Periodical fasting, under a religious aspect, has been adopted by humans for centuries as a crucial pathway of induction of spiritual catharsis. Caloric restriction, with or without eviction of certain type of food, is a key component of most religious dietary patterns. Fasting varies significantly among different populations according to cultural habits and local climate condition. Religious fasting in terms of patterns (continuous vs. intermittent) and duration can vary from 1 to 200 days, thus their positive and negative impact on human health can be considerable.
Advantages of religious fasting on human health are claimed by many, but have been explored by a limited number of studies conducted in Buddhist, Christian or Muslim populations. These trials indicate that religious fasting has beneficial effects on body weight, glycaemia, cardiometabolic risk markers and oxidative stress parameters. Animals exposed to a mimicking fasting diet have demonstrated: weight loss, plasma levels of glucose, triglycerides and insulin growth factor-1, although their lean body mass remained stable. Diabetic mice on repeated intermittent fasting had less insulin resistance that mice fed ad libitum. The long term significance of such changes on global health remained to be explored.
This review summarizes the data available with regard to benefits of fasting followed for religious reasons on human health, body anthropometry and cardio-metabolic risk markers. It highlights current knowledge gap on available evidence and future research agenda. Future studies should explore every type of religious fasting, as well as their consequences in subpopulations such as children, pregnant women and elderly people, or patients with chronic metabolic diseases.