Why obese women might combat CVD, diabetes better than obese men

Overweight and obese women might face better odds against diabetes, insulin resistance and CVD than men, according to a rodent study out of York University in Toronto.

The study measured blood vessel growth in adipose tissue in male and female mice, focusing on the sex differences between abdominal fat in obese rodents, first author Martina Rudnicki and colleagues wrote in Frontiers in Physiology Oct. 23. The researchers said they focused on gender disparities in mice since in humans, women who gain weight tend to stay healthier than their male counterparts.

“Mounting evidence of clinically important sex-related differences in the development of obesity-driven disturbances is garnering research attention, particularly in light of the growing global public health burden of obesity,” Rudnicki et al. wrote. “Increase in body mass index (BMI) is strongly associated with the incidence of obesity complications in both sexes. 

"However, despite higher rates of obesity in women, men are diagnosed with obesity-related complications at lower BMI than women.”

Past research has also suggested female animals are more resistant to obesity-related metabolic disorders than males, but aside from the fact that women and men differ in their susceptibility to conditions like cardiovascular disease and diabetes, scientists know little about the biological mechanisms underlying those differences.

Rudnicki and her colleagues assessed age-matched male and female mice for 16 weeks, feeding them either a regular diet or one high in fat. Researchers measured the animals’ systemic glucose disposal and insulin sensitivity upon the study’s conclusion.

The team found that female mice on a high-fat diet gained less weight than males fed the same meals, but no sex differences were observed in serum lipid levels or muscle capillarization. High-fat-fed females also managed to retain their metabolic function of perigonadal white adipose tissue, but perhaps the most significant finding was that overweight female mice recorded more blood vessels in their adipose fat tissue than males.

Blood vessels in fat tissue are critical for keeping the tissue healthy, oxygenated and saturated with nutrients, the authors said. Female mice seemed to increase their number of blood vessels as they were fed a high-fat diet, but males didn’t.

“Our findings highlight that females on a high-fat diet have greater vascularity in perigonadal adipose tissue than male mice,” Rudnicki et al. said. “Moreover, we present several lines of evidence to support the perspective that increased adipose vasculature in females is associated with lower fat accumulation, increased adipose tissue browning, preserved adipose tissue functions, whole-body glucose metabolism and greater muscle insulin sensitivity.”

The authors said it’s important to understand the fundamental cellular processes that regulate the growth of blood vessels, since they can contribute to a person’s risk for potentially life-threatening diseases.

“Taken together, our findings provide novel evidence that visceral adipose tissue of female mice display greater levels of proangiogenic factors and vascularity than males in response to (a) high-fat diet,” they wrote.