The claim

“We… reject the idea that a tax on soft drinks, which contribute just 2 per cent of the total calories in the average diet, is going to address a problem which is about overall diet and levels of activity.”
Gavin Partington, director general, British Soft Drinks Association, 18 February 2013

The background

The Academy of Medical Royal Colleges (AoMRC) weighed into the debate on obesity today.

The umbrella organisation representing the medical profession is making 10 recommendations to help Britain slim down, including an extra £100m of government investment, new standards for hospital food and new rules to curb fast food outlets near schools.

But the idea that has generated the most headlines is a 20 per cent tax on all sugary soft drinks, to be piloted for one year.

Predictably, the soft drinks industry isn’t keen.

The British Soft Drinks Association’s director general Gavin Partington said: “We share the recognition that obesity is a major public health priority but reject the idea that a tax on soft drinks, which contribute just 2 per cent of the total calories in the average diet, is going to address a problem which is about overall diet and levels of activity.

“Over the last 10 years, the consumption of soft drinks containing added sugar has fallen by 9 per cent while the incidence of obesity has been increasing, and 61 per cent of soft drinks now contain no added sugar.”

Will a new tariff on fizzy pop help us kick our Coke habit? And even if we do, how much are soft drinks to blame for the obesity boom.

“Soft drinks… contribute just 2 per cent of the total calories in the average diet.”

Here’s the evidence for this claim, from the National Diet and Nutrition Survey. It’s true that, across all men and women aged 19 to 64, only 2 per cent of total calories come from “soft drinks, not low calorie”.

It’s clear from the figures that young people, particularly teens, drink more sugary drinks than adults. For 11-18-year-old boys and girls, the amount of total energy intake from sweet soft drinks is 5 per cent, not 2 per cent.

To put that in perspective, non-alcoholic drinks are the second biggest source of carbohydrates for 11-18-year-olds. Teenage girls and boys are getting 10 per cent of their carbs from sweet soft drinks.

In any event, the amount of calories you get from these drinks may not be the most important factor.

Several US studies have found that soft drinks are associated with higher risk of obesity and related conditions like diabetes, and not just because they make you fatter.

One Harvard academic suggests that the high glycemic load – the way sweet drinks dump a lot of sugar into the bloodstream quickly and produce a spike in the hormone insulin – could be a bigger factor than the extra calories.

A major study on 33,000 people suggested that regular consumption of sugary beverages interferes with the genes that control weight gain, producing health risks that, again, could not be accounted for by overall calorie intake.

“Over the last 10 years, the consumption of soft drinks containing added sugar has fallen by 9 per cent while the incidence of obesity has been increasing, and 61 per cent of soft drinks now contain no added sugar.”

We haven’t been able to confirm that figure of 9 per cent, although released by the BSDA do suggest that slightly fewer sugary drinks have been sold in recent years, as low-calorie alternatives become more popular.

And if obesity is still going up, that must mean that it’s not the fault of the drink manufacturers, right?

Actually, obesity rates have levelled off since 2004 in this country, and there have been similar trends in other high-income countries.

One leading US researcher, Dr Michael Jacobson, has turned the manufacturers’ argument around by suggesting that one of the reasons for this is precisely because people are drinking slightly fewer sweet drinks.

Will a tax work?

The BSDA insists that it won’t, saying that consumers – and the poorest in particular – will continue to buy soft drinks even if the price goes up.

They point out that government figures show a 27 per cent rise in the price of soft drinks from 2007 to 2010, and consumption fell by only 3 per cent in that period.

True but misleading: the figures make it clear that the prices only began to rise in 2010, right at the end of the sample period, and probably too late for any effect on consumption to show up in these figures.

The question of price elasticity is key here: are soft drinks one of those items shoppers will leave out of the basket if the price goes up, or will they go on buying no matter what?

One US study found that a 10 per cent increase in soft drink prices would reduce consumption by 8 to 10 per cent. Another international study said the same price increase could cut consumption could be as high as 24 per cent.

Other economists have come up with much lower estimates and we’re not aware of any UK research that has settled the question.

The verdict

Nobody is saying that soft drinks are solely to blame for our expanding waistlines – not the doctors who authored today’s report, and certainly not us.

And let’s remember that the AoMRC is not saying a tax would definitely cut consumption – only that an experimental trial would settle the question of price elasticity.

It’s true that “sin taxes”, like a levy on high-fat food in Denmark, have failed, but that doesn’t mean a premium on sugary drinks will fail here.

And there is a growing body of evidence which says that trying to limit consumption of sugary drinks is a good place to start in the fight against obesity.

By Patrick Worrall