Intermittent fasting (IF) is a safe and sustainable approach for obesity treatment, yet its weight loss efficacy is relatively modest compared with that of pharmacologic anti-obesity therapies. The synergistic benefits of pairing IF with administration of nutrient-derived metabolites remain poorly understood. Here we report that combining IF with threonic acid (TA), an ascorbic acid metabolite, led to more pronounced reductions in body weight and food intake, as well as improvements in energy expenditure and glycemic control, compared with either intervention alone in diet-induced obese mice. These metabolic benefits were associated with the anorexigenic role of TA in reversing fasting-induced upregulation of the hypothalamic orexigenic neuropeptides NPY and AGRP. In the hypothalamus, TA competed with glucose for uptake via glucose transporter 3 (GLUT3), while IF boosted the TA uptake through both glucose depletion and upregulation of GLUT3, resulting in a more robust suppression of NPY and AGRP expression. Collectively, our findings highlight the combination of TA with IF as a promising metabolite-based combinatorial strategy to enhance the therapeutic efficacy of obesity treatment.