Fibroblast growth factor 21-inducing rare sugars prevent diet-induced obesity in male BL/6 mice

The consumption of a high-fat, high-sucrose diet (HFHSD) promotes obesity. Although dietary sugars are obesogenic, they activates a negative feedback mechanism between hepatic fibroblast growth factor 21 (FGF21) and oxytocin neurons in the paraventricular nucleus of the hypothalamus (PVH^Oxt), thereby suppressing sugar appetite. We previously reported that the low-calorie rare sugars d-allulose, d-tagatose, and d-sorbitol induce FGF21, activate PVH^Oxt neurons, and reduce sugar intake. In this study, we evaluated the anti-obesity effects of these rare sugars in male BL/6 mice. The mice were fed with HFHSD, along with ad libitum access to FGF21-inducing rare sugar solutions for 1 month. Body weight, feed intake, fluid intake, and total caloric intake were recorded every 3 days. At the end of the treatment, obesity-associated parameters-including insulin resistance, glucose intolerance, and adiposity-were assessed. Rare sugar supplementation reduced body weight gain and total caloric intake without increasing energy expenditure. These interventions improved obesity-associated phenotypes to varying degrees, suggesting that these rare sugars ameliorated the overall state of diet-induced obesity. In contrast, these sugars did not reverse established obesity or insulin resistance, as prolonged HFHSD feeding desensitized mice to their effects. Therefore, rare sugars appear effective for the prevention, but not the treatment, of diet-induced obesity.