Background Physical activity (PA) breaks in sitting time might attenuate metabolic markers relevant to the prevention of type 2 diabetes. Objectives The primary aim of this paper was to systematically review and meta-analyse trials that compared the effects of breaking up prolonged sitting with bouts of PA throughout the day (INT) versus continuous sitting (SIT) on glucose, insulin and triacylglycerol (TAG) measures. A second aim was to compare the effects of INT versus continuous exercise (EX) on glucose, insulin and TAG measures. Methods The review followed the Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) recommendations. Eligibility criteria consisted of trials comparing INT vs. SIT or INT vs. one bout of EX before or after sitting, in participants aged 18 or above, who were classified as either metabolically healthy or impaired, but not with other major health conditions such as chronic obstructive pulmonary disease or peripheral arterial disease. Results A total of 42 studies were included in the overall review, whereas a total of 37 studies were included in the metaanalysis. There was a standardised mean difference (SMD) of − 0.54 (95% CI − 0.70, − 0.37, p = 0.00001) in favour of INT compared to SIT for glucose. With respect to insulin, there was an SMD of − 0.56 (95% CI − 0.74, − 0.38, p = 0.00001) in favour of INT. For TAG, there was an SMD of − 0.26 (95% CI − 0.44, − 0.09, p = 0.002) in favour of INT. Body mass index (BMI) was associated with glucose responses (β = − 0.05, 95% CI − 0.09, − 0.01, p = 0.01), and insulin (β = − 0.05, 95% CI − 0.10, − 0.006, p = 0.03), but not TAG (β = 0.02, 95% CI − 0.02, 0.06, p = 0.37). When energy expenditure was matched, there was an SMD of − 0.26 (95% CI − 0.50, − 0.02, p = 0.03) in favour of INT for glucose, but no statistically significant SMDs for insulin, i.e. 0.35 (95% CI − 0.37, 1.07, p = 0.35), or TAG i.e. 0.08 (95% CI − 0.22, 0.37, p = 0.62). It is worth noting that there was possible publication bias for TAG outcomes when PA breaks were compared with sitting. Conclusion The use of PA breaks during sitting moderately attenuated post-prandial glucose, insulin, and TAG, with greater glycaemic attenuation in people with higher BMI. There was a statistically significant small advantage for PA breaks over continuous exercise for attenuating glucose measures when exercise protocols were energy matched, but no statistically significant differences for insulin and TAG. PROSPERO Registration: CRD42017080982. PROSPERO Registration CRD42017080982. Key PointsBreaking up sitting with physical activity (PA) moderately attenuated post-prandial glucose and insulin, with a small effect size attenuation for TAG.There was greater glycaemic attenuation in people with higher body mass index (BMI).PA breaks were slightly more effective for glycaemic attenuation compared to one continuous bout of PA when experimental conditions were energy expenditure matched. Affiliations

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This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. Highlights  Orthodox fasting (OF) is a periodical vegetarian subset of the Mediterranean diet  We evaluated OF effects in general population fasters (GF) and Athonian monks (AM)  AM demonstrated lower BMI, Body Fat Mass and HOMA-IR values compared to GF  The results highlight the unique characteristics of Athonian OF as a healthpromoting diet  Limitation of specific vitamins and minerals during OF warrants further investigation