Effect of the one-day fasting on cortisol and DHEA daily rhythm regarding sex, chronotype, and age among obese adults

Abstract

Introduction: Physiological and biochemical processes in the human body occur in a specific order and show rhythmic variability. Time dependence characterizes the secretion of cortisol and dehydroepiandrosterone (DHEA). One-day fasting implies alternating fasting days and eating days. The study aimed to determine how 24-h fasting affects the daily rhythm of cortisol and DHEA levels in obese people while taking into account gender and chronotype.

Methods: Forty-nine obese patients (BMI 32.2-67.1 kg/m²; 25 women and 24 men) underwent a 3-week hospital-controlled calorie restriction diet to reduce body weight. During hospitalization, patients fasted for 1 day, during which only water could be consumed. Samples of whole mixed unstimulated saliva were collected at 2-3-h intervals over a 64-h period and analyzed for cortisol and DHEA by immunoassays. The individual chronotypes were assessed by the morning and evening questionnaire, according to Horne and Östberg. Three components of daily rhythm were evaluated: amplitude, acrophase, and the so-called MESOR.

Results: Cortisol rhythm showed differences in amplitude (p = 0.0127) and acrophase (p = 0.0005). The amplitude on the fasting day was 11% higher (p = 0.224) than the day after. The acrophase advanced on the day of fasting, 48 min earlier than the day before (p = 0.0064), and by 39 min to the day after fasting (p = 0.0005). In the rhythm of DHEA, differences were found in the MESOR (p = 0.0381). The MESOR on the fasting day increased.

Discussion: Our results obtained during 64 consecutive hours of saliva sampling suggest that one-day fasting may affect three components of cortisol and DHEA daily rhythm. Additionally, no differences were found in the daily rhythm between the morning and evening chronotypes and between females and males. Although aging did not influence daily cortisol rhythm, DHEA amplitude, MESOR, and acrophase changed with age. To the best of our knowledge, this is the first presentation of changes in DHEA rhythm during one-day fasting.

Keywords: DHEA; cortisol; fasting; obesity; rhythm.

Figure 1

Study protocol. Each subject underwent a protocol schedule with 3-week controlled calorie restriction diet in the hospital. Unstimulated saliva were collected over a 64-h period at 2–3-h intervals starting at 08:00 during the course of three consecutive days for the daily rhythm of cortisol and DHEA. In addition, an initial and final sample of blood on day 0 and day 21 was obtained for biochemical parameters.

Figure 2

Time course of cortisol concentration (ng/ml) for 64 h in: (A) day 1 (day before fasting), (B) day 2 (fasting day), (C) day 3 (day after fasting), n = 49. Each value is the median (min-max).

Figure 3

(A) Area under the curve (AUC) of the time course of cortisol levels day 1 (day before fasting) and day 2 (fasting day). The AUC was calculated for each patient separately (n = 49), and the mean value of day 1 and day 2 were compared. (B) Area under the curve (AUC) of the time course of DHEA levels day 1 (day before fasting) and day 2 (fasting day). The AUC was calculated for each patient separately (n = 15), and the mean value of day 1 and day 2 were compared. Values are expressed as median (min-max). A value of p < 0.05 was considered significant. The data were analyzed with the Wilcoxon test.

Figure 4

Time course of DHEA concentration (pg/ml) for 64 h in: (A) day 1 (day before fasting), (B) day 2 (fasting day), (C) day 3 (day after fasting), n = 15. Each value is the median (min-max).