Cardiometabolic and obesity risk outcomes of dawn-to-dusk, dry intermittent fasting: Insights from an umbrella review

Abstract

Background & aims

This umbrella review comprehensively and systematically summarizes meta-analyses on the impact of dawn-to-dusk, dry intermittent fasting of Ramadan (RIF) on cardiometabolic and glucose homeostasis indicators.

Methods

Twenty meta-analyses were examined on the effects of RIF on body fat percentage (BFP), fat mass, fat-free mass, body mass index (BMI), body weight (BW), waist circumference (WC), systolic and diastolic blood pressure (SBP, DBP), high-density lipoprotein cholesterol (HDL-C), low-density lipoprotein cholesterol (LDL-C), total cholesterol (TC), triglycerides (TG), and very low-density lipoprotein cholesterol (VLDL-C), fasting blood glucose (FBG), glycated hemoglobin (HbA1c), insulin resistance (HOMA-IR), serum insulin, leptin, and adiponectin. Results of continuous outcomes were pooled from included meta-analyses. We employed random-effects meta-analysis using the restricted maximum likelihood method to estimate heterogeneity. P-values were derived from standard meta-analytic tests, including Egger's test for small-study effects and the excess significance test for potential publication bias. Additionally, we applied criteria from Ioannidis' evidence classification to assess the credibility of the findings.

Results

In healthy subjects, RIF was associated with significant reductions in BW (Hedges' G = −0.33; 95 % confidence interval (CI) = −0.37, −0.29; p-value = 2.63 × 10–52), WC (Hedges' G = −0.30; 95 % CI = −0.38, −0.23; p-value = 5.73 × 10–15), BFP (Hedges' G = −0.26; 95 % CI = −0.37, −0.14; p-value = 6.81 × 10-06), DBP (n = 3,456; Hedges' G = −0.26; 95 % CI = −0.38, −0.15; p-value = 9.18 × 10-06), TC (n = 9,314; Hedges' G = −0.16; 95 % CI = −0.25, −0.07; p-value = 6.27 × 10-04), and TG levels (n = 9,020; Hedges' G = −0.16; 95 % CI = −0.24, −0.08; p-value = 6.87 × 10-05). Moreover, in general population, TG (n = 16,688; Hedges' G = −0.15; 95 % CI = −0.22, −0.08; p-value <0.01) and FBG (n = 16,106; Hedges’ G = −0.23; 95 % CI = −0.33, −0.13; p-value <0.01) were significantly reduced.

Conclusions

Dawn-to-dusk, dry RIF shows promise as a complementary therapy and preventive measure for reducing cardiometabolic and obesity-related risks. However, controlled studies are necessary to validate its effectiveness and fully understand its health implications.