Intermittent fasting (IF), encompassing various regimens, garners attention for its multifaceted health benefits, which span metabolic improvements and the attenuation of age-related inflammation. Ramadan intermittent fasting (RIF), a prominent IF model, yields favorable outcomes in body composition, glucose regulation, lipid profiles, and liver function tests. Notably, RIF’s alteration of diurnal eating patterns underscores its role in chrono-nutrition interventions, which modulate nutritional metabolism via circadian rhythms. Targeting overnutrition through IF represents a pivotal strategy for mitigating these public health challenges. Fasting and caloric restriction represent effective interventions for disease prevention and aging delay. RIF affects the expression of different genes related to metabolism, inflammation, autophagy, oxidative stress, and other biological processes. This chapter discusses the impact of IF in general and RIF in particular on gene expression and signaling pathways involved in various metabolic, inflammatory, and other processes. A special focus on autophagy and the impact of gene variants on response to RIF is provided. A summary is provided for the clinical trials exploring the clinical and molecular underpinnings of fasting. It holds promise in elucidating its diverse biological effects and informing personalized health interventions. Finally, future perspectives and research opportunities are discussed.