Table 1 Inclusion and exclusion criteria

Inclusion criteria

 General populations of free-living adults (of ≥ 18 years of age)

 Clinical trial comparing interventions of low (three or less) vs high (four or more) meal frequency (Randomized controlled trial, crossover or parallel controlled trial)

 Reported an outcome related to body composition (e.g. bodyweight, BMI) and/or a surrogate marker of cardio-metabolic disease (e.g. fasting blood glucose, Hemoglobin A1c (HbA1c), lipids)

Exclusion criteria

 Studies of participants with altered body composition due to external factors, including, but not limited to pregnancy, malignancy, eating disorders, smokers, elite athletes, or a history of bariatric surgery

 Interventions of less than two weeks duration

 Trials focussed on fasting for longer than 24 h (explicitly less than one meal per day)

 Cross-over studies with a washout period of less than one week

 Uncontrolled medication use between intervention groups (e.g. one trial arm using medications known to effect weight change)

 Undefined eating frequency observed by participants

 Measurements of body composition were not standardised

 Inclusion of dietary supplements, pharmacological interventions or commercial diet replacement foods as part of the main intervention

 Conference abstracts or proceedings papers