On with the pennies, off with the pounds? The use of taxation policies in obesity prevention

Abstract

Kate Timmins, University of Leeds summarizes the evidence and issues surrounding food taxation as a preventative measure for obesity The Danish government caused controversy in 2010 when it introduced a 'fat tax' - a food tax based on fat content.1 Romania in the same year proposed a 'junk food tax'2 and both Australia and Canada have launched taxes on sugarsweetened beverages.3 The idea of the 'sin tax' is not new. Fiscal policies have been exploited widely to combat rates of alcohol and tobacco use and have been acclaimed for their effectiveness.3,4 Governments have also welcomed such strategies for their revenue-making potential. Stemming the rising rate of obesity is in our interest. With many associated adverse health outcomes, the costs to healthcare are set to rise. The idea behind taxation policies lies in the theory that cost of diet contributes to the 'obesogenic' environment. Food price trends appear to have been less favourable for energy-dilute foods such as fruits and vegetables, than for energy-dense foods such as soft drinks or oils.6 This is bolstered by evidence of an inverse relationship between the energy density of a food and its price per unit of energy.7,8 In addition, observational evidence suggests that people who consume healthier9 or more energy-dilute diets8 tend to have higher food expenditures. The discussion of pricing effects also clearly needs to draw upon theories of consumer behaviour. The apparently 'irrational' decision to overeat can be explained by a number of considerations, one of which may be a bias towards present rather than future outcomes.10 The manipulation of food prices could change the decision-making environment, perhaps by increasing the costs pertinent to the present.11 Already, guidance suggests a role for pricing strategies in chronic disease prevention.12 Despite little direct evidence of an effect of calorie cost on weight status, a small body of evidence has examined the consequences of price reductions on the purchase of healthier foods. An intervention in schools found that varying discounts on lower-fat vending machine snacks elicited proportionate improvements in sales.13 The Supermarket Healthy Options Project (SHOP)14 was a large, randomized trial in a New Zealand supermarket. In the intervention group, a 12.5% discount was applied to foods classified as healthy. While this led to a significant increase in the purchase of healthy foods at six months (10%-11%), no observable effect was noted on any of the nutritional outcomes measured. In the laboratory, a study of hypothetical meal selections15 showed that the price increase of high-calorie foods did lead to a decreased demand for calories, but only when participants had no explicit calorie information. Such evidence is suggestive of an effect, although it does not address the potential relationship with bodyweight. Understandably, given its recent implementation in Denmark and Romania, there are no studies yet as to the effectiveness of taxation as a policy for obesity prevention. Conclusions must be extrapolated from observations of trends in price, purchasing and bodyweight, or from modelling studies based on such data. Inferences derived from other healthcare arenas where fiscal measures have proved a success, such as tobacco control, are inappropriate for food, a basic consumption good.16 A review of the literature concerning economic instruments in curtailing food consumption17 concluded that, although findings were suggestive, the evidence was tenuous and an effect could not be established. Dietary surveys conducted after changes in food subsidies and taxes in China suggested that price increases led to decreased intake of that food and increased consumption of substitutes, with observable effects on macronutrient intake.18 Furthermore, studies suggest a link between adolescent BMI and fast food or fruit and vegetable prices by area.19 However, national-level studies in the USA suggest time trends in food prices and obesity do not correspond. …