A new study published in ASN Food magazine shows that levels of a hormone called asprosin can predict weight changes in some postmenopausal women.
The 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 suggest that the story is more complex than just the number on the scale.
The study, funded by the National Institutes of Health, was led by Dr. Simin Liu of the Center for Global Heart Health and Nutrition and the Joe C. Wen School of Population and Health at the University of California, Irvine, and was based 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.
Ask what?
Asprosin is a hormone produced by adipose tissue. It is released when the body is fasting, for example, between meals or overnight. This hormone signals the liver to release glucose, or blood sugar, into the bloodstream so the body can have energy. It also affects the brain to help regulate appetite. Early animal studies suggest that asprosine may affect hunger and metabolism, but its long-term role in weight regulation in humans is not well understood.
What did the researchers learn?
In this study, researchers analyzed data from more than 4,000 postmenopausal women aged 50-79 and followed them for three years. They measured asprosine 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 group of women, the researchers also measured body composition using dual-energy X-ray absorptiometry, or DXA scanning. A DXA scan uses very small x-rays to measure bone density, body fat, and lean mass, which includes muscle.
What did they find?
Among the women who were not obese during the study and did not develop diabetes, those who had high asprosine levels at the start of the study gained less weight over three years. They also felt less likely to gain weight and more likely to lose weight.
These associations were not observed in women with diabetes during follow-up.
The difference is not just about the number on the scale
In a smaller group of women who had DXA scans, the researchers found that women with higher asprosine levels gained less weight overall. However, most of this difference reflects changes in body composition. These women tend to lose muscle, also known as lean mass, while gaining body fat.
Muscle and fat are different types of tissue and affect health differently. Muscle is denser 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 the overall weight gain seems modest, muscle loss and fat gain can increase health risks.
Why is this research important?
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 asprosine may identify which healthy postmenopausal women are more likely to experience certain changes in weight and body composition.
The researchers stress that more research is needed. Future research should include repeated measurements of asprosine, better tracking of physical activity and energy use, and larger research groups to understand how asprosine affects weight regulation. This knowledge could determine whether asprosin could 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 study used data from the WHI, an important national survey focusing on major health issues affecting postmenopausal women. The WHI enrolled more than 160,000 women and followed many of them for decades, studying ways to prevent heart disease, cancer and osteoporosis. Because of its size and long follow-up, the WHI is a powerful resource for understanding how women’s health changes over time.
