Obesity‐induced insulin resistance was ameliorated in 7E‐treated mice. Male C57BL/6 mice were randomly assigned to the LFD (10% kcal derived from fat) or the HFD (60% kcal derived from fat) group for 16 weeks. The experiments began 1 week after HFD and the mice were divided into three groups (n = 10 mice per group): HFD mice without treatment, and HFD mice treated with 10 mg mIgG/kg/3 d, or 10 mg 7E/kg/3 d. (a‐b) Body weight and food intake were measured weekly. (c) A glucose tolerance test (GTT) and (d) an insulin tolerance test (ITT) were performed at week 15 after mIgG or 7E treatment. The fat pad weight (g), serum IL‐20 (e), leptin (f), triglyceride (h), ALT (i) and AST (j) levels of mIgG‐ and 7E‐treated HFD mice were measured. (k) The expression of IL‐20 in different organs and adipose tissue of mIgG‐ and 7E‐treated HFD mice was analysed using RT‐qPCR. Data are expressed as mean ±SEM and are representative of three independent experiments. *p < 0·05 compared with mIgG‐treated HFD mice