How long can a mouse go without eating? - briefly
A mouse generally endures 2–3 days without food, and under optimal conditions can survive up to about a week. Lack of water is far more lethal, causing death within 24–48 hours.
How long can a mouse go without eating? - in detail
Mice can endure periods without solid food considerably longer than many other small mammals because of their high metabolic efficiency and the ability to mobilize stored energy. Under laboratory conditions, healthy adult mice typically survive 2–3 weeks without any intake of food, provided water remains available. Survival time varies with several factors:
- Body condition: Animals with greater fat reserves extend fasting length; underweight individuals may succumb within 7–10 days.
- Age: Young adults show the longest tolerance; juveniles and geriatric mice experience earlier decline.
- Strain: Certain inbred strains (e.g., C57BL/6) display a slightly longer fasting capacity than others (e.g., BALB/c), reflecting genetic differences in metabolism.
- Ambient temperature: Cooler environments reduce energy expenditure, permitting a modest increase in fasting duration; at standard housing temperature (≈22 °C) the 2–3‑week window holds.
- Water access: Deprivation of both food and water dramatically shortens survival to 2–4 days; hydration alone is essential for prolonged fasting.
Physiologically, the initial 24 hours trigger glycogenolysis, using liver glycogen to maintain blood glucose. After glycogen stores deplete, gluconeogenesis and lipolysis dominate, providing glucose from amino acids and ketone bodies from fatty acids. Muscle protein catabolism begins around day 3–4, supplying substrates for gluconeogenesis while preserving essential organ function. By the second week, ketone production peaks, allowing the brain to rely on alternative fuels and reducing the rate of protein loss. Prolonged fasting beyond three weeks leads to severe cachexia, organ failure, and eventual death.
Experimental studies employing controlled food deprivation report a median survival of 16 days for adult C57BL/6 mice with ad libitum water. Extending the period to 21 days results in a marked increase in mortality, with only a minority of individuals surviving to the fourth week. Researchers often use this window to investigate metabolic adaptation, autophagy, and disease models, but ethical guidelines require careful monitoring of body weight (loss >20 % triggers humane endpoints) and clinical signs.
In summary, a mouse can persist without nourishment for roughly two to three weeks, contingent on its physiological state, genetic background, ambient conditions, and continuous water supply. Beyond this interval, the depletion of vital energy stores precipitates irreversible decline.