Allicin ↓ weight of obese mice, metabolic indicators, CORST, IR, and corrected HFD-triggered aberrant insulin signalling. HFD induced DLB, which was ameliorated by allicin.↑ ROS, MDA, protein carbonylation triggered by HFD were inhibited by allicin. HFD caused ↑ protein expression of autophagy in the Hippoc, which was reverted by allicin. Allicin ameliorated OS-induced damage through ↑ antioxidant SOD, CAT, GSH, and GPx activity. The gene discussed is INS; the disease is Lewy body dementia.