Effects of Christian Orthodox Fasting Versus Time-Restricted Eating on Plasma Irisin Concentrations Among Overweight Metabolically Healthy Individuals

Abstract

Irisin has been recently identified as an adipomyokine produced during physical activity and involved in the browning of adipose tissue. Despite the emerging evidence suggesting an inverse relationship between irisin plasma concentrations and adverse metabolic outcomes, the exact impact of diet on irisin levels remains obscure. Thus, we aimed to assess the effects of two dietary patterns, Christian Orthodox fasting (OF) and 16:8 time-restricted eating (TRE), on circulating irisin levels among overweight, metabolically healthy, adults. Plasma irisin, glucose and lipid parameters, calcium homeostasis, and anthropometry were evaluated in 29 Orthodox fasters and 14 age and body mass index (BMI)-matched TRE controls (mean age and BMI, 48.8 years and 28.7 kg/m2, respectively) at three, distinct time points—before the implementation of the energy-restricted diets (baseline), at the end of the dietary intervention (7 weeks) and 5 weeks after participants returned to their typical dietary habits (12 weeks from baseline). Repeated measures analysis was applied to assess differences between the two groups and the effect of several indices on irisin levels at all three time points. At 12 weeks, the OF group manifested higher irisin concentrations compared with both its baseline values (64.3 ± 54.4 vs. 43.6 ± 42.2 ng/mL, p = 0.01) and those of the TRE group at the same time point (64.3 ± 54.4 vs. 44.2 ± 26.6 ng/mL, p = 0.04). Glycemic, lipid, and anthropometric parameters were not found to correlate with irisin levels. In contrast, parathyroid hormone (PTH) concentrations at 12 weeks correlated with irisin concentrations (p = 0.04), indicating that lower values of irisin are expected for higher PTH measurements. The findings of this pilot study suggest favorable long-term effects of OF on irisin levels. The interplay between irisin, PTH, and diet warrants further investigation.

Religious fasting and its impacts on individual, public, and planetary health: Fasting as a “religious health asset” for a healthier, more equitable, and sustainable society

“…Other recent studies showed the beneficial effect of COC fasting on metabolic health indices ( 148 , 149 , 158 ). For example, it has been shown that COC fasting has superior lipid-lowering effects compared to the TRE pattern in overweight adults ( 148 ).…”

“…For example, it has been shown that COC fasting has superior lipid-lowering effects compared to the TRE pattern in overweight adults ( 148 ). In addition, the favorable long-term effects of COC on irisin levels (involved in the adipose tissue browning) in overweight, metabolically healthy, adults have been shown ( 158 ).…”

Ramadan Fasting Improves Body Composition without Exacerbating Depression in Males with Diagnosed Major Depressive Disorders

“…Future randomized studies are needed to eliminate the bias of the self-selection of fasting as an intervention. Randomization is truly unfeasible in studies investigating religious types of fasting [ 47 ]; nonetheless, more rigorous research is needed.…”

Circulating irisin in nonalcoholic fatty liver disease: an updated meta-analysis

“…It remains unclear whether it is NAFLD itself or its comorbidities such as obesity or diabetes that affects circulating irisin, while most of the included studies failed to control for such factors when making comparisons. Moreover, data on lifestyle factors such as physical activity and nutrient intake were not well reported, which may also influence the comparison of irisin levels in NAFLD versus controls [8,36,37]. Third, although irisin has been proven to exist [38], the accuracy of the ELISA kits used for its detection remains unclear and needs to be validated against mass spectrometry [39,40].…”