Almost twice as many obese people in poor countries than in rich ones as fat and sugar consumption rises, warns ODI

The extent of the world's obesity epidemic has been thrown into stark relief as a report from the Overseas Development Institute (ODI) puts the number of overweight and obese adults in developing countries at more than 900 million.

Future Diets, an analysis of public data about what the world eats, says there are almost twice as many obese people in poor countries as in rich ones. In 2008, the figures were 904 million in developing countries, where most of the world's people live, compared with 557 million in industrialised nations.

"The growing rates of overweight and obesity in developing countries are alarming," said the report's author, ODI research fellow Steve Wiggins. "On current trends, globally, we will see a huge increase in the number of people suffering certain types of cancer, diabetes, strokes and heart attacks, putting an enormous burden on public healthcare systems."

The report warns that governments are not doing enough to tackle the growing crisis, partly due to politicians' reluctance to interfere at the dinner table, the powerful influence of farming and food lobbies and a large gap in public awareness of what constitutes a healthy diet.

According to the report, overweight and obesity rates since 1980 have almost doubled in China and Mexico, and risen by a third in South Africa, which now has a higher rate than the UK. Regionally, north Africa, the Middle East and Latin America all have overweight and obese rates on a par with Europe.

Workers install lights on a giant McDonald's sign in Beijing. Diets in China are proportionally richer in animal products than in the 1960s. Photograph: AP

"The evidence is well established: obesity, together with the excessive consumption of fat and salt, is linked to the rising global incidence of non-communicable diseases, including some cancers, diabetes, heart disease and stroke," says the report. "What has changed is that the majority of people who are overweight or obese today can be found in the developing rather than the developed world."

The report highlights a paradox in the developing world. As well as obesity, under-consumption remains a problem for hundreds of millions of people in poor countries, where progress on reducing stunting – low height to age – has been slow. Up to a third of infants in the developing world are stunted.

Factors behind the increase in obesity include rising incomes and urbanisation, which tend to lead to diets rich in animal produce, fat, salt and sugar; and the various influences of globalisation, among them advertising and the media, on diets. But the report cautions against jumping to conclusions that national diets are converging on a single international norm.

In China, for example, diets, are proportionally richer in animal products and vegetables than in the 1960s, but sugar consumption remains low. In contrast, Thailand has experienced an increase in the per-head consumption of starchy roots and pulses as well as fruit, which Thais consume more than animal products.

This variety in diets carries certain implications, the report argues. Globalisation will not – in the medium term – place massive restrictions on the scope for policy action, and policy needs to start where people are, in terms of their preferences and traditions. "Trajectories are not preordained; there is scope to influence the evolution of diet to get better outcomes for health and agriculture," says the report.

Yet, Wiggins acknowledges that governments have been timid in staking out positions on diet. "Who wants to take on the food industry?" he said. "Then there is the moral and ethical dimension: people would not like the government to tell us what to put on the dinner table."

Thai villagers sell fruit at a floating market in Ratchaburi. Fruit consumption has risen in Thailand, the report says. Photograph: Apichart Weerawong/AP

This is not to conclude that diet policy must be timid, says the report, even if that is, apparently, the public mood. It contrasts government reluctance to act on diets with strong action to limit smoking. Although diet is a more diverse issue than smoking, says the report, there may be scope for governments to take more incremental measures that could pave the way for the public to accept something needs to be done if future health costs are to be contained.

Some governments have managed to change diets for the better. South Korea has increased fruit and vegetable consumption through a publicity, social marketing and education campaign, including training of women to prepare traditional low-fat, high-vegetable meals. Denmark banned trans fats, which have made its McDonald's among the healthiest in the world. Further back, the introduction of rationing in the UK during the second world war ensured that the poorest people were able to eat a balanced diet.

But these are the exceptions. For the most part, diets are increasingly unhealthy – with an increase in the consumption of sugar. Sugar and sweetener consumption has risen worldwide by more than a fifth per person from 1961 to 2009.

Less than a third of countries are consuming less than the recommended top limit of 50g of sugar a day per person, and 69 countries have average per capita sugar consumption of more than double this recommended upper limit. The world's top sugar consumers include the US, Belgium, the Netherlands, New Zealand, Costa Rica and Mexico.

Fat consumption remains a concern. Among developing countries the highest consumption of fat is in east Asia and southern Africa. However, industrialised countries still have much higher levels of fat consumption – often more than double their developing counterparts.