A hormone expert has revealed a bizarre side-effect of weight loss jabs: they might send your sex drive soaring.

Originally developed for diabetes, blockbuster drugs like Mounjaro are now famed for helping users shed weight rapidly by suppressing appetite. 

But it seems they may also be fuelling a surge in libido.

Dr Shashi Prasad, a GP and expert in women's health at The Marion Gluck Clinic, said while side-effects such as nausea and even organ damage have been widely reported, changes in sexual desire remain less understood.

'Sexual desire is such an important aspect of somebody's well-being and this is still a relatively new treatment,' she said.

'We are increasingly finding that it's having an impact on people's libido—and it's not all to do with self-esteem.'

Dr Prasad explained that one possible reason for the effect is that body fat causes chronic, low-level inflammation—a key factor behind many obesity-related health issues, including reduced sex drive.

Mounjaro works by mimicking a gut hormone called GLP-1, which is released after eating to regulate blood sugar and suppress hunger.

As well as signalling the pancreas to produce more insulin, GLP-1 tricks the body into thinking it is full—stopping patients from overeating and triggering weight loss.

More than 1.5 million patients in the UK are now paying for private Mounjaro prescriptions, as well as a similar drug called Wegovy.

Some notice a change in their drinking habits, with many saying they no longer want alcohol. 

And this may give another clue to the apparent libido-boosting effect of the jabs, according to Dr Prasad.

She explains that whilst alcohol affects the part of the brain that controls inhibition—explaining why people often feel less anxious and more confident after a drink—it can dampen sex drive.

'Alcohol is a very addiction-based behaviour,' Dr Prasad explained. 'It has a suppressive effect on our emotions, releasing inhibition which can make some people more sexually inclined.

'But, sexual desire is more than that. Remember, alcohol is a depressant, so whilst you may feel more confident after a drink, physiologically alcohol actually suppresses sexual desire.'

A change to body image and the resulting boost in confidence does also play a part, she adds. 

'We know that body image, self-esteem and confidence definitely play a huge role in sexual desire—and this psychological boost associated with weight loss is a very big element.'

But some users have reported the opposite effect—finding they want to have sex less frequently. 

This may be because the drugs suppress the production of dopamine—the feel-good chemical the brain produces in response to pleasurable experiences. 

'Our brains produce dopamine in response to anything that brings us pleasure, whether that's food, alcohol, cigarettes, socialising or sex,' says Dr Alexis Bailey, a neuropharmacologist at City St George's university in London. 

'The leading theory is that GLP-1 injections helps dampen these dopamine surges.'

According to Dr Prasad, this can cause a significant drop in sex drive, resulting in users feeling more confident in their new bodies but not wanting to have sex. 

She added that losing a lot of weight over a short period of time can also affect hormone balance, as can a restricted diet, by reducing levels of sex hormones testosterone and estrogen that are crucial for sexual desire.

Dr Prasad encouraged users to have a discussion with their doctors if they are concerned about their sex drive. 

She said: 'This should help you get to the root cause of the problem. A drop in sex drive could simply be the result of fatigue caused by being in a calorie deficit. 

'Or it could mean that your dose is too high and the drug is significantly affecting your nervous system and dopamine production.' 

Either way, Dr Prasad said: 'Make sure you're eating a balanced, nutrient-dense diet with plenty of fibre and protein and exercising regularly—this will trigger the release of endorphins and may improve sexual desire.' 

She is now urging health officials to conduct more research into this aspect of the drug, and encouraging more open and honest conversations about sex and weight loss. 

'Sexual desire is such an important aspect of someone's identity—it is very important to flag this up and encourage patients to have a discussion with their doctor.' 

Her advice comes amid growing concern over a global sex crisis—or rather, lack of sex crisis. 

One recent survey revealed more than a quarter of people living in the UK are having less sex than they used to, with one in six admitting they haven't got frisky the entire year. 

Last month, researchers at the University of Manchester, also revealed women who have sex at least once a week are the happiest in their relationships.

Their study showed that 85 per cent of women who had sex once a week described themselves as 'sexually satisfied'.

In contrast, only 17 per cent of women who had sex less than once a month reported the same level of relationship bliss.

Sex and intimacy have been linked to several health benefits, including improving the condition of your heart, reducing stress and even boosting mental health.