Ozempic vs ‘King Kong’! Scientists test famed weight loss jab against newcomer Mounjaro head to head in study of 20,000 slimmers… so who came out on top?

Mounjaro, dubbed the ‘King Kong’ of new generation of weight loss jabs has beaten its rival Ozempic in a head-to-head battle of blasting bulging waists.

American scientists pit the two drugs, which work by mimicking a hormone that makes people feel full, in a study of more than 18,000 adults who took one of the weekly injections for up to a year. 

At the end of study, patients taking tirzepatide, the ingredient in Mounjaro, were 224 per cent more likely to have lost about a sixth of their body weight than those on Ozempic. 

People on Mounjaro, made by US pharma giant Eli Lilly, also lost up to 7 per cent more weight on average than those on semaglutide, the ingredient in Ozempic. 

Researchers also found there was no increased risk of adverse side effects like diarrhoea between the two medications.

American scientists pit Ozempic and Mounjaro head to head in a study of more than 18,000 adults who took one of the weekly injections for up to a year

By weight loss goals Mounjaro was the clear winner with 82 per cent of patients losing at least 5 per cent of their total weight compared to 66 per cent in the Ozempic cohort

These charts show the different probability of patients reaching weight loss goals in either Mounjaro (green line) or Ozempic (yellow line) over the course of the study

In the study, published in the journal JAMA Internal Medicine, experts compared health data from two cohorts of adult patients with type 2 diabetes taking the jabs for up to a year. 

Of the 18,386 patients, half took Mounjaro, and the other half took Ozempic. 

Patients had similar starting weights with those in the Mounjaro cohort weighing in at 110kg (about 17st 4lbs) and the Ozempic group a slightly lighter 109kg (17st 1lb).

Researchers compared how likely each group was to hit certain weight loss goals as well as how much weight they lost, on average, at certain time periods in the study.

By weight loss goals Mounjaro was the clear winner with 82 per cent of patients losing at least 5 per cent of their total weight compared to 66 per cent in the Ozempic cohort.

About 60 per cent of Mounjaro patients lost 10 per cent of their body weight compared to just under 40 per cent of Ozempic patients. 

Finally, some 42 per cent of Mounjaro patients lost 15 per cent of their body weight compared to just 18 per cent of those on Ozempic.

The researchers said this equated to a 76 per cent increased chance that patients on  Mounjaro would hit the 5 per cent weight loss goal, an 84 per cent increased chance they’d lose 10 per cent of their starting weight, and a whopping 224 per cent increased odds of them losing 15 per cent or more.

Mounjaro was also the clear leader when it came to average weight lost over the course of the study looking at three-month, six-month and one-year intervals.

Experts found people on Mounjaro , on average, lost 2.4 per cent, 4.3 per cent and 6.9 per cent more weight respectively at these points compared to those on Ozempic. 

Despite the increased weight loss seen in the Mounjaro group scientists found no difference in reported gastrointestinal side effects, which includes diarrhoea and vomiting, between the two drugs. 

The authors concluded:  ‘In this large, propensity-matched, cohort study, individuals with overweight or obesity treated with tirzepatide were significantly more likely to achieve clinically meaningful weight loss and larger reductions in body weight compared with those treated with semaglutide.’

However, researchers noted that their findings only looked at patients with type 2  diabetes taking the drugs as part of managing their weight.

Both drugs are also now available to obese people without type 2 diabetes, though the semaglutide version for this purpose is sold under a different name, Wegovy.

Researchers said it would be interesting to see the results of a head-to-head comparison in obese patients only and noted such a study is currently underway and expected to publish results later this year. 

The experts, who hailed from the US health data company Truveta, added that one limitation of the study was they couldn’t account for participants’ own motivation for weight-loss.

This could mean, for example, some participants undertaking additional weight-loss measures like diet and exercise which may have influenced the results. 

Secondly as both of the jabs are typically administered by patients at home some may have not followed the correct dosage regime, another factor that could influence results. 

Both Mounjaro as well as Ozempic and Wegovy are now available in Britain and the US.

Ozempic and Wegovy work by mimicking one hormone called GLP-1 while Mounjaro also does this but additionally mimics another hormone called GIP. GIP is believed to enhance the effect of GLP-1.

Another difference is that Mounjaro is typically given at a higher does than its rival jab, another factor that could explain the results. 

Wegovy and Ozempic work by triggering the body to produce a hormone called GLP-1 that is released naturally from the intestines after meals

According to the latest data digestive problems were the most commonly reported side effects of tirzepatide, the active ingredient of Mounjaro. These included about one in five participants suffering from nausea and diarrhoea, and about one in 10 reporting vomiting or diarrhoea

Fat-melting jabs like Mounjaro and Ozempic have been hailed on both sides of the Atlantic as way to combat the scourge of obesity which is increasingly blighting the lives of millions of Brits and Americans.

However, some studies have suggested they also have a suite of other benefits including slashing the risk of heart attack and stroke and kidney disease, and recently even some cancers. 

Some experts have even said they should be dished out proactively to some patients, similar to statins, in a bid to curb cardiovascular disease. 

However, the jabs have been linked to host of side effects, which like any medication, vary in both frequency and severity. 

Reported problems include nausea, constipation, diarrhoea, fatigue, stomach pain, headaches and dizziness. 

Bizarre symptoms, such as hair loss, have also been reported among some patients.

Ministers in Britain plan to dole the drug to millions of overweight Brits to trim both the country’s bulging benefits bill from sick Brits taking time off work and the expanding cost of treating excess flab to the NHS.

Latest NHS data shows 26 per cent of adults in England are obese and a further 38 per cent are overweight but not obese. In the US an estimated 41.9 per cent of adult population are obese.

Britain’s expanded waistlines are also estimated to cost the nation nearly £100billion per year. 

This colossal figure includes both NHS treatment as well as secondary economic effects like lost earnings from people taking time off work. 

Despite the hormone mimicking jabs being designed to help overweight patients become healthier there have also been growing concerns about the number of normal weight and underweight patients taking them for cosmetic reasons. 

Some have even needed A&E care after taking jabs in a bid to become ‘beach body ready’. 

Young women in particular are believed to be obtaining Wegovy via online pharmacies, who offer them at between £150 to £200 ($200-$250) per month, after providing false information about their appearance and health. 

In some cases, people taking the jabs without legitimate medical cause are thought to be doing so as a result of eating disorders. 

Spiking global demand for the jabs, including amongst those taking it for cosmetic reasons, has led to some diabetes patients struggling to access supplies. 

It has also led to pharma giant Novo Nordisk, which makes Ozempic and Wegovy, to enjoy a massive boom in profits. 

Earlier this year the Danish firm revealed it was making £32million per day, as countries grappling with the financial cost of flab fight to get their hands on the jabs.

Analysis suggests that combined sales of the company’s Ozempic and Wegovy brands generated it £20.5 billion this year. 

Other drugs which work on a similar mechanism to Mounjaro and Ozempic, such as retatrutide which is also made by Eli Lilly, are also in the pipeline.