Developing countries should act now to head off their own "obesity epidemic", says a global policy group.
The Organisation for Economic Co-operation and Development (OECD) says obesity levels are rising fast.
In a report in the Lancet medical journal, it says low-income countries cannot cope with the health consequences of wide scale obesity.
Rates in Brazil and South Africa already outstrip the OECD average.
Increasing obesity in industrialised countries such as the UK and US has brought with it rises in heart disease, cancer and diabetes.
However, increasing prosperity in some developing countries has led to a rise in "Western" lifestyles.
Now the OECD warns that they are catching up fast in terms of obesity rates.
Across all the countries represented in the OECD, 50% of adults are overweight or obese.
Rates in the Russian Federation are only just below this, and while fewer than 20% of Indians are classed this way, and fewer than 30% of Chinese people, the body says things are worsening fast.
The report recommends that these countries act now to slow the increase, with media campaigns promoting healthier lifestyles, taxes and subsidies to improve diets, tighter government regulation of food labelling and restrictions on food advertising.
Its authors calculate that doing this would add one million years of "life in good health" to India's population, and four million to China over the next 20 years.
The cost would be considerable but the OECD insists that the strategy would pay for itself in terms of reduced health care costs, becoming cost-effective at worst within 15 years.
Michele Cecchini, one of the report's authors, said: "A multiple intervention strategy would achieve substantially larger health gains than individual programmes, with better cost-effectiveness."
She suggested that specific action be taken to target childhood obesity.