkers, rather than left whole in the fruit bowl. Of course, in tackling obesity, the nudge approach will be no substitute for regulation of the food and drinks industry, but it may nonetheless serve the social good.