Y: Don, tell me, when’s the last time you can remember seeing an obese animal in the wild?
D: Hmmm. Yaël, I’m not sure I can remember one. Do animals in the wild ever really become obese?
Y: The provisional answer is “No.” But do wild animals ever overeat and what happens if they do?
D: Many species of animals certainly do overeat, for various reasons. A male lion can eat as much as ninety pounds in one feeding. For an average-sized lion, that’s about twenty percent of his body weight!
Y: The lion gorges himself because he may not get another hunting and feeding frenzy for another several days or weeks. It’s clear that their ability to overeat is a strategic evolutionary trait.
D: We observe a similar kind of gorging habit in birds before they embark on long, transoceanic flights or in bears before they hunker down for a months-long hibernation.
Y: But an animal will not just constantly overeat. The accumulated dead weight would slow them down, making them a less competitive predator and inducing them to slim down again.
D: Herbivores aren’t driven by such direct predator-prey competition. Their food supply typically includes leaves and grasses that are nutrient-poor. Elephants consume hefty quantities of greenery but don’t get large amounts of energy or carbs from this diet. In fact, elephants are relatively trim for their size.
Y: A mouse is one animal that will overeat to the point of being overweight if it stumbles upon an unexpected surplus of food. But these rodents will almost immediately begin to produce offspring. Before long, the search for food and providing milk for the young ensures the overweight few becomes a family of trim scavengers once again.