The reality TV star – whose weight has fluctuated over the years – hated being criticised for being heavier than the average celebrity but refused to make herself ill by conforming to the media’s idea of beauty.

Kelly - who has recently gone down three dress sizes after appearing in last year’s ‘Dancing with the Stars‘ – said: ‘There’s nothing that can affect a woman more than the three letter word – fat. It leaves you so deflated. Being criticised for my weight made me feel I was unworthy.

‘I’ve sat in bed at night and thought, ‘Why the f**k does anyone care how much I weigh?’ I’m just one of those celebrities who has a normal-looking body. I’m not fat, I’m not skinny. I’m healthy and my body has a nice shape. I wasn’t going to make myself ill getting thin.’

Kelly, 25, says she has always had self-confidence issues but they are now improving following losing weight and finding love with fiance Luke Worrell.

She told the Stylist magazine: ‘Growing up, although I appeared to be incredibly confident, my self-esteem was terrible. I used to stand in front of the mirror and pick out everything I didn’t like, but that’s now shifting slightly.’

The 23-year-old star – who has appeared at several New York Fashion Week events looking super-slender – has revealed her top diet tip to anyone looking to get in shape.

She said: ‘A trick I’ve learned is to eat just a little bit of something that has no carbs and no sugar in it before you go to sleep because it keeps your metabolism going. They say you should never eat before you go to bed, but I’ve found just having a tiny little snack – like half an apple or something like that – before you go to sleep really helps.’

Kelly also credits her appearance on US TV talent show ‘Dancing with the Stars’ for changing her entire attitude to food and exercise.

She told America’s Life and Style magazine: ‘I’ve completely changed the way I eat since doing ‘Dancing with the Stars’.’

Kelly – who is engaged to 20-year-old model Luke Worrall – also regularly does Pilates to stay in shape.

She said: ‘Pilates is amazing, my posture is so much better and I’m even starting to get muscles on my tummy – it’s incredible.’