Figure 1

Intermittent fasting from dawn to sunset (dusk) for four weeks. Subjects fasted (no eating or drinking) for more than 14 h. daily for 29 days, from May 06, 2019, until June 03, 2019. The minimum required duration of daily fasting from dawn to sunset was 14 h., 8 min for the shortest day (May 6, 2019), and 14 h., 42 min for the longest day (June 03, 2019). Ramadan fasting is a unique form of intermittent fasting from dawn to sunset (dusk) without eating or drinking during the month of Ramadan based on the lunar calendar¹⁶ and has several major unique features: (1) Fasting is exclusively practiced during the human activity hours from dawn to sunset and is for both eating and drinking, which differentiates the dawn to sunset intermittent fasting from the other forms of intermittent fasting where eating light meals and/or drinking are allowed during the fasting window; (2) Although the main meals are at transition time zones of the day (pre-dawn breakfast and dinner at sunset), eating and drinking outside these transition time zones is allowed as long as it is within the non-fasting window; (3) There is no interventional calorie or energy restriction; (4) Daily fasting window is in synchrony with circadian rhythm and earth’s rotation on its axis because the daily fast starts at dawn (the first transition time zone of the day) after a pre-dawn breakfast and ends at sunset (dusk) (the second transition time zone of the day) with dinner; (5) Monthly fasting window is in synchrony with the moon’s rotation around the earth and lunar phases because the monthly fasting starts and ends when the new moon is sighted (with permission from Baylor College of Medicine).