Roasted yerba mate and prolonged swimming: effects on body composition, muscle function, and glucose metabolism in obese mice

Introduction: Obesity is associated with impaired glucose homeostasis. Exercise is a primary non-pharmacological intervention, whereas the effects of roasted yerba mate combined with prolonged exercise remain poorly understood. Objective: To investigate the isolated and combined effects of roasted yerba mate (Ilex paraguariensis) and prolonged swimming on body composition, muscle function, and glucose metabolism in obese mice. Methodology: Forty male Swiss Webster mice received a cafeteria diet for 30 days and were randomly assigned to five groups: control, obese sedentary, obese sedentary with yerba mate, obese swimming, and obese swimming with yerba mate. Yerba mate infusion was administered for 30 days, and swimming was performed for 60 minutes daily, five days per week. Assessments included dual-energy X-ray absorptiometry, the inverted grid test, and fasting glucose and insulin measurements. Results: The swimming groups showed the lowest body weights, while body fat percentage did not differ among obese groups. Only the combined intervention differed from the obese sedentary group in fat-free mass, fasting glucose, and insulin, with values comparable to controls. All interventions reduced insulin resistance. No intervention improved inverted grid test performance. Discussion: Reduced insulin resistance was consistent with previous rodent studies of yerba mate, despite the lower dose used. The absence of functional improvements may be related to the aerobic nature of swimming. Conclusions: Roasted yerba mate combined with prolonged swimming was associated with a more favorable glycemic profile and lower insulin resistance in obese mice. Further studies should investigate muscle quality and the underlying mechanisms.