BOULDER, Colo. — Pythons are known for their enormous appetites. In a single meal they can devour animals at least as big as they are — deer, alligators, pigs, household pets.

Equally remarkable is what happens inside the python as it digests its prey. Within a day, its internal organs can double in size. Metabolic rate and production of insulin and lipids soar.

Then, like an accordion, the python’s organs return to normal size in just a few days. Metabolism slows. Then the snake can fast for months, even a year, without losing muscle mass or showing any ill effects, ready to ambush new prey.

How this process happens so rapidly is a biological mystery with important implications for human health, particularly when it comes to heart failure. Now scientists at the University of Colorado are reporting that they have partly solved it.