Cardiovascular and autonomic nervous system remodeling during Ramadan fasting: A narrative review

Ramadan fasting is a unique form of intermittent fasting characterized by abstinence from food and fluids from dawn to sunset for approximately one lunar month. This practice induces alterations in circadian rhythm, metabolism, hemodynamics, and neurohumoral regulation, all of which may influence cardiovascular (CV) physiology and autonomic nervous system (ANS) function. To synthesize evidence published between 2015 and 2025 on CV and ANS remodeling during Ramadan fasting, a narrative review of PubMed-indexed human studies (2015–2025) was conducted, focusing on CV outcomes, blood pressure, lipid metabolism, heart rate variability (HRV), and autonomic regulation during Ramadan fasting. Most studies report no increase in acute CV events during Ramadan in healthy individuals or stable cardiac patients. Modest improvements in blood pressure, lipid profile, body weight, and insulin sensitivity are frequently observed. Autonomic adaptations assessed through HRV demonstrate heterogeneous findings, with transient sympathetic predominance in some cohorts and preserved or enhanced parasympathetic activity in others. Ramadan fasting induces short-term CV and autonomic remodeling that is generally adaptive and clinically safe in stable individuals. However, methodological heterogeneity, limited long-term data, and underrepresentation of high-risk populations remain important gaps in current evidence.