A Moment of Science

Gorillas Are Being Put On Diets

Many gorillas in zoos are overweight and dying of heart disease in their twenties and thirties when they could live to be twice that age.

gorilla popping up behind a log

Photo: Kris Elshout (Flickr)

Are you ready for some veggies?

There are over three hundred fifty lowland gorillas living in fifty two zoos across the U.S. They are a favorite of the public, probably because they remind us so much of ourselves. Unfortunately, zoo gorillas are not only like us, they reflect our current society more than we’d imagined. Many are overweight and dying of heart disease in their twenties and thirties when they could live to be twice that age.

Hefty Gorillas

Gorillas are native to Africa, and in the wild travel long distances while foraging. They typically eat large amounts of green plant material which is high in fiber and low in calories. In contrast, gorillas in zoos consume a fast food diet that is mostly commercially prepared biscuits and domesticated fruit, a diet that is lower in fiber and often higher in calories.

Concerned that zoo diets are one culprit underlying heart disease, a scientist at Case Western Reserve University experimented with new foods to improve gorilla’s health. She first created a primate mass index (PMI) to measure how overweight gorillas were.

Then she put the gorillas on a more wild type diet comprised of lettuce, dandelion greens, alfalfa, green beans, flax seeds and bananas.

Natural Vs Unnatural Eating

The wild type diet took much longer to eat, mimicking their natural foraging time. It reduced regurgitation and reingestion behavior that was a problem with the biscuit diet, as well as nervous hair plucking behavior. Blood serum collected before and after the diet showed reduced insulin and cholesterol levels.

Even though future research is needed to determine if there is a link among zoo diets, obesity, and the development of heart disease, a more wild type diet improved the health of zoo gorillas. It appears that a healthy gorilla is a gorilla gone wild.

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