This randomized clinical trial investigated the impact of a 2-week sleep extension intervention on energy intake, energy expenditure, and body weight among 80 adults with overweight who habitually slept less than 6.5 hours per night. The study found that participants in the sleep extension group increased their sleep duration by approximately 1.2 hours per night, which led to a significant decrease in daily energy intake (average reduction of 270 kcal/d) and weight reduction compared to the control group. Because total energy expenditure did not change significantly, the reduced energy intake resulted in a negative energy balance, suggesting that improving sleep duration could be an effective strategy for obesity prevention and weight loss programs.