Green tea-mediated modulation of body weight gain: roles of sex, diet, and housing temperature.

Green tea (GT) is widely recognized for its metabolic effects, but the influence of biological sex and housing temperature on its response during diet-induced obesity remains incompletely understood. Male and female C57BL/6 mice were housed at standard temperature (22 °C) or thermoneutrality (28 °C), fed a standard diet (SD) or high-fat diet (HFD), and, after obesity induction, received GT by oral gavage at 500 mg/kg, five days per week, for 12 weeks. Longitudinal mixed-effects modeling and endpoint factorial ANCOVA showed that GT attenuated HFD-associated body weight gain in both sexes and at both housing temperatures. The significant Diet × GT interaction indicated that the effect on final body weight depended primarily on dietary condition, whereas no statistical evidence was found that the overall endpoint response differed according to sex or housing temperature. Plasma proteomic profiling of HFD + GT mice housed at 22 °C identified extensive remodeling in both sexes, with comparable numbers but distinct identities and directions of change among differentially abundant proteins. Candidate proteins were associated with lipid metabolism (APOC2 and ANXA2), inflammatory processes (CD68, CSF1, and SAA4), and neuroimmune-related functions (GRN), revealing distinct sex-dependent molecular patterns. Complementary hypothalamic immunohistochemistry showed that GT attenuated HFD-associated increases in GFAP and IBA1 immunoreactivity. The reduction in astrocytic GFAP immunoreactivity was particularly pronounced in males housed at 22 °C, whereas the decrease in microglial IBA1 immunoreactivity was broadly consistent across the comparisons evaluated. Together, these findings demonstrate that GT attenuates HFD-associated weight gain and hypothalamic glial immunoreactivity while inducing extensive, sex-dependent plasma proteome remodeling. These findings highlight dietary context as a major determinant of the physiological response to GT and identify biological sex and housing temperature as important variables shaping its molecular effects. SIGNIFICANCE: This study shows that green tea attenuates HFD-associated body weight gain and hypothalamic glial immunoreactivity while inducing sex- and temperature-sensitive plasma proteomic responses. By integrating physiological, proteomic, and histological analyses, we identified molecular- and tissue-level changes associated with lipid metabolism, inflammation, and glial reactivity. The findings indicate that dietary status is a major determinant of the physiological response to green tea, whereas sex and housing temperature shape the associated molecular signatures. These results emphasize the importance of experimental context in preclinical nutraceutical research and support further investigation of green tea-derived compounds in obesity-associated metabolic and neuroimmune alterations.