Science Behind Chhath’s 36‑Hour Abstinence and Safety Tips

The sacred Chhath celebration includes a rigorous 36‑hour period in which participants consume neither food nor water. This ritual, rooted in devotion, places the human body under a unique metabolic stress.

Initially, the body relies on glycogen, a carbohydrate reserve stored mainly in the liver. Within 18‑24 hours of fasting, these stores are depleted, compelling the metabolism to shift toward fat oxidation. Fat molecules are broken down into fatty acids and glycerol; the liver converts some of these into ketone bodies, which become a secondary energy source for the brain and heart. Nevertheless, a minimal amount of glucose continues to be generated through gluconeogenesis to meet the needs of red blood cells and certain neural pathways.

Water deprivation impacts the circulatory system dramatically. Dehydration reduces plasma volume, prompting the hypothalamus to increase antidiuretic hormone secretion. The kidneys, in response, conserve water, causing a decline in urine production and a deepening of urine color.

A lower blood volume can precipitate hypotension, leading to dizziness, faintness, or visual disturbances when posture changes quickly. To counteract falling pressure, the heart may accelerate its rhythm, producing a noticeable rapid pulse.

Renal health is jeopardized when perfusion falls; insufficient blood flow hampers the kidneys' filtration capacity, potentially resulting in acute kidney injury. Electrolyte disturbances, especially drops in sodium and potassium, can cause muscle cramps, fatigue, and irregular heartbeats.

High‑risk individuals include people with diabetes who are on insulin or oral hypoglycemic agents, pregnant or breastfeeding women, minors, seniors, and patients with existing kidney, cardiac or liver disease. Those with chronic low blood pressure should also proceed with caution.

The consensus among health professionals is clear: before embarking on the 36‑hour dry fast, one should obtain medical clearance, stay vigilant for symptoms like pronounced dizziness, chest discomfort, or markedly reduced urine, and be prepared to end the fast if health deteriorates.