The current study evaluates the effects of NKT cell deficiency on obesity, associated metabolic changes, and atherosclerosis in Jα18−/−Ldlr−/− (lacking iNKT cells) and Cd1d−/−Ldlr−/− (lacking invariant and type II NKT cells) mice, and control mice were fed an obesogenic diet (high fat, sucrose, cholesterol) for 16 weeks. The gene discussed is CD1D; the disease is obesity due to melanocortin 4 receptor deficiency.