Katherine Rich: Snake-oil theories won’t solve obesity problem

There’s not much doubt that New Zealand has an obesity problem. The OECD says Kiwis are the third-fattest people in the world. We’re also told the problem is growing, and that’s something that we as a country should be concerned about. 

But to turn this problem around we need to concentrate on what will work. We don’t need stupid ideas that are nothing more than modern-day snake-oil theories.  That’s what putting a tax on sugar is. 

The argument for such a tax is that by raising the price of goods containing sugar, people will switch to those with less or no sugar because they are cheaper and, hey presto, obesity levels will drop. But this argument is seriously flawed on several fronts. The most telling of these is that evidence shows sugar intake is not associated with body weight. 

That evidence comes from a highly respected source – Associate Professor Winsome Parnell and a team of nutritionists at the Department of Human Nutrition atOtagoUniversity. In 2008, they investigated the relationship between body mass index and intake of sugars and fat inNew Zealandadults and children by analysing data from the 1997 National Nutrition Survey for Adults and the 2002 Children’s Nutrition Survey. 

And what they found surprised many: “Sugars intake was significantly lower among obese compared to normal weight children. In adults and children, those with the lowest intake of sugars from foods were significantly more likely to be overweight/obese.” Their conclusion: “Current sugars or sucrose intake is not associated with body weight status in theNew Zealand population.” 

Someone wanting to take a cheap shot could dismiss these findings by pointing out that Parnell’s study was funded by the sugar industry (which it was). But consider this. This was an analysis of two surveys conducted by the university for the Ministry of Health. Those surveys helped assist the work of government and non-government organisations, and were used for forming development of food and nutrition polices and guidelines, such as the Ministry of Health’s Food and Nutrition Guidelines, and the Nutrient Reference Values for Australia and New Zealand. This was no biased research project asking leading questions, and there is no doubting Parnell’s brand as a public health expert. She and her team had absolutely nothing to gain from finding other than what was in front of them. 

The 2008/09 Adult Nutrition Survey, also conducted by the university for the ministry (and now on the ministry’s website) made an equally fascinating finding: sugar intake by males in the 11 years since the 1997 survey had dropped (there was no change in females) at the very same time there had been an increase in mean weight and body mass index, and an increase in the prevalence of obesity in both sexes. Compelling stuff.

People who know far more about the science of this issue than I do, say obesity is not a sugar-intake issue – it’s a fat-intake issue. And a lot of public health activists gloss over that, or simply don’t (want to) understand the link when discussing sugar or the genuine drivers of obesity. 

Outspoken Auckland GP Jim McVeagh has plenty to say on this: “Apart from the very few people who have some serious metabolic disorder, all that causes obesity is taking in more calories than you burn up. If you exercise and eat fewer calories, you will always lose weight in the long run.” He says humans are “wired” to like the taste of fats and carbohydrates because they are the high-calorie foods we need to survive. He points out that potatoes, white bread, rice, and pasta become sugar in the body as fast as pure cane sugar. “Taxing sugar is like sticking your finger in the dyke when the tsunami alarm has just gone off”.  He points out some difficult conundrums, asking that if we tax sugar, should we not also tax other foods which either produce sugar in the body or which have natural sugars in them. As examples he points to honey, which is 80% sugar, tomato sauce (16%), fruit juice (10%), milk (4%), bread (2%). 

So, while two comprehensive studies on New Zealand (rather than overseas) consumption habits debunk the ‘sugar causes obesity’ claim, those who call for a tax on sugar would clearly be happy to see the price of many foods, including staple foods and fruit juices, rise. And we know who loses out if that happens – New Zealand families, many of whom are already struggling to pay their bill at the checkout.

If, after all this, you still believe sugar causes obesity and that a tax is the best solution to the problem, consider the findings of British nutrition expert Professor Jack Winkler. He estimates that a 10% tax on sugar-sweetened beverages could lead to a consumption decrease of 7.5ml per capita per day. “In plain English, 7.5ml is 0.4% of the most popular two-litre bottle, less than a sip. It would not even cut sugar intake by a gram …” 

Over the past six months there have been calls for fat taxes, salt regulation, and sugar taxes. These are all blunt attempts to get New Zealanders to embrace healthier lifestyles, and though the Government would generate significant tax revenue from them, it’s very unlikely such taxes would change habits.

Calls for a tax are an unnecessary attack on sugar, which should actually be part of a healthy, nutritional diet. This is simply more of the same from a public health lobby keen to demonise a number of food ingredients to no obvious advantage, and probably serious disadvantage, for consumers.  All a tax would achieve is make nearly all food more expensive for families who are already struggling with their grocery bill, possibly even putting the health of children and the elderly at risk. It would not improve our health, it would just penalise moderate consumption. 

It all sounds like a good case for a balanced diet and a little more exercise. We have much progress to make, but demonising sugar is not the answer.