Study subjects
A total of 140 subjects (70 fasting and 70 non-fasting) Orthodox Christian followers residing in the Hawassa city government and meeting the inclusion criteria were contacted. The inclusion criteria were as follows: apparently healthy subjects belonging to Orthodox Christian communities aged between 30 and 45 years, permanently residing in the area and who neither smoked nor drank alcohol (1 or 2 servings/week). Subjects lived permanently in the study area and had no plans to leave prior to completion of the study. Exclusion criteria were as follows: subjects with any health abnormalities, pregnant or lactating women, and those intending to leave the study site prior to study completion.
ethical consideration
The protocol and questionnaires were reviewed and approved by the Natural and Computational Science Ethics Review Board of Addis Ababa University, Ethiopia (IRB/035/2018). All methods were performed in accordance with the ethical principles of the Declaration of Helsinki for medical research involving human subjects. The nature of the study was fully explained to the study participant and written informed consent was obtained from each participant prior to the study. The data collected was kept confidential.
Study design, sampling and sample size
This study was conducted during the Assumption and Christmas fasting periods from August 2018 to January 2019 in Hawassa, Ethiopia. Sample size was calculated using GPower to allow comparison between two groups, assuming =0.05, power=0.85, a mean effect size (1-2)/=0.5, repeated measures correlation ()=0.6 and considering repeated measures of four times points, as follows:
$$N = \frac{{2\left( {z_{\alpha } + z_{\beta } } \right)^{2} \left( {1 + \left( {n – 1} \right)\ rho } \right)}}{{n\left[ {\left( {\mu_{1} – \mu_{2} } \right)/\sigma } \right]}}$$
(1)
Where 2 is the assumed common variance in the two groups, 12 is the difference in the means of the two groups; n is the number of time points and is the assumed correlation of the repeated measures. This resulted in a minimum sample size of 38 subjects per group, which was increased to 55 subjects per arm after representing a maximum 30% loss to follow-up. A total of 110 subjects (55 per arm) completed the study (Fig.1).
Flowchart of study design and allocation of participants during the study.
Fasting regimen
The fasting group strictly followed the practice of Ethiopian Orthodox fasting by skipping at least one meal (breakfast), then strictly adhering to a vegan diet devoid of any form of animal-based foods. The fasting group fasted: (i) Assumption fast (15 days) and (ii) Nativity/Christmas fast (44 days) and (iii) Wednesday and Friday fasts performed throughout the year except the month following Easter. Conversely, the non-fasting group continued with their normal eating habits.
Socio-demographic factors and lifestyle
A standardized questionnaire was used to collect data on lifestyle and demographic factors. Physical activity levels were defined as physically active if participants exercised three or more times a week for >30 minutes, moderately active if they exercised 2 times a week, less physically active if they exercised 1 time a week, and sedentary if not physically active.
Outcome measures
Anthropometric and body composition measurements were performed at four time points: one week before the start and one day before the end of the Assumption fast. For the Nativity (Christmas) fast, measurements were taken one week before the start and at the end of the fast. All repeated measurements were obtained at the same time of day (1h).
Anthropometry
Height was measured in bare feet to the nearest 0.1 cm with a stadiometer. Body weight was measured twice wearing light clothing to the nearest 100 g using a digital scale. Both height and weight were measured following standard procedures. An adult digital electronic scale (ASTO) was used for the measurement, which measures both weight and height. Body mass index (BMI) was calculated as weight in kilograms divided by the square of height measured in meters.
Body composition
Subjects’ body composition was measured using a bioelectrical impedance analyzer (model Tanita BC-418, Tokyo, Japan) with a range of 0200 kg and an accuracy of ~100 g.
Data quality control
Data collection was conducted by expert interviewers. Anthropometric and body composition measurements were conducted by an experienced clinical technician following standard procedures.
statistic analysis
All data were checked for consistency and completeness, coded, and entered into Statistical Package for Social Sciences (SPSS) version 23.0 software for analysis. The normality of the continuous data distribution was verified using the ShapiroWilk test. Descriptive statistics such as frequency and percentages were used to describe the dependent variable in relation to several categorical data, while mean (percentage increase) and SD or standard error was used for continuous data. In addition, the estimate of variances in study group means was assessed using the student’s t-test at the 95% confidence interval (CI) level. A two-way ANOVA was performed to evaluate the time-fast interactions. P– values <0.05 were considered statistically significant.
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