LEP and Obesity: Several mechanisms may explain the oxidative stress increase in people with overweight/obesity, particularly (i) a decrease of antioxidant defenses, (ii) an increase in mitochondrial ROS production due to excessive energy expenditure, (iii) an increase in plasma lipids that are oxidation targets, (iv) an increase of the leptin level that may stimulate intracellular ROS production, and (v) ROS overproduction by adipose tissue due to cytokine release [41].