Fig. 1: The susceptibility of middle-aged mice to obesity is attributed to altered WAT function.

a Body weight gain of young (3-month-old) and middle-aged (12-month-old) mice fed with a 4-week high-fat diet (HFD) (n = 14 per group). b, c Glucose tolerance test (GTT) (b) and insulin tolerance test (ITT) (c) results of young and middle-aged mice challenged with a 4-week HFD (n = 14 per group). d Flow cytometry analysis of the proportions of M1 (CD11b⁺/F4/80⁺/CD11c⁺/CD206^-) and M2 (CD11b⁺/F4/80⁺/CD11c^-/CD206⁺) macrophages in the epididymal WAT of young and middle-aged mice (n = 8 biological replicates per group). e RT‒qPCR analysis of the mRNA expression of proinflammatory genes (Tnf-α, Il-1β, and Il-6) in the epididymal WAT of young and middle-aged mice challenged with a 4-week HFD (n = 8 biological replicates per group). f Number of differentially expressed genes (DEGs) in the liver, muscle and WAT of C57BL/6 mice of different ages (9, 12, and 15 months). g–i Western blot analysis of p-AKT^Ser473/AKT, p-ACC^Ser79/ACC, p-HSL^Ser660/HSL and PGC1α in WAT (g), p-AKT^Ser473/AKT, PGC1α, SDHB and NDUFS1 in skeletal muscle (h), p-AKT^Ser473/AKT, PEPCK, G6Pase and p-GSK3β^Ser9/GSK3β in liver (i) from young and middle-aged mice (n = 3 biological replicates per group). j-l Western blot analysis of p-ACC^Ser79/ACC, p-HSL^Ser660/HSL and PGC1α in subcutaneous WAT (j), PGC1α, SDHB and NDUFS1 in skeletal muscle (k), PEPCK, G6Pase and p-GSK3β^Ser9/GSK3β in liver (l) from young and middle-aged humans (n = 10 biological replicates per group). The data were presented as mean ± SEM. Statistical significance was assessed by two-way ANOVA and Bonferroni’s multiple comparisons test (a, left panels in b, c) or a two-sided Student’s t test (right panels in b–e). See also Supplementary Fig. 1. Source data are provided as a Source Data file.