Along the same line, the beneficial effects of long-chain polyunsaturated fatty acids n-3 (n-3 PUFA), especially eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) found in fish oil (FO), have been widely demonstrated in improving dyslipidemia, glucose tolerance, insulin sensitivity, and reducing adipose mass in HFD-induced obesity models [10,11,12,13]. The gene discussed is INS; the disease is obesity due to melanocortin 4 receptor deficiency.