Another paper in the series set out what we currently know about the emerging evidence on the effectiveness and cost-effectiveness of interventions for adults and children based on work from Australia. The good news is that 8 of the 20 interventions assessed were cost-saving. At the top of that list – and the intervention with by far the largest projected impact on health – was a 10 per cent tax on unhealthy foods and beverages.
Hungary and Denmark have both introduced so-called 'fat taxes' on certain products, which are being debated across the developed world. In response to the Danish tax, David Cameron said, 'Don't rule anything out, but let's look at the evidence'. Andy Burnham (speaking on Question Time) was less positive, ruling it out on the grounds that a tax would be regressive – penalising the poor, who spend a much higher percentage of their household budget on food.
This, of course, assumes that a tax wouldn't work well at changing what we buy. Whether this judgement is correct depends on many things: exactly how a tax is levied (for instance, on ingredients or products); how comprehensive it is; and what substitutes are available. This in turn depends on non-economic factors such as the ability to cook; the availability of substitutes in local food markets; time constraints; and, not least, social norms and culture. Relative prices between some foods could also be changed in other ways, including by reforming the Common Agricultural Policy. An alternative approach would be to consider subsidies for 'good' foods rather than taxes on 'bad' foods. For example, recent research has shown that eating particular foods, such as nuts, fruit and yoghurt are associated with the prevention of long-term weight gain.
Any intervention that changes prices could also have unintended consequences. In the United States, the tax debate has focused on carbonated drinks. But while modelling has shown that moderate tax increases would reduce calorie intake and raise revenue for public health programmes, this has been countered by others, who say that such a tax could distort behaviour with unfavourable effects, shifting consumption to close – and potentially problematic – substitutes, such as alcohol.
So, as the Lancet evidence paper itself makes clear, the science behind the effects of levying a fat tax are not clear cut. Deciding whether and how to change the relative prices of food and beverages that are associated with obesity requires much thought and analysis, not knee-jerk reactions for or against. So, what does the government's hot-off-the-press policy statement, Healthy Lives, Healthy People: A call to action on obesity in England, say about this thorny and important issue in its chapter on the evidence for obesity interventions?
Absolutely nothing. You will search in vain for any mention of taxes, subsidies or price as a potential lever in tackling obesity in England. It seems the Department of Health has ruled out fat taxes, even if the Prime Minister hasn't.
This blog also featured on the Guardian Healthcare Network