LONDON (Reuters) – Taxing junk food, limiting food adverts and making labels clearer could be the best way to curb rising obesity levels in countries like India and China, where increasing prosperity is creating ever heavier consumers.

The average annual cost of tackling obesity with these measures could be less than $1 per head, and global experts said in a study that emerging economies should take immediate action to reverse rising obesity rates before the problem reaches levels seen in the industrialised world.

Researchers from the World Health Organisation (WHO) and the Organisation for Economic Cooperation and Development (OECD) studied possible strategies to combat obesity in six emerging economies and also in England.

They found that combining prevention steps into a co-ordinated strategy would have a significant health impact.

"A multiple intervention strategy would achieve substantially larger health gains than individual programmes, with better cost-effectiveness," said Michele Cecchini, an OECD health policy analyst and one of the authors of the study.

The study, published in the Lancet, found unhealthy diets and a lack of physical inactivity were pushing obesity rates in these seven nations rapidly towards the average of all OECD nations, where half of the population is already overweight and one in six people is obese.

The OECD said a combined strategy on preventing obesity could cost less than a dollar per person and would pay for itself – through reduced healthcare costs – in half the countries surveyed, and would become cost-effective in the others within 15 years.

In terms of greater health expectancy – the number of years people live without developing chronic illnesses – a combined strategy would add a million years across the population in India and four million in China in the next two decades, the researchers said.

A total of two million more years of good health would be added within two decades across Brazil, Mexico, Russia, South Africa and England.

Breaking down the costs for each country over the 20-year time frame, the study found the cost of gaining each year of healthy life would be $270 in India and $380 in China.

A coordinated strategy would include health promotion campaigns in mass media, taxes and subsidies to encourage people to eat healthier foods, compulsory food labelling and curbing advertising to children, the researchers, led by Franco Sassi of the OECD, said in the study.

Being overweight or obese raises the risk of heart disease, diabetes, some cancers and arthritis — all chronic diseases that require expensive and prolonged treatment.

According to the study, seven in 10 Mexican adults are overweight or obese. Nearly half of all Brazilians, Russians and South Africans are overweight or obese, and while China and India have lower levels of obesity, they are "rapidly moving in the wrong direction" it said.