Tianna, 30, says the more weight she lost the larger her breasts became
A woman with 34NN breasts discovered she had a rare condition after her breasts grew bigger when she started taking Mounjaro. Tianna Moon, 30, suffers from gigantomastia – a rare condition which causes rapid breast tissue growth.
She has “always” had a larger chest and decided to lose weight using Mounjaro in May 2024. She lost three stone but found it “odd” when her breasts grew from an L cup to an M cup – rather than getting smaller as she did. Tianna researched the condition online on medical discussion groups and Chat GPT and came across others who suffer from the condition, before visiting her GP in July 2025 who confirmed she had gigantomastia.
The content creator struggles to find a bra – having to buy the biggest possible size and “make it work” which leaves her with cuts and infections under her ribs. Over the last six months she has “stepped away” from trying to wear bras as they cause so much pain and she is “happier without them”.
She has since been referred for physiotherapy to help with any pain and underwent a gastric sleeve privately in November 2025 to help “protect” her back from further pain. Her breasts have since continued to grow after a further two stone weight loss to a NN cup.
Tianna, from East Anglia, said: “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 says her larger chest meant she attracted “quite a bit of attention” from people her age and older. She said: “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 her weight loss journey Tianna was 19st and has slimmed down to 14st. After finding it “odd” her breasts kept growing despite her weight loss in 2024, Tianna did her own research and discovered what gigantomastia was after “stumbling across it” researching similar condition macromastia.
Macromastia is a similar but less severe medical condition in which breasts become enlarged at a more gradual rate. In July 2025, she went to her GP. She said: “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 14st, and with 34NN boobs she Tianna is looking into breast reduction surgery but says there is “no guarantee” her breast tissue won’t grow back. Beginning her OnlyFans career in 2021 after a head injury left her unable to work full-time, Tianna now makes £10,000 a month off admirers of her fuller bust.
She said: “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 saying she is 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”.
