'I find it hard to accept that I've got
a fat memory of over 12 stone'

Age 15: Gayna says: "I did the 'hip and thigh diet'. I was never a skinny child, but over the previous couple of years I had gained about a stone, taking me up to 10st 7lbs - quite heavy for my height at 5ft 5ins. I lost half a stone but I was hugely disappointed when it went straight back on."

Age 15-22: "Over the next seven years I gained 3st and went up to 12st 13lbs by the time I was 22. So I joined Weight Watchers and lost 2st. But over Christmas I put on half a stone, even though I was careful."

Age 22-25: Disheartened, Gayna didn't go back to Weight Watchers and over the next three years she ballooned up to 12st 7lbs.

Age 27-28: "In the summer of 1997 my boyfriend Mark proposed and we threw a party to celebrate getting engaged. When I saw the photographs I looked huge. So I joined Slimming World, and although the weight came off slowly - about 1lb a week - I stuck with it. By my wedding day in October 1998 I was thrilled to be just 9st 12lbs, my lowest-ever. We went to Barbados on honeymoon, which was wonderful, and I was determined not to pig out. I ate mainly fish and veg with only the occasional curry, though I did drink some beer after being teetotal for eight months. But I could not believe it when we got home and I discovered I'd gained a stone in a fortnight - almost half the weight it had taken me eight months to lose."

Age 28-29: "Although I continued to eat healthily, by October 1999 I was 11st 5lbs. So I joined another Slimming World class and by Christmas was down to 10st 9lbs."

Age 30-31: In June 2000, Gayna found she was pregnant. Over the next nine months she gained 3st. Although she went down to 11st 7lbs after daughter Megan was born, by January 2002 she was back up to 12st 9lbs.

She says: "I was told I'd probably lose lots of weight breast-feeding, but found myself snacking on biscuits to give me energy and gained over a stone. So I rejoined Slimming World. While I managed to lose a stone in three months, I then started to gain weight even while following the plan. I can only imagine this was the effect yo-yo dieting had had on my metabolism."

Age 32: Gayna was 12st when, in June this year, she signed up for a new weight-loss programme called Immogenics. It involved having blood tests to see which foods she was intolerant to.

The diet is based on the principle that these foods were making her fat because, instead of breaking them down, her body was using all its energy to fight what it considered a dangerous foreign body. She was told to cut out chocolate, wheat, oats, barley and gluten as well as pepper, lettuce egg yolk and trout.

Within eight weeks Gayna had lost 11lbs and now weighs 11st.

She says: "I'm convinced my body has a fat memory. It explains why my weight climbs back up so quickly as soon as I come off a diet. What I find hard to accept, though, is that my 'natural weight is 12st. I'm hoping now that I can trick it into allowing me to stay at a much lower weight."