Abstract
Background: Religiously motivated Bahá'í fasting (BF) is a form of intermittent dry fasting celebrated by abstaining from food and drinks during daylight hours every year in March for 19 consecutive days.Aim: To test the safety and effects of BF on hydration, metabolism, and the circadian clock.Methods: Thirty-four healthy Bahá'í volunteers (15 women) participated in this prospective, exploratory cohort study. Laboratory examinations were carried out in four study visits: before fasting (V0), in the third week of fasting (V1) as well as 3 weeks (V3) and 3 months (V4) after fasting. Data collection included blood and urine samples, anthropometric measurements and bioelectrical impedance analysis. At V0 and V1, 24- and 12-hour urine and serum osmolality were measured. At V0–V2, alterations in the circadian clock phase were monitored in 16 participants. Our study was augmented by an additional survey with 144 healthy Bahá'í volunteers filling out questionnaires and with subgroups attending metabolic measurements (n = 11) and qualitative interviews (n = 13), the results of which will be published separately.Results: Exploratory data analysis revealed that serum osmolality (n = 34, p < 0.001) and 24-hour urine osmolality (n = 34, p = 0.003) decreased during daytime fasting but remained largely within the physiological range and returned to pre-fasting levels during night hours. BMI (body mass index), total body fat mass, and resting metabolic rate decreased during fasting (n = 34, p < 0.001), while body cell mass and body water appeared unchanged. The circadian phase estimated by transcript biomarkers of blood monocytes advanced by 1.1 h (n = 16, p < 0.005) during fasting and returned to pre-fasting values 3 weeks after fasting. Most observed changes were not detectable anymore 3 months after fasting.Conclusions: Results indicate that BF (Bahá'í fasting) is safe, has no negative effects on hydration, can improve fat metabolism and can cause transient phase shifts of circadian rhythms.Trial Registration:https://www.clinicaltrials.gov/, identifier: NCT03443739.
Highlights
Fasting with its preventive and therapeutic effects has, in general, been explored more and more over the past decade [1,2,3,4,5,6,7,8,9,10]
Since research has suggested that Ramadan fasting causes alterations of normal circadian rhythms [23], we explored the effects of Bahá’í fasting (BF) on the circadian phase
Thirty-four volunteers (15 w, 19 m, age: 41.09 ± 14.54 years) practicing BF and living in or near Berlin participated in the visits and tests of physiological parameters
Summary
Fasting with its preventive and therapeutic effects has, in general, been explored more and more over the past decade [1,2,3,4,5,6,7,8,9,10]. Dry fasting (DF) has not received as much attention in the scientific community. Most studies in this regard have focused on the Ramadan fast [11, 12], not exploring DF as such, while serious consequences of a dysregulated body fluid balance are clear for every clinician [13], making studies on DF difficult to conduct. Ramadan fasting is a complex model for DF, as the daily duration of fasting varies greatly over the years (from 11 to 22 hours a day, depending on the season and geographic location) [14]. Motivated Bahá’í fasting (BF) is a form of intermittent dry fasting celebrated by abstaining from food and drinks during daylight hours every year in March for 19 consecutive days
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