The earth rotates around its axis for 24 hours, this process creates physiological, biochemical, and behavioral rhythms in living things. These one-day periods are called the circadian rhythm. The circadian rhythm regulates human physiology and behavior by responding to environmental stimuli around the clock. The circadian system and sleep/wake phases are intertwined, and conditions such as sleep disorders, exposure to artificial light, jet lag, and shift work may cause disruptions in the circadian rhythm. Circadian rhythm; It is effective in gastrointestinal system physiology such as cell proliferation, electrolyte balance, digestion, absorption, motility. Disturbances in the circadian rhythm can cause imbalances in the intestinal flora, which can lead to disruptions in both the immune system and the absorption and digestion of macronutrients. In the human body, many endocrine factors are secreted in 24-hour periods and the amount of secretion reaches its peak at certain hours during the day. Disturbances in the circadian rhythm can cause many pathological conditions such as obesity and diabetes by causing disorders in the gastrointestinal system physiology, the secretion function of appetite hormones, and other endocrine factors secreted in 24 hours. Our aim in this review is to discuss the effects of circadian rhythm on gastrointestinal health and the relationship of hormones fluctuating with 24-hour circadian rhythm and obesity. The search was conducted in peer-reviewed journals PubMed, Web of Science, and Google Scholar. For this purpose, the keywords circadian rhythm and obesity were used together and research articles were included in this study.