Ozempic and Wegovy (semaglutide) have caused a media storm after randomised controlled trials showed that participants living with obesity could lose up to 20% of their body weight after one year.
These results were unlike anything that came before it, with lifestyle interventions typically only achieving weight loss of around 5-10%.
However, the pharmaceutical company Eli Lilly has two medications, tirzepatide (Mounjaro) and retatrutide, in production that haven’t yet been approved for treating obesity and type 2 diabetes in the UK.
Recent research suggests these medications may be even more effective and are achieving weight loss beyond 20% after 48 weeks. This is likely due to the new medications mimicking multiple hormones that support appetite and blood sugar control.
Mounjaro, Ozempic, and Wegovy are GLP-1 receptor agonists, medications that reduce appetite to support weight loss and improve blood glucose control through various mechanisms.
Mounjaro – in addition to being a GLP-1 medication – is also a glucose-dependent insulinotropic polypeptide (GIP) mimetic–GIP is a hormone in the body that supports blood glucose levels and helps our fat cells store more excess energy we might consume in our diets.
So, Mounjaro has a dual function that mimics two hormones in the body that support blood glucose levels and weight loss.
A randomised controlled trial in 1897 of individuals living with type 2 diabetes compared the impact of three doses of tirzepatide (5mg, 10mg, and 15mg) compared to a once-weekly injection of 1mg semaglutide (Ozempic) on blood sugar levels.
The results showed that all three doses of tirzepatide led to more significant weight loss than 1mg of semaglutide.
No studies have yet compared Mounjaro with Wegovy directly. However, researchers have compared the impact of both drugs from different studies and suggested that the higher doses (10mg and 15mg) of tirzepatide might reduce weight by 5.15kg more than 2mg of semaglutide.
In comparison, there was no difference between 5mg of tirzepatide compared to 2mg of semaglutide. 2mg isn’t the 2.4mg dose available with Wegovy, so it remains unclear how the higher doses of Mounjaro compare to Wegovy.
Novo Nordisk manufactures Ozempic, while Mounjaro is by Eli Lilly. The active ingredient in Mounjaro is tirzepatide, and semaglutide in Ozempic.
Mounjaro and Wegovy are approved for individuals living with type 2 diabetes in the U.S., while Wegovy is approved for weight loss.
They were initially approved as prescription drugs but are now widely available online for private purchase.
Ozempic is available in the UK, but Mounjaro is still seeking approval, which is expected towards the end of 2023 or 2024.
Retatrutide (no brand name – Eli Lilly)
Retatrutide is a triple-hormone-receptor agonist that mimics the hormones GLP-1, GIP, and glucagon.
GLP-1 acts on the brain to reduce food-seeking behaviours and appetite. It also affects the gut and pancreas to manage blood sugar levels.
GIP supports blood sugar control and helps our fat cells absorb more energy when we consume excess energy.
Glucagon’s primary role is to assist the body in managing blood sugar levels by interacting with the liver. It also prevents low blood sugar levels during fasting, exercise, and periods of low-carbohydrate intake.
The triple action of retatrutide on these hormones is likely why a recent randomised controlled trial showed that 100% of participants lost more than 5% of their body weight, with an average weight loss of 24%.
No studies have compared retatrutide to semaglutide (Ozempic/Wegovy) or tirzepatide (Mounjaro). However, these results suggest that retatrutide may prove to be the most effective weight loss medication yet.
Retatrutide has not yet undergone phase three trials, the final phase before receiving approval from regulators. Therefore, it is unlikely to be available for another couple of years.
Take home message
This new wave of weight-loss medications shows no sign of waning. Researchers are continually testing and analysing new compounds to target the GLP-1 receptors to try and improve the drugs’ effectiveness and safety.
Semaglutide has garnered much media attention in the past year or so and has been hailed a ‘miracle drug’ by some commentators and journalists.
But we already have two drugs in production, tirzepatide and retatrutide, potentially even more effective at supporting weight loss and blood sugar levels.
It’s essential not to get too caught up in the hype surrounding these medications. Yes, they’re very effective, but not magic and won’t be appropriate for everyone.
If you’re currently living with type 2 diabetes and obesity and are considering taking GLP-1 medications, it’s best to speak with your local healthcare team about your options.
At Second Nature, we’ve launched a GLP-1-supported weight-loss programme in the UK. This programme will combine our award-winning behaviour change programme with GLP-1 medications like Ozempic and Wegovy.