Sex and diet shape fat tissue lipid profiles in obesity

In obesity, adipose tissue expands and accumulates, driving chronic inflammation. Previous research showed that sex steroid hormones can influence adipose tissue distribution, accumulation and immune responses in men and women. Changes in lipid composition in the visceral or gonadal white adipose tissue, or GWAT, during obesity can drive immune cell accumulation and boost proinflammatory mediators. Prior studies revealed sex differences in GWAT lipid species in obese mice, but scientists still do not understand the exact role of sex hormones in lipid composition.

In a recent study in the Journal of Lipid Research, Mita Varghese and a team of researchers at the University of Michigan investigated the GWAT lipid profiles in obese mice and mice with their gonads surgically removed, or GX mice. In an untargeted lipidomics analysis where they comprehensively analyzed all lipids, they found sex differences in several lipid species, such as phospholipids and sphingolipids, which are important cell membrane components. Obese males had significantly more precursor fatty acids than females and GX mice. Targeted analysis revealed sex differences in polyunsaturated fatty acids, or PUFAs, with males showing a significantly higher omega-6 to omega-3 ratio. They also found diet-driven differences in oxylipins, inflammation-linked lipids, which were higher in both male and female obese mice than in lean mice.

This study suggests that sex hormone levels and diet equally induce inflammation and changes in lipid composition in obesity. Future studies include further confirming lipid profiles and understanding how sex differences arise in obesity.