She was 26, two stone overweight, depressed and unable to remember people's names.
Then TV presenter Melissa Porter discovered what was to blame - a debilitating, but treatable, thyroid condition that affects one in 50 women. Nine years later she has her mind and body back
Television presenter Melissa Porter was just 26 years old when she realised something was terribly wrong with her health.
She felt exhausted and overwhelmed by depression, while just remembering simple things like people's names became harder as her mind became increasingly foggy.
But these symptoms seemed minor to Melissa compared with her mysterious two-stone weight gain in a matter of months.
It was only when a friend pointed out the strange swelling on her neck just below the Adam's apple that she visited her GP.
He recognised the swelling as a goitre or an enlarged thyroid gland.
A blood test showed that the symptoms Melissa had been suffering were classic signs of hypothyroidism - an underactive thyroid gland.
It's a condition that is more common in women - one in 50 will develop an under or overactive thyroid, compared with one in 1,000 men, although doctors have yet to discover the reason.
Today, aged 35, Melissa could pass for a woman ten years younger and is the picture of health as she breezes into the studio, flashing the warm smile that frequently has the guests on Britain's Dream Homes eating out of her hand.
Despair: Melissa in 1999 - she had lost her enthusiasm for life
But she is the first to acknowledge that to be the energetic person viewers see on our screens, she fights an ongoing battle with this debilitating condition, with prescription drugs, diet and exercise.
"I was a marketing executive for Marks & Spencer at the time, putting in 12-hour days, six days a week," says Melissa.
"I had problems getting up in the mornings, my energy levels dropped and I just put it down to the pressures of holding down a stressful job and busy social life."
But gradually Melissa noticed that her usually happy demeanour was changing as her enthusiasm for life evaporated. She became lethargic and depressed, and her once lustrous hair became thin and brittle while her skin went dry and flaky.
More worryingly, she says, at work she had become absent-minded and increasingly forgetful.
"There were lots of small signs that something was wrong but I became really alarmed when my weight ballooned," explains Melissa.
"Over a period of three months I shot up from 2 stone to over 11 1/2 stone and at my heaviest topped 12 stone.
"I'll never forget the day I bought my first size 14 dress. I had always been a size 12. I was devastated."
As a result, her confidence waned and she became more introverted.
"Even when my boyfriend at the time said I looked sexy I was convinced he was lying - I just felt so unattractive inside."
Melissa's lowest point came one night after going into a bar with a friend and catching sight of her reflection in a mirror.
"I looked at myself in my baggy jeans and an oversized rugby shirt and was close to tears. I felt like I was losing control of my life."
On location: Melissa talks to competitors on her new show for Five
For some, the diagnosis of an actual cause to all this misery might have brought relief, but Melissa was distraught at her GP's findings.
"My parents were very anti-pill-popping and brought me up to believe that any illness could be cured by a cup of honey and lemon and a good night's sleep," she says.
"I had never even taken an aspirin. When I was told by my doctors that I'd need to be on heavy medication to control my hormones for the rest of my life, I broke down."
One symptom of hypothyroidism is infertility and Melissa was warned that she might never have children.
Thirty per cent of women with the condition fail to produce eggs, and in pregnancy there is a fourfold risk of late miscarriage as the functioning of the thyroid gland can change drastically.
The culprit in hypothyroidism is thyroxine, a hormone produced naturally by the thyroid gland to regulate the body's overall metabolic rate but which is deficient in those with the disease.
Women with hypothyroidism find that during pregnancy their thyroxine requirements increase, meaning they need more frequent checks on their thyroid function.
If they fail to maintain the correct dose of thyroxine, hormone levels can drop, causing the body to reject the baby, often in the second or third trimester.
The treatment in Melissa's case was simple - a daily dose of thyroxine, which regulated her metabolism and hormone levels, so reducing her bigger anxiety; the weight gain.
Besides taking thyroxine, Melissa also decided to drastically shake up her diet and exercise patterns.
Today she is a size 12 and weighs 10 1/2 stone, which is healthy for her 5ft 10in frame.
"It's not been easy," she says. "Thankfully, I have never been told to lose weight because I'm a presenter.
"My programmes feature real people so I have to be representative of normal women rather than super-skinny."
Melissa hired a personal trainer three times a week to put her through a rigorous cardio-routine of running and circuit-training near her home in South-West London.
She also visited a top nutritionist at London's Hale Clinic who recommended a wheat, sugar and dairy-free diet with lots of protein and vegetables and limited carbohydrates.
Combined with the regular check-ups and the daily medication, the weight dropped off, her depression began to lift and her energy levels increased.
"Looking back, I realised that I'd spent my whole adult life struggling to control my weight and must have had hypothyroidism for years.
"I come from a big, half-Italian family and much of our life was focused around the dinner table.
Positive: Melissa has become an expert at managing her symptoms and getting on with her life
"At work I sat at a desk all day and the weight had just crept on. At night I went out drinking with friends and avoided exercise completely.
"I felt like I was trapped in a body that wasn't mine. But I didn't want the thyroid problem to be my excuse to sit back and accept my body shape.
"The exercise sessions were tough but when I started to see the results I was motivated to keep going.
"I filled up on lots of chicken, fish and organic vegetables and was never hungry.
"I felt much more positive and enthusiastic about my life once my weight started to fall and it gave me back my confidence."
It was six weeks after her diagnosis that Melissa, buoyed by the transformations she'd made to her diet and exercise habit, left her marketing job and set up her own business as a property consultant.
Soon afterwards, she got her big TV break through a contact who worked for the Shopping Channel and was given her first presenting job.
From there she progressed to several primetime shows, including Escape To The Country and Britain's Dream Homes on BBC1.
A typical breakfast for Melissa consists of wheat-free toast with eggs. Lunch is a chicken salad and dinner fish and steamed vegetables.
She has cut out pasta, potatoes and bread. She snacks on organic fruit or dark chocolate and drinks the occasional glass of red wine and plenty of water.
Melissa must monitor her condition for the rest of her life, as she found out to her cost.
A few years after seeing the positive results of her new fitness and diet regime, she made the drastic decision to stop taking thyroxine for three months.
"Within weeks I had gained a stone, felt exhausted and depressed and those feelings of hopelessness returned. I realised how crucial thyroxine is to my body and I won't make that mistake again."
Melissa admits she still tires easily and suffers from lethargy and poor memory, particularly if she is on the road filming, and has to resort to a sausage roll or a sandwich because nothing else is available.
"After a long day I notice myself forgetting names or tiring faster than other people," she says.
Nevertheless, the future looks good. Melissa is now filming the new Five property show I Own Britain's Best Home, which will air next month.
She is also a patron of the British Thyroid Foundation (www. btfthyroid.org) and works to raise awareness about the condition.
And she is also determined not to use her condition as an excuse or spend her time worrying about possible fertility problems.
"I often feel terrible at work but I've become an expert at managing my symptoms and just getting on with life. Being ill has made me stronger mentally and physically.
"You can't spend your whole life worrying about what could go wrong, otherwise you'd never get round to doing anything."