Tianna Moon, 30, lost three stone on weight loss medication but her breasts kept growing – caused by a rare condition. She has now given up wearing bras due to the pain they cause and says she is much “happier without them”
A woman with a whopping 34NN bust size discovered she had a rare condition when her breasts wouldn’t stop growing while on Mounjaro.
Tianna Moon, 30, is afflicted by gigantomastia – a rare condition that triggers rapid growth of breast tissue. She’s “always” been well-endowed and embarked on a weight loss journey using Mounjaro in May 2024. Despite shedding three stone, she found her breasts ballooned from an L cup to an M cup – instead of shrinking as the rest of her body did.
Tianna turned to online medical discussion groups and Chat GPT for answers, where she encountered others suffering from the same condition. A visit to her GP in July 2025 confirmed her suspicions – she indeed had gigantomastia. The content creator faces a constant struggle to find bras that fit – resorting to buying the largest available size and “making it work,” which often results in cuts and infections under her ribs.
Over the past six months, she has decided to “step away” from wearing bras due to the immense discomfort they cause, finding herself “happier without them”. She has since been referred for physiotherapy to manage the pain and underwent a private gastric sleeve procedure in November 2025 to help “protect” her back from further strain.
Despite losing another two stone, her breasts have continued to grow, now reaching a staggering NN cup size. Tianna, hailing from East Anglia, lamented: “Bras are impossible.
“Bras in my size NN don’t exist. I decided to lose weight and eventually started on Mounjaro and lost three stone over the course of a year.”
“In that time my breasts grew from an L cup to an M cup. 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.”
Growing up, Tianna admits her larger bust size drew “quite a bit of attention” from people her age and older. She recalled: “I remember walking home from school as a 13, 14-year-old and it was quite common to have grown men leering at me and honking their horns and stuff.
“It got to the point where last September I was in Amsterdam for the Xbiz awards as I was nominated. I was walking around with another lady and she said, ‘don’t you know realise those people are pointing at you and trying to get your attention?’ It’s become so normal to me I don’t notice it anymore”
Before embarking on her weight loss journey, Tianna weighed 19st and has since slimmed down to 14st. After finding it “odd” that her breasts continued to grow despite her weight loss in 2024, Tianna conducted her own research. She discovered gigantomastia after “stumbling across it” while researching the similar condition macromastia.
Macromastia is a comparable but less severe medical condition where breasts enlarge at a more gradual rate. In July 2025, she consulted her GP.
She explained: “Originally he was looking at macromastia but 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’.
“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.
“I attempted to weight my breasts the other day but I don’t know how reliable it is as I had to use normal scales. One of them weighed 1st 13lb and the other weighed 1st 12lb but I can’t say how accurate it is. I do suffer more with my shoulders and ribs underneath but the gastric sleeve was to prevent future pain.”
Now weighing 14st with 34NN breasts, Tianna is considering breast reduction surgery but warns there’s “no guarantee” her breast tissue won’t regrow. After launching her adult career venture in 2021 following a head injury that prevented full-time employment, Tianna now earns £10,000 monthly from fans of her chest.
She revealed: “I might as well try and reap the benefits of my medical condition rather than the negatives. After Covid and furlough I decided I wanted to work for myself and be in charge, manage my own schedule and still make money. When I first started – I’ve had a lot of growth since I first started.
“As they 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 stared monitoring them.”
“Income varies month to month 10,000 as an average is a decent month”.
Online, Tianna receives a “crazy amount” of comments from people accusing her of lying about her condition. She said: “People are telling me it’s disgusting I’m not having a reduction and that I’m basically begging for attention. People are telling me I’m lying about my diagnosis and that they don’t look absolutely humungous.
“When I go out in public I try and make then smaller than they are and strap them up – I get the odd stares and double takes,” she added.