Fasting
Fasting spans physiology, medicine, religion, and political protest.
Fasting is the act of refraining from eating, and sometimes drinking. It has physiological, medical, religious, and political dimensions, ranging from metabolic states after overnight abstinence to prolonged fasts for health investigation or protest.
- types
- Diagnostic, intermittent, prolonged, religious, political
- common_purposes
- Medical tests, weight loss, religious ritual, political protest
- notable_practitioners
- Gandhi, Bobby Sands, César Chávez
- adverse_effects
- Refeeding syndrome, gallstones, electrolyte imbalances
Lore & Background
Fasting is practiced in various religions, with details differing. In Judaism, Yom Kippur and Tisha B'Av are 25-hour fasts; other fasts last from dawn to nightfall. In Christianity, Lent is a common fasting period, with Catholic and Lutheran traditions specifying days of fast and abstinence, such as Ash Wednesday and Good Friday. The Eucharistic Fast in the Latin Church requires taking nothing but water or medicine for one hour before receiving the Eucharist.
Reader's Guide
Fasting has significant medical applications, including before surgery to prevent pulmonary aspiration, and before certain tests like cholesterol or blood glucose measurements. Intermittent fasting shows little evidence for sustained weight loss in obese adults for periods under 24 hours, though alternate-day fasting for two to six months may reduce body weight and cardiometabolic risk factors. Prolonged fasting beyond 24 hours can lead to ketosis and weight loss, but also risks electrolyte imbalances and refeeding syndrome. There is no sound clinical evidence that fasting promotes longevity in humans. Politically, hunger strikes have been used as non-violent resistance, notably by Gandhi, Bobby Sands, and César Chávez.
Did You Know?
- Refeeding syndrome can occur after 4–5 days without food.
- Bobby Sands died after 66 days of not eating during a hunger strike.
- Alternate-day fasting for 2–6 months reduced body weight and cardiometabolic risk factors in overweight or obese adults.
Frequently Asked Questions
What is fasting and what forms does it take?
Fasting refers to deliberately withholding food and, in some traditions, also liquids for a set period. It ranges from short overnight abstinence to extended multi-day or multi-week practices, and can be undertaken for diagnostic, spiritual, or activist reasons.
Which well-known figures used fasting as a form of protest?
Mahatma Gandhi, Bobby Sands, and César Chávez are among the most recognized individuals who employed hunger strikes to advance political or civil-rights causes. Their fasts became powerful symbols of nonviolent resistance within their respective movements.
What are the main religious and practical reasons people fast?
Many faith traditions incorporate fasting as a ritual of devotion, self-discipline, or spiritual purification. Outside religion, people also fast to aid medical diagnostics, manage body weight, or draw public attention to a political cause.
What medical dangers can prolonged fasting cause?
Extended abstinence from food carries risks such as dangerous shifts in electrolyte levels, the formation of gallstones, and a potentially fatal condition called refeeding syndrome when nutrition is reintroduced too quickly. These complications are why medical supervision is strongly advised for long fasts.
How does fasting differ from simply skipping a meal?
A single skipped meal triggers only a brief metabolic shift, whereas structured fasting—whether intermittent, diagnostic, or prolonged—involves a deliberate, often repeated pattern of abstinence. The intentionality and duration distinguish a true fast from a casual gap between meals.
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