A woman was left baffled after her breasts ballooned in size despite her shedding five stone with the help of Mounjaro.
Tianna Moon, 30, is now considering breast reduction surgery to reduce the size of her 34NN bust - but said there is 'no guarantee' that it will stop them growing back.
Patients seeking to undergo this procedure on the NHS must meet a strict criteria before they get the green light and are often advised to try losing weight before going under the knife.
To qualify, your ample bosom must be causing you back, shoulder or neck pain, skin irritation, grooves on the shoulders from bra straps, low self-esteem or depression and stopping you from exercising.
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Brits also need a Body Mass Index (BMI) score of less than 26, 'with an anticipated volume reduction of 500 grams', to gain approval for breast reduction surgery on the UK's health service.
Tianna was 19 stone when she decided to try and shed some weight in May 2024 due the ever-growing size of her breasts, as she explained bras became 'impossible' as the size she needs 'don't exist'.
Instead, she was forced to buy the biggest possible size and 'make it work', which she says left her with cuts and infections under her ribs.
Tianna explained she has 'always' had a larger chest and that this can attract a lot of unwanted attention, but she's now become so used to people gawping at her that she 'doesn't notice it anymore'.
"When I go out in public I try and make then smaller than they are and strap them up," she added. "I get the odd stares and double takes."
Nearly two years ago, she started taking the weight-loss drug Mounjaro and Tianna managed to lose three stone over the course of 12 months, before later shedding another two stone.
Although her waistline grew smaller, her breasts continued to swell in size and she shot up from an L cup to an M cup, which she found 'odd'.
Explaining what life is like with such a voluptuous chest, Tianna said: "The side effects are like having numb arms quite a lot and having quite severe indentations on my shoulders.
"I have some light scarring under my breasts where bras have rubbed and ripped the skin open. Also, laying on my back is not something I can do for a long period of time, as it restricts the amount of air flow I can get in."
The 30-year-old, from East Anglia, ended up visiting her GP in July last year after conducting some of her own research into why her boobs might still be growing.
Her doctor then confirmed that she has gigantomastia, a rare condition which causes the rapid growth of breast tissue. You can watch Tianna discuss her gigantomastia diagnosis here:
"When I broke down medical history, the weight loss on Mounjaro and the increased growth and side effects, he was point blank like ‘this is gigantomastia’," Tianna said of receiving the diagnosis.
"I got the diagnosis quite early because of the growth not being common with anything else. At that point I decided to get rid of the extra weight and protect my back because of the diagnosis."
According to the Cleveland Clinic, although the causes of it aren't confirmed, health experts believe it can be triggered by hormonal changes, certain medications, autoimmune conditions, extreme obesity or genetics.
In wake of her diagnosis, Tianna was referred for physiotherapy to help with any pain and underwent a gastric sleeve privately in November 2025 to help 'protect' her back and 'prevent future pain'.
She is looking into undergoing breast reduction surgery now, but has been told there is 'no guarantee' that her boobs won't grow back.
Tianna decided to make the best out of her situation in 2021 by joining OnlyFans after a head injury left her unable to work full-time - and her breasts have proved very popular with her subscribers.
She claims to make up to £10,000 a month on the website and revealed that one of her admirers actually encouraged her to dig deeper into why her chest was growing despite her weight loss.
"I might as well try and reap the benefits of my medical condition rather than the negatives," Tianna said. "As [my breasts] got bigger, it was actually a subscriber who said, 'You need to get remeasured because you are not the size say you are'. That’s when I started monitoring them."
Olivia Burke