Top 10: Medicines for Weight Loss

The runaway demand for weight loss drugs is not only reshaping the pharmaceutical landscape, it is also a reflection of a worrying global trend: billions of people are getting older, and fatter.

According to The World Obesity Federation –  the only global organisation focused exclusively on obesity – nearly 40% of the world’s population is overweight or obese. By 2035 this is forecast to increase to 51%, or more than 4 billion people.

New diabetes and weight-loss drugs are proving effective at helping people shed as much as 20% of their body weight. 

Celebrity endorsements fuelling weight loss market

The commercial success of modern weight loss treatrments has been fuelled by celebrity endorsements, notably from Oprah Winfrey and Elon Musk. Their influence has seen the weight loss drug Wegovy help its Danish manufacturer Novo Nordisk overtake the French luxury group LVMH as Europe’s most valuable company. Its current market value is US$429bn, making it worth more than the entire Danish economy. Demand is so buoyant Novo Nordisk is struggling to keep up with orders and is scrambling to expand production sites.

The success of Novo Nordisk and other pharmaceutical companies who have weight loss offerings is going only in one direction: up. According to Goldman Sachs Research, in 2023 the global market for anti-obesity medications (AOMs) reached $6bn, and by 2030 is, astonishingly, expected to grow by a factor of 16, to $100bn.

The US is the largest single market for AOMs. Last year, an estimated 8.2 million prescriptions for them were written – quadruple the number in 2021. 

But it is not just the US that is seeing an epidemic of obesity; it is a similar story in countries throughout the developed world. 

In the UK, for example, recent data from the National Health Service shows hospital admissions for obesity-related conditions have doubled in the past six years, and are now twice those of smoking-related health issues.

How do weight loss drugs work?

To date, six diabetes and weight loss treatments have been approved by the US Federal Drugs Administration (FDA) for long-term use (drug brand names in brackets:

• Bupropion-naltrexone (Contrave)
• Liraglutide (Saxenda)
• Orlistat (Xenical, Alli)
• Phentermine-topiramate (Qsymia)
• Setmelanotide (Imcivree)
• Semaglutide (Wegovy)

Almost 2 million people in the US were taking semaglutide medications in 2021 – more than three times as many as in 2019.

Most weight loss medications are based on peptides – short chains of amino acids that are the building blocks of skin proteins such as collagen, elastin and keratin. 

Certain peptides also boost levels of insulin production, which helps to maintain muscle mass while losing body fat. Used in weight loss medicines, peptides work by mimicking a hormone produced in the gut called GLP-1, which regulates blood sugar and tells the brain when a person is full. 

Such drugs require a prescription from a doctor and are administered by injection, typically once a week, or are taken orally.

Other classes of weight loss drugs are based on amphetamines, which  increase heart rate and blood pressure but decrease appetite. 

What are the most popular weight loss medicines?

Here, we include ten of the most popular weight loss medicines, many of which were developed to help treat type-2 diabetes. 

01. Wegovy

Drug: Wegovy
Active ingredient: Semaglutide
Company: Novo Nordisk
Country: Denmark
As already mentioned, Novo Nordisk’s Wegovy has taken the world by storm. It was approved by the FDA in 2021 for use in obese adults and children aged 12 years and above. Wegovy is administered once weekly via a pre-filled injection pen. Ozempic is the same medication but is approved to treat type 2 diabetes.

02. Zepbound

Drug: Zepbound
Active ingredient: Tirzepatide
Company: Eli Lilly
Country: US
Tirzepatide was previously approved to treat type 2 diabetes as Mounjaro. As Zepbound, it is approved to treat obesity in adults with a BMI of 30 or greater. It works by activating two hormone receptors to  reduce appetite and food intake.

03. Saxenda

Drug: Saxenda
Active ingredient: Liraglutide
Company: Novo Nordisk
Country: Denmark
Saxenda is an anti-diabetic medication used to treat type 2 diabetes, and chronic obesity. Last year, Novo Nordisk warned that demand was outstripping supply of Saxenda, and that clinicians may struggle to get hold of it.

04. Adipex

Drug: Adipex
Active ingredient: Phentermine
Company: Teva Pharmaceuticals
Country: Israel
Taken orally, Adipex is a medication used in conjunction with diet and exercise to treat obesity. It is taken for up to a few weeks at a time, after which the benefits taper off. It is available in both tablet and capsule form. The medication was developed by Gate Pharmaceuticals, which is now part of Teva Pharmaceuticals

05. Qysmia

Drug: Qysmia
Active ingredient: Phentermine-topiramate
Company: Vivus Medical
Country: US
Qysmia is one of the most prescribed branded oral weight-management medications for adults in the US, and is now also FDA-approved for weight management in children ages 12-17. The once-a-day pill is available only through mail order, a move designed to regulate its prescription, because of side effects. 

06. Xenical

Drug: Xenical
Active ingredient: Orlistat
Company: Roche
Country: Switzerland
Xenical is the brand name given to the orlistat-based medication by its manufacturer, Roche. Xenical can be prescribed to patients with a BMI of more than 30.  Its primary function is preventing the absorption of fats by acting as a lipase inhibitor, thereby reducing caloric intake.

07. Imcivree

Drug: Imcivree
Active ingredient: Setmelanotide
Company: Rhythm Pharmaceuticals
Country: US
Imcivree is used for the treatment of obesity, but also is prescribed to sufferers of Bardet Biedl syndrome (BBS), a rare genetic condition that can cause both blindness and substantial weight gain. Imcivree controls the form of hunger associated with BBS. It is used in adults and children aged six and older. 

08. Tepanil

Drug: Tepanil
Active ingredient: Diethylpropion hydrochloride
Company: Eli Lilly
Country: US
This medication is an appetite suppressant and belongs to a class of drugs called sympathomimetic amines. It is used in the short-term management of obesity, in conjunction with with dietary and lifestyle changes.

09. Contrave

Drug: Contrave
Active ingredient: Bupropion-naltrexone
Company: Orexigen Therapeutics
Country: US
Contrave is a fixed-dose combination medication for the management of chronic obesity in adults in combination with a reduced-calorie diet and increased physical activity. It is FDA-approved for people who are overweight with at least one serious medical condition including diabetes and high blood pressure.

10. Lomaira

Drug: Lomaira
Active ingredient: Phentermine hydrochloride
Company: KVK-Tech
Country: US
Lomaira is a type of amphetamine that increases heart rate and blood pressure but decreases appetite. Taken orally, it is used in the short-term as an appetite suppressant in conjunction with lifestyle changes to help with the management of obesity.