PT - JOURNAL ARTICLE AU - Mandal, Sumona AU - Simmons, Niall AU - Awan, Sidra AU - Chamari, Karim AU - Ahmed, Irfan TI - Intermittent fasting: eating by the clock for health and exercise performance AID - 10.1136/bmjsem-2021-001206 DP - 2022 Jan 01 TA - BMJ Open Sport & Exercise Medicine PG - e001206 VI - 8 IP - 1 4099 - http://bmjopensem.bmj.com/content/8/1/e001206.short 4100 - http://bmjopensem.bmj.com/content/8/1/e001206.full SO - BMJ OPEN SP EX MED2022 Jan 01; 8 AB - Intermittent fasting (IF) is an increasingly popular dietary practice, and its implementation is found throughout human civilisation in various cultural, spiritual and religious traditions. Emerging evidence has shown that the health benefits of IF stretch beyond calorie restriction and weight loss. These benefits include metabolic shifts in energy production, the optimisation of peripheral circadian clocks, and overall improvement in physiological markers of metabolic health. IF has been proposed to reduce systemic inflammation and have a role in the prevention and treatment of chronic disease. For the athlete, IF protocols offer a potential new frontier for maintaining performance in the fasted state. They may allow athletes to optimise training adaptions, while respecting individual cultural, religious, and/or spiritual preferences to fast and exercise. Below, we discuss the physiological impact of fasted exercise while highlighting areas for future work to improve our understanding and implementation of the practice for the benefit of both the active general community and sporting populations.