Insulin resistance (IR) underpins the relationship between obesity and its associated metabolic disorders. Negative energy balance alleviates IR rapidly, though the mechanism remains unclear. Here, we show that in obese mice, IR can be reversed by calorie reduction (CR) within a day. In the liver, improved insulin sensitivity correlates with reduced tri-(TAG) and diacylglycerol (DAG) concentrations and decreased protein kinase C epsilon (PKCε) activation. In muscle, insulin-stimulated glucose disposal was also restored, whereas obesity-related changes in adipose tissue largely persisted following CR. Specifically, obesity is associated with reduced fasting lipolytic activity in adipose tissue, likely mediated in part by lower beta-adrenergic receptor 3 (ADRB3) expression. Acute CR did not reverse these adipose changes but further reduced plasma free fatty acid (FA) levels by dampening lipolytic activity and upregulating oxidative pathways in muscle and liver. This facilitates insulin-stimulated glucose disposal and restores insulin sensitivity.