Non-technical Summary:
Once viewed as an issue only in affluent countries, obesity has become a global concern following the dramatic increase in obesity in low- and middle-income countries. Excess body weight not only harms people’s health by raising the risk of cardiovascular disease, stroke, diabetes, and some cancers, it also reduces economic well-being by constraining economic participation, decreasing productivity, and reducing income. Many of the risk factors driving these illnesses (e.g., tobacco use, alcohol abuse, unhealthy nutrition, limited physical activity) are preventable, raising questions about why some people make heathier choices than others. Answering this question has the potential to enhance public health efforts to combat the global rise in obesity and obesity-related noncommunicable diseases.
Our research examines the relationship between limited self-control and both objective (obesity, BMI, waist-to-height) and subjective measures (weight satisfaction, ideal vs. actual weight) of unhealthy weight. While much of the existing evidence comes from small, selected samples, we make an important contribution by exploiting data from the Household, Income and Labour Dynamics in Australia (HILDA) Survey. The HILDA Survey is one of only two population representative data sources that now include a well-established measure of trait self-control – the Brief Self-Control Scale (BSCS) (Tangney et al., 2004). The Self-Control Scale is the most widely used measure of trait self-control in psychological research on self-regulation and self-control.
We find that those with limited self-control have an unhealthier body weight and poorer subjective weight-related well-being. Thus, there may be beneficial population health consequences from supporting people’s capacity for self-control. We then develop an empirical method that uses the 13 items in the BSCS to isolate two core factors shaping people’s self-control – impulsivity and restraint. Our results show that high impulsivity and low restraint are only modestly correlated; each has differential predictive power. While body weight, physical activity and dieting are more strongly associated with people’s restraint, their degree of impulsivity is more important in understanding their decisions about when, where, and what to eat.
These insights have important implications for the specific policy tools we use to address unhealthy weight. If the goal is weight reduction, improving weight-related subjective well-being, or increasing physical activity, then our results indicate that the policy focus should primarily be on increasing restraint rather than reducing impulsivity. Impulsivity is relatively more important if we wish to influence when and where people eat or improve their nutrition levels. Given this, we may be able to improve dietary self-control through interventions that slow decision making down or speed up the processing of food’s health attributes. One potential strategy for achieving this may be for policy to target the `time price’ of food consumption by increasing the time it takes to purchase and consume unhealthy food, while decreasing the time necessary for the purchase and consumption of healthy food.