Swim training in diet-induced obesity did not affect body weight, subcutaneous fat mass or total fat mass (i.e., the weight of all dissected fat depots) but significantly attenuated weight gain during the 4-week intervention period (HFD: 78.6 ± 5.3 vs. Ex: 52 ± 7.7g, p = 0.03; Figures 1A–C, E) without effect on serum insulin or metabolites (Figures 1J–O), hepatic weight or hepatic triglycerides (Figures 1P,Q) (Supplementary Data). Here, INS is linked to obesity due to melanocortin 4 receptor deficiency.