TABLE 1.

Table of inclusion and exclusion criteria following the PICOS approach¹.

PICOS	Inclusion and exclusion criteria	Data extraction
Participants	Adult population’s ≥18 and ≤65 years or animal samples were included.	Age, sex, gender, sample size, location, inclusion and exclusion criteria
Intervention	Types of fasting regimens were classified into two main subgroups (time restricted fasting including Ramadan fasting and 8/16 h fasting program and calorie restricted fasting including alternate day fasting, water only fasting and the Buchinger program).	Types of fasting regimens, fasting duration
Comparators	Only studies with control group were included, participants or animal models with normal diet.	Type of comparator, compliance
Outcomes	Changes in the gut microbiota.	Outcomes measured, evaluation methods and side effects.
Study design	Studies were excluded if the main text was not available or was not in the English language. Reviews, protocols, conference papers, and case reports were also excluded. Therefore, only original researches with original data on animal models or human patients exploring any kind of fasting regimes on gut microbiota were included in the present study.	Design of the study, loss of the study

¹PICOS, participants, intervention, comparator, outcome, study type.