Animal model studies involving macaúba oil demonstrate beneficial effects on fat, oxidative stress, and adipogenesis. This study aims to evaluate lipid oxidation and mental stress levels in trained individuals following macaúba oil supplementation combined with outdoor exercise (green exercise) performed in a fasted state. The study will be randomized, double-blind, and placebo-controlled. Participants will receive either 400 mg of macaúba oil or placebo pills over an 8-week period while engaging in 5 km running sessions four times a week. Assessments of anthropometric parameters, body composition (DEXA), biochemical parameters, and heart rate will be conducted before and after the intervention, alongside the administration of a questionnaire regarding emotional well-being and perceived stress. At the end of the intervention, results will be analyzed using Kubios HRV 2.0 and GraphPad Prism (version 5.0) software; the Kolmogorov-Smirnov and Shapiro-Wilk tests will be applied to verify data normality, the Student's t-test for parametric data, and the Kruskal-Wallis and Wilcoxon-Mann-Whitney tests for non-parametric data.