Obesity is becoming more common, even in rural China
More than 25% of adults in China are now considered overweight or obese, according to new research.
The findings, in the journal Health Affairs, blame declining physical activity and a more Western diet.
The report warns that obesity rates will double by 2028 if the Chinese government fails to take action.
Researchers say what is happening in China could be seen as a marker for what is going to happen in the rest of the developing world.
Poverty and obesity link
Since China's rapid economic changes began, the proportion of overweight and obese people has grown steadily.
This latest study, authored by Professor Barry Popkin, assessed 20,000 people across the country and has worrying health implications.
The report found that rates of hypertension and diabetes are rising rapidly.
Already about four out of every five deaths in China are due to non-communicable diseases - conditions like heart disease and cancer. An unhealthy diet and weight can be contributing factors.
According to the BBC's Asia analyst, Jill McGivering, obesity has often been associated with China's new affluence and urban, more Westernised lifestyles.
But this survey suggests that low income people in rural areas are now more likely to be overweight than those on higher incomes in the cities.
That mirrors the situation in the developed world, where poverty and obesity are often related.
Prof Popkin told the BBC that China's traditional balanced diet was increasingly giving way to one high in oil and meat.
And correspondents say that even in the countryside, people are getting much less exercise. Agriculture is more mechanised, and cars, motorbikes and tractors are replacing bicycles.
People are also watching much more television.
The Chinese government is aware of the health problems being stored up - but so far it is being criticised for failing to put much emphasis on promoting the need for a healthy weight.