A new Chinese study has found that obesity can significantly damage brain health, with some obese adults experiencing a decline in brain volume equivalent to 12 years of aging.

For the study, researchers from Beijing’s Tsinghua University and Capital Medical University Affiliated Beijing Friendship Hospital tracked the body mass index (BMI) and brain health of more than 1,000 Chinese adults of varying ages for 16 years.

The results — based on neuroimaging data — showed a clear link between obesity and a number of indicators of cognitive decline, including reduced brain volume, increased white matter lesions, and abnormal microstructural integrity.

In China, a person with a BMI over 24 is considered overweight, while the threshold for obesity is 28.

According to the study, which was published in the open access science journal Health Data Science, an adult under 45 years of age with a BMI exceeding 26.2 experiences a decline in brain volume equivalent to 12 years of aging on average.

The state-owned media outlet Life Times reported on the study on Monday, highlighting the researchers’ conclusion that young people should try to keep their BMI below 26.2 to protect their brain health. “There is no healthy overweight person,” it added.

The Chinese study is not the only one to find a link between obesity and a decline in brain health. In 2023, a sub-journal owned by the Lancet published the results of a study that also showed a clear link between obesity and cognitive aging.

That study, based on an analysis of 10,000 people across Asia, found that for the average person, a 0.27-kilogram increase in visceral fat is equivalent to 0.7 years of cognitive aging.

The authors of the study suggest that Asia-Pacific is likely to experience even more cases of dementia as the region’s population ages and obesity levels rise. Currently, around 4 million people in Asia-Pacific develop dementia each year, accounting for 40% of new cases worldwide. Meanwhile, the obesity rate in Asia-Pacific is about 7% higher than the global average.

China’s obesity rate has also been rising rapidly in recent years. A study published in 2023, which involved nearly 15.8 million adults in over 240 different Chinese cities, found that 34.8% of participants were overweight and 14.1% were obese.

Men were more likely to be overweight and obese than women, and overweight individuals were more likely to experience a range of health problems, including fatty livers, prediabetes, and hypertension, the study found.

Sun Dejin, a neurologist from Shenzhen Third People’s Hospital, told Life Times that obesity leads to cognitive impairment, which if left unaddressed can have serious consequences for overall health and well-being.

“It manifests as poor thinking, learning, and memory functions — in other words, cognitive decline,” Sun said. “As the condition progresses, dementia may also occur.”

(Header image: VCG)