Unacylated ghrelin stimulates fatty acid oxidation to protect skeletal muscle against palmitate-induced impairment of insulin action in lean but not high-fat fed rats.

•Saturated lipids acutely impair muscle insulin signaling and glucose transport.•Ghrelin isoforms consistently protect insulin signaling from lipid detriment.•Unacylated ghrelin more potently stimulates fat oxidation, preserving glucose transport.•Muscle of chronic high fat-fed rats may be resistant to ghrelin’s metabolic effects.