Fasting: Ancient Practice, Modern Question

Voluntary abstinence from food appears across many religious and contemplative traditions as prayer, discipline, mourning, purification, solidarity, or preparation. Medical fasting is a different category. It asks clinical questions about physiology, risk, and outcome, and it cannot borrow certainty from the spiritual meaning of a practice.

The word fasting also hides important differences. A religious fast, a nightly interval without food, time-restricted eating, alternate-day restriction, and prolonged water-only fasting are not interchangeable. Evidence about one form cannot automatically be applied to another.

Dr. Guillaume Guelpa (1850–1930), an Italian-born physician who worked in France, became known in the early twentieth century for combining periods without food with purgation and restricted diets. Guelpa and neurologist Alexandre Marie reported a fasting-based intervention for epilepsy in 1911. The report is historically important, but its methods, evidence, and safety standards do not support copying the treatment today.

German physician Dr. Otto Buchinger Sr. developed another influential European fasting tradition and published on fasting therapy, including a 1959 reflection on forty years of practice. His work belongs to the medical history of fasting; it should not be mistaken for the kind of large, controlled clinical evidence expected now.

Professor Yvon Le Maho, an emeritus CNRS research director and member of the French Academy of Sciences, studied how animals survive severe climates and long periods with limited food. His work with penguins helped describe extraordinary metabolic adaptation in the natural world.

That research helps scientists ask better questions about energy use and adaptation. It does not prove that prolonged fasting is therapeutic for people. Animal adaptation and human clinical care are different kinds of evidence.

Researchers including Rafael de Cabo at the National Institute on Aging and neuroscientist Mark Mattson at the NIH and Johns Hopkins have examined the biological mechanisms and possible health effects of intermittent fasting. Their work helped establish fasting as a serious scientific subject, particularly around metabolic switching, aging, and neurological resilience.

Interest is not the same as proof. France’s INSERM concluded in its 2014 assessment that rigorous clinical studies of therapeutic fasting were too few and methodologically limited to establish clinical benefit. More recent trials have expanded the literature, but a 2026 Cochrane review still found that intermittent fasting may make little to no difference in weight loss compared with conventional dietary advice, with uncertainty remaining around unwanted effects and long-term outcomes.

Fasting sits at a rare meeting point: inherited ritual, personal discipline, evolutionary physiology, and clinical research. It raises questions about rhythm, appetite, attention, energy, and the difference between discomfort chosen with care and deprivation that causes harm.

RA SPHERA holds the subject as a field of inquiry rather than a prescription. The connection to bodywork is philosophical—not a claim that massage and fasting produce the same effects. Both invite attention to timing, recovery, and the body’s response to changing conditions.

This page deliberately gives no duration, calorie target, schedule, or step-by-step method. Children and adolescents, people who are pregnant or breastfeeding, people with a history of an eating disorder, and people with type 1 diabetes should not begin intermittent fasting from general internet guidance. Diabetes, kidney or liver disease, frailty, medications, athletic training, and other health conditions can also change the risks and require individualized professional advice.

Fasting can cause fatigue, dizziness, headache, nausea, mood changes, constipation, and low blood sugar in susceptible people. A spiritual practice and a medical intervention may share a name, but neither should be used to silence the body’s warning signs.