A new study published in ASN’s The Journal of Nutrition suggests that levels of a hormone called asprosin may predict weight changes in certain postmenopausal women.
Researchers found that women with higher asprosin levels at the start of the study gained less weight over the next three years. However, the findings show that the story is more complex than the number on the scale alone.
Funded by the National Institute of Health, the research was led by Dr. Simin Liu from the Center for Global Cardiometabolic Health and Nutrition and the Joe C. Wen School of Population & Public Health at the University of California, Irvine and draws on data from the Women’s Health Initiative (WHI), one of the largest and longest-running studies of women’s health in the United States.
What is asprosin?
Asprosin is a hormone made by fat tissue. It is released when the body is fasting, such as between meals or overnight. This hormone signals the liver to release glucose, or blood sugar, into the bloodstream so the body has energy. It also acts on the brain to help regulate appetite. Early studies in animals suggest that asprosin may influence hunger and metabolism, but its long-term role in weight regulation in humans is not well understood.
What did researchers study?
In this study, researchers analyzed data from more than 4,000 postmenopausal women, ages 50-79 at enrollment, and followed them for three years. They measured asprosin levels at the start of the study and then tracked changes in body weight and body composition.
All participants received weight-related measurements, including body mass index (BMI), waist circumference, waist-to-hip ratio, and waist-to-height ratio. In a smaller subset of women, researchers also measured body composition using dual energy X-ray absorptiometry, or DXA scan. A DXA scan uses very low dose X-rays to measure bone density, body fat, and lean mass, which includes muscle.
What did they find?
Among women who were not obese and did not develop diabetes during the study period, those with higher asprosin levels at the beginning of the study gained less weight over three years. They were also less likely to experience major weight gain and more likely to experience major weight loss.
These associations were not seen in women who developed diabetes during follow-up.
The difference is not just about the number on the scale
In the smaller group of women who had DXA scans, researchers found that women with higher asprosin levels gained less total weight. However, most of this difference reflected changes in body composition. These women tended to lose muscle, also called lean mass, while gaining body fat.
Muscle and fat are different kinds of tissue and affect health differently. Muscle is more compact than fat, even though both weigh the same. This means that a person can lose muscle and gain fat without seeing much change on the scale.
Even if overall weight gain seems modest, losing muscle and gaining fat can increase health risks.
Why this research matters
Weight gain and changes in body composition are common after menopause and can increase the risk of heart disease and type 2 diabetes. These findings suggest that asprosin may help identify which healthy postmenopausal women are more likely to experience certain patterns of weight and body composition change.
Researchers emphasize that more studies are needed. Future research should include repeated asprosin measurements, better tracking of physical activity and energy use, and larger study groups to better understand how asprosin affects weight regulation. This knowledge could help determine whether asprosin might one day serve as a target for preventing or treating obesity, a major risk factor for type 2 diabetes.
About the Women’s Health Initiative (WHI)
This research used data from the WHI, a landmark national study focused on major health issues affecting postmenopausal women. The WHI enrolled more than 160,000 women and has followed many of them for decades to study ways to prevent heart disease, cancer, and osteoporosis. Because of its size and long follow-up, the WHI provides a powerful resource for understanding how women’s health changes over time.
