COMPARATIVE EFFECTS OF VIABLE AND NON-VIABLE LACTICASEIBACILLUS RHAMNOSUS GG PREPARATIONS IN DIET-INDUCED OBESITY

Obesity is a multifactorial metabolic disorder associated with impaired glucose homeostasis and dyslipidemia. Probiotics and postbiotics have emerged as promising strategies to modulate metabolic dysfunctions associated with excess adiposity, while evidence comparing viable and non-viable preparations remains limited. This study evaluated the effects of probiotic and postbiotic preparations of Lacticaseibacillus rhamnosus GG on body weight, glucose tolerance, insulin sensitivity, and triglycerides in an obesity model. The study was approved by CEUA/UNICAMP (protocol 6118-1/2022). Forty 10-week-old male Wistar rats were assigned to four groups (n=10): Control, Model, Postbiotic, and Probiotic. The Control group received the AIN-93M diet, while the other groups received a modified high-fat diet. L. rhamnosus GG was administered as either a postbiotic or probiotic preparation (10⁷ n-AFU/g and 10⁷ AFU/g, respectively), resuspended in 2 mL of skim milk and administered via gavage. Glucose tolerance was expressed as the area under the curve (GTT AUC), and insulin sensitivity was assessed via KITT. Data were expressed as median (25th–75th percentiles) and analyzed using the Kruskal–Wallis test followed by Dunn’s test. Linear regression models including group and final weight were performed (p<0.05). Final weight did not differ among the groups (p=0.221), with medians of 453.2 (444.1–483.2), 485.4 (454.6–498.8), 486.3 (475.6–508.2), and 475.3 (453.6–527.0) g, respectively. GTT AUC differed among the groups (p=0.034), with medians of 769.3 (675.8–805.9), 894.0 (849.6–973.9), 878.5 (783.0–1013), and 855.5 (782.8–940.0), respectively; Dunn’s test identified a difference between the Control and Model groups (p=0.038, Holm-adjusted). KITT did not differ (p=0.642), with medians of 1.759 (1.242–2.250), 1.351 (0.9413–1.950), 1.504 (0.7086–1.925), and 1.514 (1.347–1.595), respectively. Triglyceride levels differed (p<0.001), with medians of 161.5 (151.8–180.3), 103.5 (75.50–120.0), 100.0 (88.00–101.0), and 135.0 (101.0–175.5) mg/dL; differences were observed between the Control and Model groups (p=0.004) and between the Control and Postbiotic groups (p=0.002). In the regression analysis, final weight showed an inverse association with KITT (β=−0.344, p=0.047) but not with GTT AUC (p=0.579) or triglycerides (p=0.177). The high-fat diet was associated with reduced glucose tolerance and alterations in triglyceride levels. Although supplementation did not significantly alter final weight or KITT, both supplemented groups showed a numerically lower GTT AUC compared to the Model group. Previous studies have reported metabolic effects of viable and inactivated L. rhamnosus GG in obesity models (de Oliveira Melo et al., 2023; Arellano-García et al., 2025). These findings support further investigation of viable and inactivated preparations of L. rhamnosus GG as potential bioactive ingredients for metabolic health in the context of obesity.