More people in the US are exercising, but obesity levels are still rising, according to new research from the Institute for Health Metrics and Evaluation (IHME) at the University of Washington.

Two studies undertaken by the IHME and published on 10 July 2013 in open-access peer-reviewed journal Population Health Metrics found that as physical activity increased in the US between 2001 and 2009, so did the percentage of the population considered obese. The study’s authors said obesity and risk factors from poor diets, smoking and high blood pressure are all causing a drag on US life expectancies, which increased slowly compared to the country’s economic peers between 1985 and 2010.

“More aggressive strategies to prevent and control obesity are needed. Diet and changes in individual behaviour are key components,” said Dr Ali Mokdad, Professor of Global Health at IHME and a coauthor of both studies. “Understanding local trends in obesity and physical activity in both rural and urban areas will help communities develop successful strategies and learn from one another,” he said.

The IHME said two other studies it published in July 2013 showed that because of the increase in obesity over the last two decades, high body mass index (BMI) is now the third-leading risk factor to health in the US.

Changes in ‘food environment’ necessary, says Australian expert

The research shows that food supply is the “primary driver” of the US obesity ‘epidemic’, according to Australian health expert Bruce Neal, Professor of Medicine at the University of Sydney and Senior Director at the George Institute for Global Health.

“The most likely explanation for this finding is that the rise in average physical activity levels has been outstripped by the excess of energy provided by the food supply,” Professor Neal wrote in a commentary piece published in Population Health Metrics.

“So while physical activity will benefit the health of the population even if it is not accompanied by weight loss, physical activity will not address most of the burden of ill health caused by obesity. That is going to require a new focus on the root cause of the problem – the American diet,” Professor Neal said.

“Diet must be the new target and will require an approach that prioritises renovation of the food environment above personal responsibility and individual behaviour change,” Professor Neal said.

Multifaceted approach needed

Professor Neal said that a ‘multifaceted approach’ is needed that addresses both the average composition of foods available and how are they marketed.

According to Professor Neal, foods should be reformulated to contain lower levels of salt, fat and sugar, and should be sold in smaller, “less energy-dense” servings. He also said marketing strategies “must be controlled to better protect children”, that portion sizes should be standardised, and that easy-to-understand mandatory front-of-pack labelling were necessary to address the issue.

Both Australia and the UK have recently introduced voluntary front-of-pack labelling systems, to mixed reception.

“Policy makers must also commence work on pricing strategies that subsidise the cost of healthier foods, develop standards that define the need for warning labels on the least healthy products, and take actions to ameliorate the impact of upstream factors such as agricultural subsidies and trade agreements,” Professor Neal said. “Industry can be a part of the solution to diet-related ill health but is too conflicted to contribute to policy development and should be engaged solely as the implementation partner,” he said.

Professor Neal is not the first to suggest subsidisation of ‘healthier’ foods. Australian Food News reported in April 2013 that a scheme in South Africa that offered a health insurance rebate for ‘healthier’ supermarket foods such as fruit and vegetables saw consumption of those foods increase. A similar scheme was started in October 2012 in the US by supermarket group Walmart.

“As unpalatable as this may be, the food industry would do well to strengthen their public health conscience, given that consumers are always going to need their goods,” Professor Neal concluded.

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