Ramadan intermittent fasting may affect whole-body metabolism by affecting appetite-related hormones. This systematic review and meta-analysis aimed to clarify the possible effects of Ramadan intermittent fasting on the main hormones regulating appetite and satiety, including leptin and adiponectin.
All English language papers in the PubMed, Scopus, and Embase databases were searched using the keywords “Ramadan fasting”, “adiponectin”, and “leptin”, up to 2020. Data extraction was conducted based on the main data of the studies; the primary outcomes of the analysis were mean changes of adiponectin and leptin levels during the holy month of Ramadan in fasted subjects.
Data of 16 eligible studies, conducted between 2003 and 2020, were included in the systematic review. Of these, 10 studies with complete data on leptin and adiponectin were included in the meta-analysis. A significant decrease in leptin levels was observed after Ramadan fasting (WMD = −2.28 ng/ml, 95% CI = −3.72, −0.84). Ramadan fasting had no significant effect on adiponectin levels (WMD = 2.19 ng/ml, 95% CI = −0.29, 4.67). Sub-group analysis demonstrated a greater decrease in leptin levels among normal-weight subjects compared to those of overweight/obese subjects (WMD = −4.67 ng/ml, 95% CI = −6.03, −3.31 vs. WMD = −3.43 ng/ml, 95% CI = −5.69, −1.17).
Ramadan fasting may decrease leptin levels, especially in normal-weight subjects. There was high heterogeneity, which may be explained by the differences between the wide ranges of study conditions.
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This study was supported by the Research Institute for Endocrine Sciences, Shahid Beheshti University of Medical Sciences.
This work was not supported by any funding agency.
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The study protocol was approved by the ethics research council of the Research Institute for Endocrine Science, Shahid Beheshti University of Medical Science in Tehran.
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Gaeini, Z., Mirmiran, P. & Bahadoran, Z. Effects of Ramadan intermittent fasting on leptin and adiponectin: a systematic review and meta-analysis. Hormones (2021). https://doi.org/10.1007/s42000-021-00285-3
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