A new class of drugs has become a phenomenon. GLP-1 receptor agonists, originally developed to treat type 2 diabetes, are now perhaps better known for their weight-loss potential.
A GLP-1 receptor agonist works by mimicking the action of a naturally occurring hormone in the body called glucagon-like peptide-1, or GLP-1. This hormone plays a key role in regulating blood sugar levels, appetite and digestion. GLP-1 receptor agonists are synthetic versions that bind to GLP-1 receptors and activate them for longer and more strongly than the natural hormone.
GLP-1 agonists reduce glucagon release after meals, preventing excess sugar from being released by the liver. They slow gastric emptying, which prolongs feeling full and reduces the speed at which glucose enters the bloodstream. They also bind to receptors in the brain which reduce hunger and increase satiety, making it easier to eat less.
The best known GLP-1 agonist is semaglutide (Ozempic and Wegovy). A related drug, tirzepatide (Mounjaro) has recently been authorised by the Health Products Regulatory Authority, although it should be noted that only Wegovy is licensed for weight loss here.
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Celebrities such as Sharon Osbourne and Oprah Winfrey have talked openly about how Ozempic has helped them lose weight. Tabloids and gossip sites, not content with criticising women for carrying weight, have already coined the term Ozempic face to describe those who have lost fat rapidly, especially in middle-aged or older adults, whose skin is less elastic.
Weight loss wasn’t always a cultural obsession. For much of history, carrying extra weight signified good health or wealth; people faced relatively little social pressure to stay within narrowly defined acceptable weight limits.
But by the late 19th century, attitudes shifted and being overweight was widely seen as unhealthy and undesirable. This was particularly pronounced in anglophone cultures, where the Victorian ideals of temperance, hard work and moderation dominated.
The Victorians were prone to fads. Aquariums, ferns and Egyptian mummies filled the parlours of the middle classes, as did magazine advertisements making extravagant and rather dubious claims about hydrotherapy, electricity and a variety of drugs. Quack remedies abounded: patent tonics and fat-reducing pills promised quick results with unlikely and often dangerous ingredients.
Amid a sea of dieting techniques, including chewing foods until they were liquid, avoiding acidic foods and consuming only vinegar, the idea of a pill persisted
Of these bizarre and risky slimness offerings, perhaps the most infamous was the tapeworm diet. One advertisement for WT Bridge enticed consumers with “sanitised tapeworms”. These were pills supposedly containing tapeworm eggs that, once hatched in your gut, would devour your food and allow you to lose weight without dieting, exercising or (and perhaps most concerningly) bathing.
The ad pages of 19th century periodicals were about as trustworthy as the average pop-up offering an apparently celebrity-endorsed cryptocurrency scheme (interestingly, getting rich quick seems to have overtaken weight loss in the internet scam hierarchy), and it’s unclear if anyone actually tried, much less succeeded, to acquire and use tapeworm dieting.
But the idea has persisted: no less an authority than Khloé Kardashian floated the idea in 2015. The late medical journalist Dr Michael Mosley managed to get three tapeworms into his intestines; disappointingly for quick-fix dieters he also gained a kilogram.
Amid a sea of dieting techniques, including chewing foods until they were liquid, avoiding acidic foods and consuming only vinegar, the idea of a pill persisted. Tablets laced with arsenic (mildly stimulant but highly toxic) were briefly popular, but in 1891 George Redmayne Murray successfully treated a patient with myxoedema using sheep thyroid extract. Doctors using thyroid therapy quickly spotted that it increased metabolism and began recommending its use to treat what was then known as corpulence.
Benzedrine, an amphetamine inhaler sold as a decongestant, was launched in 1934. Its stimulant properties were noted, and amphetamine became a key ingredient of pep pills, used to help students focus. In 1939, studio bosses Judy Garland on a regime of pills and chain-smoking while she was filming The Wizard of Oz to keep her unnaturally productive and thin. Cigarettes were a popular appetite suppressant: one 1920s advert cheerfully advised consumers to opt for Lucky Strikes over sweet treats.
By mid-century, diet pills were prescribed widely and often recklessly. The US Food and Drug Administration authorised Obetrol, a mix of amphetamine and methamphetamine, in 1960. Some doctors even offered rainbow pills, a heady mix of amphetamines, barbiturates, diuretics and hormones until, in 1970, amphetamines were classified as controlled substances.
More recently, potential miracle pills, such as fen-phen and sibutramine, were withdrawn over serious side effects. GLP-1 agonists have a lot of promise, and alongside treatment for diabetes could be especially useful for overweight people whose conditions make exercise difficult. Although, unlike tapeworm pill manufacturers, I still recommend bathing.
Stuart Mathieson is research manager with InterTradeIreland
