A Quick History of America’s Diet Drug Craze

It’s hard to believe America’s most recent weight-loss craze started with an endangered lizard. That’s right — Wegovy, Ozempic and Mounjaro all owe their success to something secreted by the Gila monster.

Diet crazes come and go, especially when new medications reach the market. In the 1950s and 1960s amphetamine derivatives were all the rage until concerns about drug abuse and cardiovascular risks led to a decline in their use.

In the 1990s phentermine and fenfluramine, more popularly known as the combo drug fen-phen, gained wide use until it was linked fatal pulmonary hypertension and heart valve problems and pulled from the market in 1997. (Phentermine alone is still available as a weight-loss prescription.)

But the current class of medications being used for weight loss are very different in their approach. They started with the Gila monster.

In the early 1990s, Dr. John Eng, an endocrinologist, researcher and Veteran’s Administration physician, started studying the saliva of the Gila monster, a poisonous lizard native to the Southwest, hoping to help people with type 2 diabetes better control their blood sugar.

The squat lizard, which can grow up to 22 inches long, has a hormone in its poison the scientists eventually called exendin-4. It’s similar to hunger-managing hormones humans have in their digestive tract.

A synthesized compound lasts longer than similar hormones in humans – hours instead of minutes. Initially, the new compound was used in a drug class called glucagon-like peptide-1 agonists to treat people with type 2 diabetes.

While the science has evolved, the new weight-loss drugs are inspired and similar to the original drug, Byetta or exenatide, which was approved by the FDA in 2005. While the drugs, which work generally by encouraging insulin production and slowing the digestion of food, are new and go under names like Ozempic, tirzepatide, saxenda and Wegovy, they owe their origins to the humble, but poisonous Gila monster.