What is known about the effectiveness of economic instruments to reduce consumption of foods high in saturated fats and other energy-dense foods for preventing and treating obesity?

Summary

The issue

Overweight and obesity are increasingly prevalent in Europe. In the European Region, the growing prevalence of overweight – a body mass index (BMI) over 25 kg/m2 – ranges from about 25% to 75% of the adult population. Up to a third of the adult population, about 130 million people, are obese – with a BMI over 30 kg/m2. Overweight and obesity are also increasingly prevalent among children. This synthesis summarizes the available evidence concerning the effectiveness of economic instruments (including taxes, price policies and incentives) in containing or reducing food consumption, particularly of foods high in saturated fats and other energy-dense foods.

Findings

This review found no direct scientific evidence of a causal relationship between policy-related economic instruments and food consumption, including foods high in saturated fats. Indirect evidence suggests that such a causal relationship is plausible, though it remains to be demonstrated by rigorous studies in community settings. The evidence includes a large longitudinal study conducted in China – under conditions substantially different than those in Europe – that found that increases in the prices of unhealthful foods were associated with decreased consumption of those foods. Another longitudinal study in the US found an association between differences in food prices and BMI of young children. These studies comprise indirect evidence for effects of price differences on food consumption or weight in large-scale community settings, but there are important limitations to the generalizability of their findings.

Modelling analyses drawing upon actual market data to track how food purchasing responds to changes in prices suggest that a combination of increased prices (in the form of taxes) for such nutrients as fat, saturated fat and sugar and subsidies on fibres could reduce consumption of the taxed nutrients as well as total energy intake. However, the findings of modelling studies do not comprise empirical evidence.

Studies of tax and price policies applied to tobacco and alcohol products in many countries provide persuasive evidence of their impact on decreasing consumption of those products. These policy interventions may serve as models for similar approaches for lowering consumption of highly saturated fats or other energy-dense foods. However, critical differences among these types of interventions may limit their generalizability to food consumption.

A small body of evidence indicates that reducing the price of fruits, vegetables and other healthy snacks at the point of purchase (vending machines, cafeterias) increases their consumption. Another small body of evidence that includes several RCTs shows that financial incentives may result in temporary weight change.

Considerations for policy and research

Evidence of food price elasticity (i.e., how much demand for food responds to changes in price) is limited. Food price inelasticity may dampen the effect of economic instruments, as many people – including those in the lower-income brackets – will neither reduce consumption of foods high in saturated fats at higher prices nor consume more healthful foods at lower prices. Any policies that raise prices of certain foods without complementary intervention, such as subsidies for healthful foods, may be viewed as inequitable.

Taxation and pricing policies have contributed to tobacco prevention and control. However, taxing and pricing policies for foods, most of which are not controlled substances or subjected to special restrictions for certain age groups, may be more difficult to implement. Tax revenues generated from the sale of foods high in saturated fats could be used to subsidize the cost of healthful foods or health promotion programmes. As in the instances of alcohol and tobacco control, the most effective approaches for preventing and managing the complex, multifactorial problem of obesity may involve a number of concurrent interventions.

Type of evidence used in this review

This synthesis is based on evidence from the main databases of biomedical and health economic literature through May 2006 as well as a small number of unpublished monographs of direct relevance to the synthesis question.