Is the ‘Godzilla’ weight loss shot REALLY the best? MailOnline’s image reveals all… and how it really compares to rivals Ozempic and Mounjaro

A new weight loss jab nicknamed ‘Godzilla’ could be the best yet, research has suggested.

Exciting trials of the drug retatrutide showed it helped people lose a quarter of their body weight in less than a year.

Unlike other weight loss injections, retatrutide not only suppresses appetite, but also speeds up metabolism.

But is this the most effective? A fascinating MailOnline image shows exactly how it compares to its rivals.

Semaglutide

Semaglutide, sold under the brand names Ozempic and Wegovy, mimics a hormone called GLP-1 that makes people feel full.

Ozempic is currently only available on the NHS for managing blood sugar levels in type 2 diabetes patients.

Due to the dramatic slimming effects demonstrated in studies and real-world scenarios, doctors and pharmacists have distributed it ‘off-label’ to people who want to lose weight.

However, health chiefs have repeatedly urged against this due to supply issues, warning it would put the lives of diabetics at risk.

Wegovy, packed with the same active ingredient, was approved last year specifically for weight loss. Although the country is also affected by global shortages.

Studies crucial to getting Novo Nordisk’s semaglutide approved show it can help users lose up to 15 percent of their body weight in 68 weeks.

A month’s supply is available privately from Boots and Superdrug for around £200.

The eligibility criteria for people wanting to get the drug on the NHS – at the standard prescription rate of £9.90 in England – is strict.

And the medications are not without side effects.

Users often complain of nausea, constipation and diarrhea after taking the medication.

Tirzepatide

Mounjaro, as it is called, also mimics GLP-1, as well as a second appetite-controlling hormone called GIP.

Research has shown that the drug, made by US pharmaceutical giant Eli Lilly, can help obese people lose up to 22.5 percent of their body weight in 72 weeks.

Like semaglutide, it is self-injected once a week.

The stark difference in results prompted American diabetes expert Dr Julio Rosenstock to declare Mounjaro ‘King Kong’ compared to ‘the gorilla’ of his rival Wegovy.

Some patients already taking the drug have shared their results on social media, with one overweight man claiming it helped him lose 45.4kg.

As with semaglutide, side effects of tirzepatide (Mounjaro’s generic name) include nausea, diarrhea, vomiting – which usually goes away with time – and constipation.

It was given the green light by the National Institute for Health and Care Excellence (Nice). NHS use in September for patients with type 2 diabetes who cannot control the condition.

It is not yet used by the healthcare system for obesity.

But in February it was made available privately in Britain, with clinics charging around £40 for a week’s supply.

Retatrutide

Retatrutide, meanwhile, adds a third hormone called glucagon, which prompts the body to burn more fat, increasing calorie burn.

Trial results, presented yesterday at the European Obesity Congress in Venice, showed it achieved an even greater average weight loss – 24 percent of body weight – over a shorter period of 48 weeks.

The phase two study of 338 obese people also found that results were even starker in women, with them losing 28.5 percent of their body weight.

By comparison, men lost an average of 21.2 percent.

And more obese participants lost an even greater percentage of their body weight: 26.5 percent in 48 weeks.

Unusually, 100 percent of trial participants lost at least 5 percent.

Like all previous GLP-1 medicines, retatrutide – taken once a week – can has led to side effects such as nausea, diarrhea and constipation.

But the study, published in the New England Journal of Medicine, shows that the drug also had other health benefits.

Participants saw significant improvements in blood pressure and blood sugar levels. Four in ten participants were able to stop taking high blood pressure medications.

Manufactured by US pharmaceutical company Eli Lilly, larger studies are now underway and results are expected in 2026.

It means the treatment could be available on the NHS in around three years, pending the final regulatory hurdles.

Orlistat

Orlistat is a pill already available on the NHS for weight loss.

When taken up to three times a day with a meal, it prevents fat from being absorbed by the digestive system.

The undigested fat is instead excreted from the body as feces.

While this keeps people from gaining weight, it doesn’t help them lose the weight on their own.

Side effects include greasy or oily poop, oily discharge from the rectum, and high levels of flatulence.

Manufactured by pharmaceutical giant Roche, early studies suggest patients taking 120mg could lose up to 10.3kg in 52 weeks.

Its prescription by the NHS is restricted to people who are obese or overweight and have another health problem such as high blood pressure.

Liraglutide

The daily, self-administered shot, sold under the brand name Saxenda, is another weight loss treatment already available in healthcare settings.

It works in a similar way to semaglutide by changing the body’s metabolism, making people feel fuller and less hungry.

This leads to them eating less and, in theory, losing weight.

However, Saxenda is one of a number of similar drugs suffering from a global supply shortage.

Liraglutide is generally only prescribed on the NHS after a GP has referred you to a specialist weight loss service and when orlistat has not worked.

Side effects include pain, diarrhea, fever, frequent urination and difficulty sleeping.

Tests manufactured by Novo Nordisk have shown that users lose an average of 6.4 percent of their body weight in 68 weeks.