Background :Overweight and obesity have become a problem for younger generations, so weight management must be introduced. Moderate-intensity interval training (MIIT) has been recommended for aging and obese populations because it is friendly and accessible. However, little information is known about the physiological response during moderate-interval intensity exercise, especially for overweight and obese persons. Objectives :To evaluate cardiorespiratory alteration upon a single bout of MIIT exercise among sedentary, overweight young Thai adults. Methods :Fifteen overweight young adults (8 males and 7 females, body mass index between 25.0 - 29.9 kg/m2, aged between 18 - 25 years) underwent cycling ergometry for 45 minutes (warm-up 5 minutes; 3 × 5 minutes at 20 - 40% of heart rate reserve and 5 minutes at 50 - 60%; cool down 10 minutes). A gas analyzer and limb lead electrocardiogram were used to record Oxygen Consumption (V̇O2), heart rate (HR), and dioxide production (V̇CO2) throughout the experiment. Results :During the 45-minute MIIT exercise protocol, the participants consumed 25.1 ± 8.1 L, equal to approximately 530 ± 171 kJ. As expected, heart rate, O2 uptake, and CO2 production increased during moderated-intensity exercise and declined during low-intensity exercise. A low to moderate duration ratio of 1: 1 was sufficient to return both O2 Consumption and CO2 production to their stage level, but not for heart rate. Although there was a very linear relationship between V̇O2 and heart rate for the overall period (0.761 ± 0.090), the correlation was weaker when selectively computed during low (0.549 ± 0.161) or moderate exercises (0.658 ± 0.105). Interestingly, RER larger than one during moderate-intensity exercise indicated the possibility of high acid accumulation. Conclusions :The MIIT protocol in the present study provided a responsive effect on overweight persons toward anaerobic metabolism but was a little aggressive.