Metabolic comparison of weight matched obese male and female mice

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Estrogen is a known regulator of body composition and insulin sensitivity. However, a reduction in body weight (BW) is commonly associated with the reported benefits of estrogen. The purpose of this study was to compare the metabolic health of obese male and female mice matched for BW. Male and female mice were fed a high fat diet until they achieved a BW where insulin resistance is typically observed (45 g). BW gain was much more rapid in male mice as it took 3.5 months to achieve this target BW (44 g) while it took 6 months for females to achieve a similar BW (46 g). Plasma estrogen concentrations were not different between obese (92.7 pg/mL) and age matched lean (92.5 pg/mL) female mice. Despite a similar final BW, obese females had significantly larger gonadal (3.7 vs 2.2 g) and subcutaneous (3.3 vs 2.3 g) fat pads as compared to obese males. Glucose area under the curve following a glucose tolerance test was significantly improved in obese female mice as compared to obese male mice. Improved glucose tolerance was associated with reduced gonadal fat gene expression of CD11c, MCP‐1 and IL‐6 with a trend for decreased IL‐1β. Overall, our data demonstrate that circulating concentrations of estrogen were not altered in obese female mice and when matched for BW, female mice displayed increased adipose tissue mass, reduced adipose tissue inflammation and improved glucose tolerance as compared to obese male mice.