High-Protein Diet Combined With Lactobacillus acidophilus Improves Weight Loss, Lipid Metabolism, and Gut Microbiota in Obese Rats.

This study evaluated whether Lactobacillus acidophilus supplementation provides additional benefits to a whey protein-based high-protein diet (HPD) in diet-induced obese rats. After obesity induction, 48 male Wistar rats were assigned to four 12-week interventions (n = 12/group): ND1 (140 g/kg whey protein isolate), ND2 (ND1 + L. acidophilus), HPD1 (500 g/kg whey protein isolate) and HPD2 (HPD1 + L. acidophilus). Supplemented groups received 5 × 108 CFU/rat/day by oral gavage. Food intake, body-weight change, regional fat mass, serum biochemical markers and gut microbiota composition were evaluated. HPD-fed rats showed lower food intake, sustained body-weight loss and reduced visceral and epididymal fat masses compared with rats receiving normal-protein diets. Body-weight trajectories differed between dietary regimens (p = 0.013), whereas weight loss did not differ significantly between HPD1 and HPD2 (p = 0.06). Fasting glycemia remained unchanged. At month 3, ND1 showed the highest triglyceride and total cholesterol concentrations, while ND2, HPD1 and HPD2 displayed lower terminal values. High-protein feeding was associated with higher terminal urea and uric acid concentrations, whereas creatinine did not progressively increase. In the microbiota subset, HPD2 was characterized by higher relative abundances of Lactobacillus and Turicibacter. The whey protein-based HPD was the principal factor associated with body-weight reduction, lower adiposity and favorable lipid responses in obese rats. Under high-protein conditions, L. acidophilus did not confer an additional benefit for body weight or serum lipids, although its effect on gut microbiota composition warrants further functional investigation.