Genetic ablation of UCP1 may not influence the IL-25–mediated anti-obesity effect because IL-25 reduced body weight gain (S3I Fig) and eWAT mass (S3J Fig), lowered liver mass (S3K Fig) in obese UCP1+/+ as effectively as in obese UCP1−/− mice. The gene discussed is UCP1; the disease is obesity due to melanocortin 4 receptor deficiency.