Water Kefir and Olive Leaf Polyphenols Attenuate Body Weight Gain and Excessive Adiposity in Diet-Induced Obese Rats

Fermented foods and prebiotics are increasingly studied for their potential therapeutic roles in metabolic disorders. In this study, 52 male Wistar rats maintained on a high-fat, high-sucrose (HFS) diet were supplemented for 8 weeks with either water kefir (providing approximately 105 CFU per rat per day), olive leaf polyphenols (equivalent to 1.6 mg oleuropein daily), or a combination of both. Both interventions ameliorated HFS-diet induced weight gain, accompanied by reductions in subcutaneous and mesenteric fat, without additive effects when combined. Moreover, olive polyphenols decreased liver weight, suggesting a potential protective effect against hepatic steatosis through Fasn modulation. These metabolic improvements were accompanied by enhanced gut microbiota diversity. Together, these findings highlight water kefir and olive leaf polyphenols as potential dietary strategies for the management of obesity, hepatic steatosis, and dyslipidemia.