Obesity is a global public health pandemic, closely linked to lifestyle changes. Modern lifestyles are often characterized by extended eating periods and reduced sleep duration, leading to circadian rhythm disruption. Circadian rhythm is pervasive among physiological activities and influences carbohydrate and lipid metabolism. The circadian clock generates self-sustaining 24-hour rhythms in cells, consisting of transcriptional–translational feedback loops. This review focuses on the circadian mechanisms underlying obesity. It provides an overview of the circadian clock theory, summarizes the relationship between environmental rhythmic factors, such as eating/fasting cycles, physical activity/rest cycles and sleep/wake cycles, and the pathogenesis of obesity. The brain-body communication framework is used involving the hypothalamus and adipose tissue to rationalize current research advances regarding circadian rhythms and obesity. Following this thread, the paper reviews current research progress on timerestricted eating and timed exercise, which leverages the interactions between intrinsic circadian systems and behavioral factors such as diet and exercise in the prevention and treatment of obesity. In the years of weight management, research and development of personalized interventions is an important direction for treating obesity. Incorporating circadian biology into both research and clinical practice will provide a strong theoretical basis for developing more precise strategies to combat obesity.