Illustration: Xia Qing/GT

Chinese scientists have found the gene that helps protect people in southern China and Southeast Asia against obesity, shedding more light on a potential solution to a growing global problem.

Obesity is a global health issue caused by abnormal or excessive accumulation of fat. Mitochondria play the role of an energy factory in human bodies, and the respiratory chain is responsible for producing 80-90 percent of the energy needed by the human body.

In addition, mitochondria play a crucial role in metabolism, especially in fat metabolism, throughout the life process. Genetic variations related to mitochondrial function may be associated with the occurrence of obesity.

Based on this theory, Associate Professor Zheng Hongxiang, Professor Jin Li and Professor Wang Jiucun from Fudan University conducted a research project along with other scholars that analyzed 2,877 samples from three independent populations in the southwestern region of Guangxi, the eastern province of Jiangsu and central China's Henan.

They found that a type of mitochondrial DNA known to be prevalent in southern China and Southeast Asia may acts as a protective factor against obesity.

Researchers at Fudan University examined the genetic makeup of 16 basal mitochondrial DNA haplogroups and discovered that a variant group known as M7 was consistently linked to a lower risk of obesity. Further investigation pinpointed a specific subgroup, M7b1a1, as the primary contributor to this protective effect.

The M7b1a1 lineage is mainly distributed in southern China and Southeast Asia, with a frequency of about 5-14 percent in the Han ethnic group in China, Zheng told the Global Times in an interview.

He said that evolutionary analysis has shown that this lineage experienced a rapid expansion in the population around 15,000 years ago, making it an important mitochondrial DNA expansion in the Chinese population.

This study was published in the peer-reviewed Journal of Genetics and Genomics last month.

Scientists said that previous epidemiological studies suggest that the obesity rate is relatively low in East Asian populations, including Chinese, Japanese, and Korean populations, while the obesity rate is generally higher in the Americas, the Pacific region, and the Mediterranean region.

A study published in the Lancet reported previously that in China, the obesity rate increased from 2.0 percent in 1990 to 7.8 percent in 2022 for women and from 0.8 percent to 8.9 percent for men. The prevalence of obesity in China ranked 11th lowest (190th highest) in the world for women and 52nd lowest (149th highest) in the world for men in 2022.

However, obesity is becoming a more and more concerning problem in China.

Zhang Zhongtao, deputy dean of Beijing Friendship Hospital affiliated to Capital Medical University, pointed out at a 2023 conference that obesity creates a huge burden in terms of disease and on the economy globally and has become a major public health problem in China. It is estimated that by 2030, China's health expenditure related to obesity will account for about 22 percent of the total national medical expenditure.

"The number of patients in China undergoing weight loss and metabolic surgery reached 10,000 in three years from 2018 to 2021, but to get to 20,000 took only one year, from 2021 to 2022," Zhang said. There are two main challenges facing the development of weight loss and metabolic surgery in China, which are how to promote the expansion of high-quality medical resources and balanced regional development, and how to improve clinical specialty diagnosis and treatment capabilities and the safety level, Zhang noted.

Obesity is a complex disease with multiple factors, including genes and environmental factors, said Zheng, noting that he believes that mitochondrial DNA genotypes may contribute to the risk of obesity, but it may not be the main contributor.

Zheng opined that his study is still basic research, and there is still a certain distance from clinical research. Yet he said this study offers insights into the genetic factors underlying obesity and potential treatment measures for the future.