Background: Obesity and diet-induced metabolic disorders, particularly in the elderly, represent a growing public health concern. Chronic high-fat diet consumption impairs energy regulation, induces leptin resistance, and accelerates systemic inflammation and cellular aging. Objective: This study aimed to investigate the effects of tryptophan supplementation and High-Intensity Interval Training (HIIT) on the expression of inflammatory and metabolic genes in aged rats fed a high-fat diet. Methods: Thirty-six aged male Wistar rats (54 weeks old) were randomly assigned to five groups: normal diet control, high-fat diet, high-fat diet + HIIT, high-fat diet + tryptophan supplementation, and high-fat diet + HIIT + tryptophan supplementation. Tryptophan was administered at 100 mg/kg/day via gavage, while HIIT was performed for 8 weeks (three sessions per week). Gene expression of leptin, PPARγ, and NF-κB in visceral adipose tissue was measured using Real-Time PCR. Statistical analyses included independent t-tests, two-way ANOVA, and one-way ANOVA at p < 0.05. Results: HIIT significantly reduced leptin and NF-κB expression while increasing PPARγ. Tryptophan supplementation significantly decreased NF-κB but had non-significant effects on leptin and PPARγ. The combination of HIIT and supplementation demonstrated synergistic effects, with greater improvements in leptin sensitivity, PPARγ activation, and NF-κB suppression compared to either intervention alone. Conclusion: Both HIIT and tryptophan supplementation, individually and synergistically, modulate metabolic and inflammatory pathways in aged rats fed a high-fat diet. These findings suggest that integrating HIIT with tryptophan supplementation may serve as a multi-dimensional strategy for managing metabolic disorders and enhancing public health outcomes.