“ILSI does not profess to have been perfect in our 40-year history,” the statement said. “Not surprisingly, there have been bumps along the way. This is why ILSI has analyzed best practices and has committed to ensuring scientific integrity in nutrition and food sector research.”

Coca-Cola said in a statement that it had also been changing the way it funded scientific research through greater transparency and by ending its practice of providing the lion’s share of money for studies. In recent years, it added, Coca-Cola has sought to address mounting obesity in China by offering an array of new sugar-free beverages and through improved nutrition labeling on products. “We recognize that too much sugar isn’t good for anyone,” it said.

Professor Greenhalgh’s findings were based on interviews with Chinese officials and scientists, and a review of public documents produced by Coca-Cola and ILSI.

She said the industry efforts have been wildly successful, in part because China lacks a free media or watchdog organizations that might have been critical of the relationship.

In just a few decades, China has gone from a nation plagued by food shortages to one buffeted by soaring obesity and chronic diseases tied to poor diet. More than 42 percent of adults in China are overweight or obese, according to Chinese researchers, more than double the rate in 1991. In Chinese cities, nearly a fifth of all children are obese, according to government surveys.

The increases closely follow growing prosperity in China that began in the 1980s as Beijing embraced market economics after decades of isolation. In 1978, Coca-Cola was among the first companies allowed into the country, and ILSI arrived soon afterward. Seeking to identify influential scientists it could work with, the group found a partner in Chen Chunming, a leading nutritionist who was the founding president of the Chinese Academy of Preventive Medicine, the forerunner of China’s C.D.C.

In 1993, Ms. Chen became the head of ILSA-China and she remained a senior adviser to the organization until her death last year. Professors Greenhalgh and Popkin said that Ms. Chen was instrumental in stymying attempts to address soaring obesity by stressing the harmful impact of consuming highly processed food and sugary soft drinks.