WE’VE heard how weight loss jabs can leave slimmers with some unwanted physical changes, like sagging bums and jowly faces.

But scientists have warned that the game-changing injections could bizarrely affect people’s behaviour, causing them to act recklessly and engage in risky sex or gambling.

Skinny jabs like Wegovy and Mounjaro – as well as diabetes medication Ozempic – work by mimicking a hormone produced naturally by your gut when you eat food, to slow digestion, dull hunger pangs and shed body weight.

But according to London-based researchers, the jabs could interfere with normal decision making and cause some users to act “out of character”, leading to risky sexscapades, compulsive gambling or even rash divorce filings.

They believe the jabs might be linked to a change of levels of dopamine – a brain chemical involved in feelings of pleasure and reward – could be behind these odd behavioural side effects.

A report, published in the Quarterly Journal of Medicine, suggested that weight loss be causing patients to display signs of impulse-control disorder (ICD), a group of behavioural conditions that make it difficult to control your actions or reactions.

Its authors – Professor Raymond Playford, from the University of West London, and Professor Martin Deahl, from the Institute of Psychiatry – said patients ought to be warned about these bizarre side effects and cautioned against making life-changing decisions rashly.

Prof Playford, an expert in molecular medicine, told MailOnline: “We have some patients suddenly filing for divorce or splitting up from what seemed to be stable relationships and changing their home situation such as moving house on short notice. 

“We have not seen excessive gambling or sexual activity in patients to date but we wouldn’t be surprised if this was happening.”

Speaking to The Mirror, the expert said: “Reckless decision-making due to impulsivity can have serious life-changing repercussions for the patient and their families, which in the worst cases, could result in bankruptcy, changed sexual relationships, and divorce.”

He noted that ICD is noted as a side effect of for drugs to treat Parkinson’s disease, such as Levodopa and Capergoline, as they can affect dopamine levels in the brain.

But no such warnings are included in the patient information leaflets of weight loss jabs, also known as called glucagon-like peptide-1 receptor agonists (GLP-1 RA).

Parkinson’s UK notes that Levodopa may cause impulsive or compulsive behaviours in some users, including “gambling, becoming a ‘shopaholic’, binge eating or focusing on sexual feelings and thoughts”.

As for Capergoline, the NHS warns that “a strong desire to gamble or a greatly increased sex drive” may be rare side effects from the drug.

The study authors now want doctors to warn patients taking GLP-1 medications about the possibility of displaying impulsive and rash behaviours.

Professor Playford told MailOnline: “We are advising that doctors also warn patients to look out for urges that are “out of character” or unusual with cost or personal repercussions — for instance divorce — and to “step back” and think whether this is a sensible decision.

“It may also be useful if they share the fact they are starting [drugs such as Ozempic] with a loved one or close friend, so they can give a cautionary note if they see something unusual.

“This warning should allow patients and doctors to reflect and consider whether the decisions some patients have been making are out of character and riskier than one would expect.

“If they are not aware it is a possibility then they don’t make the association.”

As popularity of weight loss jabs has increased, so have reports of bizarre side effects from the drugs.

People have claimed that the rapid weight loss fuelled by the drugs have left them with loose skin around their face and bum, while some women have paradoxically claimed that it made their breasts bigger.

Meanwhile, anecdotal evidence suggests that weight loss jabs might be leading to a baby boom, as some women using them have reported falling unexpectedly pregnant.