The fat jab that can help you lose a fifth of your weight – Tirzepatide is hailed as the 'King Kong' of anti-obesity treatment

A drug hailed the ‘King Kong’ of weight-loss jabs has been found to help slimmers lose almost a fifth of their weight.

Tirzepatide was recommended last month by the National Institute for Health and Care Excellence for people with type 2 diabetes who cannot tolerate the drug metformin.

But the once-weekly injection, which suppresses the appetite, is also seen as a major tool in the fight against obesity – leading US expert Dr Julio Rosenstock to dub the drug ‘King Kong’ compared to the ‘gorilla’ of semaglutide, another weight-loss medication.

Now a study shows tirzepatide could greatly help slimmers stay trim. 

The jab was given to 287 people who had successfully lost at least five per cent of their weight through diet and exercise – who would typically put a third of the weight back on, according to the study. 

Pictured, a pharmacist displays a box of Mounjaro, a tirzepatide injection drug

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The once-weekly injection, which suppresses the appetite, is also seen as a major tool in the fight against obesity (Stock image)

But when taking tirzepatide for a year, the slimmers lost a further 18.4 per cent of their body weight on average.

Professor Thomas Wadden, who led the study from the University of Pennsylvania, said: ‘Slimmers often hit a wall, where they cannot get beyond losing five to 10 per cent of their weight – but this drug could help them achieve substantially more.

‘We also found that the drug helped to reduce blood pressure and cholesterol level, and control blood sugar.’

The study, published in the journal Nature Medicine, and presented at ObesityWeek 2023, the annual meeting of The Obesity Society, first put 806 people on a three-month slimming programme. 

Of the 806, 579 people lost at least five per cent of their weight and were eligible to begin weekly jabs.

Researchers then compared those given tirzepatide to those given a dummy injection. 

After slimming down by changing their lifestyle then using the jab, users lost an average of 24.3 per cent of their starting body weight on average

Those on tirzepatide lost almost an additional fifth of their body weight on average, while those not given the drug gained 2.5 per cent.

The people on tirzepatide lost almost 15cm (6in) from their waistline, according to the study, which included researchers from pharmaceutical giant Eli Lilly, which manufactures tirzepatide and funded the trial.

These were the results after a year on the full dose of tirzepatide, after four months of gradually introducing the dose to try to reduce the side effects of nausea, diarrhoea and constipation. 

In total, after slimming down by changing their lifestyle, then using the jab, people lost an average of 24.3 per cent of their starting body weight on average.

But critics say those using weight-loss jabs risk side effects and may need to take them for life.