The disorder causes the chemical to build up in her system before it is released in her sweat, urine and breath - giving off a strong fishy odour.
Ms Graves, from South London, said: "You know when you go to the food market and there's rotting fish? That's what I smell like.
"The whiff comes out from my skin and hair. I sweat it out and it doesn't matter how many showers I take, I just can't get rid of it.
"There were times when I smelt so badly of fish that my mum wouldn't let me go to school because she didn't want me to be bullied by the other kids.
"And it's hardly ideal to have to go on stage and give a performance when you stink of fish!"
She is unable to smell her own odour and has to rely on friends and family to tell her.
"The fact that I can't sniff it out myself is the most frustrating thing about the disorder. It makes you paranoid," she said.
Ms Graves's unpleasant smell was first noticeable when she was three years old, her sister first picking up on it.
"I used to share my bedroom with my sister and she started complaining about how much I stank of fish," Ms Graves said.
"My mum presumed she was just being the standard grumpy older sibling and ignored her. However gradually, the smell became so strong that no-one could deny it."
She saw several doctors but none could explain the reason for her fishy odour.
It was only after Ms Graves' mother listened to a radio show about someone with fish odour syndrome, that she was finally diagnosed with the condition.
Ms Graves began to identify the foods that were directly causing her smell and as a result she has cut out fish, meat and dark green leafy vegetables out of her diet.
"Eliminating those foods was devastating. As a child, fish fingers were my favourite food," said Ms Graves.
"Over the years, I've tried to re-introduce small amounts of fish into my diet again to see if I had grown out of it. But each time, I wake up the next morning and my whole bedroom reeks of fish."
The singer-songwriter says that living with Trimethylaminuria is a daily struggle.
"Even now, it's hard explaining to others that I have fish odour syndrome," she added.
It's so rare that people don't believe you when you say you have it.
"At gigs, I feel like a right diva asking that they don't serve certain food.
"Reputation is everything in the music business and I don't want people regarding me as ungrateful. I know I'm not Mariah Carey!"
One person who is supportive of Ms Graves's disorder is her boyfriend, Dom Oliver, a 21-year-old student.
"I'm so fortunate that Dom is cool about the smell and doesn't find me gross," she said.
"He helps me with my restricted diet. We also have a pact that if I stink of fish in the morning, he'll tell me immediately and try not to laugh.
"I'm lucky I've found a boy who has a sense of humour about it. Dom's family have accepted me with it too - in fact, his dad often make jokes about me smelling!"
However, Ms Graves admits that her condition has led to some embarrassing moments during their relationship.
"For Valentine's Day, Dom treated me to a lovely meal at a posh restaurant. I was swept away by the whole occasion and stupidly, I thought I'd treat myself and try some seafood," she said.
"Later during that evening, I absolutely stank of fish - not romantic at all."
Ms Graves, who is currently working on her first solo album wants to educate more people about the disorder.
"I've got to a point where I don't want to hide it anymore. It's a tricky thing to admit that 'Yeah, I stink' but at the end of the day, there are worse things in life than smelling of fish," she said.
"Fellow sufferers need to be more open and talk about their experiences."
Dr Robin Lachmann, a consultant in Metabolic Medicine at University College Hospital in London, said: "Trimethylaminuria is still very much under-recognised and a lot of doctors aren't aware of the condition.
"As a result, it takes a long time for patients to be referred to a specialist and diagnosed.
"Treatment is a diet low in trimethylamine, which is found in fish and choline, which is found in foods like red meat and eggs."
What is trimethylaminuria?
Trimethylaminuria is an uncommon genetic disorder that causes a strong body odour usually described as like rotting fish, faeces or rubbish.
The smell is created when the body is not able to break down trimethylamine - a smelly chemical that is produced in the gut - particularly when protein and choline-rich foods are digested, such as meat and eggs.
The chemical trimethylamine builds up the body and sufferers of the condition give off a strong odour in their sweat, urine and breath.
Usually the smell first becomes apparent in childhood when children first eat food responsible for the odour. Sometimes the disorder is temporary.
Typically people with the disorder typically avoid eggs, dark green vegetables such as broccoli and peas, beans, seafood and oily fish.
Low doses of antibiotics can suppress the production of trimethylamine in the short term and supplements can help, but lifestyle changes are mostly used to treat trimethylaminuria.
- Daily Mail
