Medical and psychological harms of obesity depend on where you live, study indicates

The findings are published in Psychological Science, a journal of the Association for Psychological Science.

Researchers led by Jana Berkessel of the University of Mannheim in Germany collected archival data on more than 3.4 million people living in the United States and United Kingdom. They found evidence that obesity tends to spur lighter medical and psychological harms when those who struggle with the disorder feel less conspicuous.

"For me, this means that at least some of the adverse consequences of obesity appear socially constructed and, thus, can be reduced," Berkessel said.

The personal and societal toll of obesity is far-reaching. According to the World Health Organization, the global prevalence of obesity nearly tripled between 1975 and 2021. In the U.S. alone, health care costs related to obesity total roughly $147 billion, according to government figures. Research shows that compared with people without obesity, individuals living with obesity have higher unemployment rates, fewer friends, and poorer physical and mental health. They also face prejudice and discrimination.

But obesity rates vary between countries, states, provinces, and other regional divisions. In some parts of the U.S., roughly half of the population lives with obesity, while obesity rates in other regions are as low as 5%.

Berkessel and her colleagues theorized that the harsh effects of obesity vary based on the prevalence of obesity in a given region.

"It is quite easily imaginable that persons with obesity in regions with low obesity rates stick out much more, and therefore will have very different social experiences on an everyday basis," said Berkessel, who studies the effects of social context on our well-being.

The researchers examined three large datasets of people living in thousands of U.S. counties and hundreds of U.K. districts. Those data included information on participants' weight, height, and area of residence, as well as social, health, and economic outcomes. They used a Body Mass Index (BMI) of 30 or higher as a marker of obesity. (Medical professionals consider a healthy BMI to range from 18.5 to 24.9).

In one U.S. dataset, the researchers found obesity rates to be above average in the Midwest, the South, and along parts of the East Coast, and below average in New England, Florida, and the Western states. In a U.K. dataset, they found high obesity rates in Central and Northern parts of the country, particularly in Southern Wales. The lowest rates were found in the nation's southern region, including London.

Berkessel and her team found that, overall, participants with obesity reported more relationship, economic, and health disadvantages compared with participants without obesity. But they also found that those living in low-obesity regions were significantly more likely to be unemployed -- and to report suboptimal health compared to their counterparts in high-obesity areas.

The research team also examined U.S. data that included participants' self-reported attitudes toward people's weight. They found that weight bias seems to be lowest in areas with high rates of obesity, which might explain why people with obesity in those areas are less likely to be single and report poor health compared to those in areas with high weight bias.

Regardless of the regional differences around weight bias, public health experts should emphasize the importance of reducing obesity because of its health risks, the researchers concluded.

Berkessel's co-authors included Jochen E. Gebauer of University of Mannheim and the University of Copenhagen, Tobias Ebert of the University of St. Gallen, and Peter J. Rentfrow of the University of Cambridge.