Background: Increased peak oxygen consumption (VO2peak) can reduce cardiovascular risks associated with obesity. Our aim was to analyze the effect of a weight loss program on cardiovascular fitness in overweight (W) and obese (O) subjects. Methods: One hundred and sixty-seven subjects (77 males and 90 females), aged 18-50 years, performed a modified Bruce protocol before (pre) and after (post) a weight loss program of 24 weeks. This program combined physical training (strength, S; endurance, E; combined strength + endurance, SE; or physical activity recommendation, PA) 3 times per week, with a 25%-30% caloric restriction diet. Results: VO2peak improved in overweight and obese males (pre and post values in L/min, respectively; W = 3.2 +/- 0.6 vs. 3.7 +/- 0.5, p < 0.001; O = 3.6 +/- 0.6 vs. 3.8 +/- 0.6, p = 0.013) as well as in overweight females (2.0 +/- 0.3 vs. 2.3 +/- 0.4, p < 0.001). VO2peak in the first ventilatory threshold (VT1) increased for all 4 interventions in males (p < 0.05), except for S in the obese group (1.6 +/- 0.2 vs. 1.7 +/- 0.3, p = 0.141). In females, it increased in E (0.9 +/- 0.2 vs. 1.4 +/- 0.3, p < 0.001), SE (0.9 +/- 0.2 vs. 1.2 +/- 0.4, p = 0.003), and PA (0.9 +/- 0.1 vs. 1.2 +/- 0.2, p = 0.006) in overweight groups. Time-to-exhaustion improved in all subjects except for females in PA group (15.7 +/- 0.3 min vs. 15.9 +/- 0.3 min, p = 0.495). Conclusion: Our results suggest that all methods, including the recommendation of physical activity, can improve cardiovascular fitness in overweight subjects and obese males. (c) 2017 Production and hosting by Elsevier B.V. on behalf of Shanghai University of Sport.