Seeing my ex with a slimmer woman helped me get the body of my dreams.

It’s the moment any woman dreads – running into an ex, especially if they happen to be with a new slimmer partner.

But for Sarah Clancy a humiliating run in with a former boyfriend proved to be the best thing that ever happened to her.

Because seeing him with a much slimmer woman left her feeling so humiliated that she vowed to lose weight and has since gone from a size 16 weighing 15 stone to a super toned size six.

Now stunning brunette Sarah, 28, from London says she has a lot to thank her ex for and says she has never been happier.

She said: ‘ Of course any break up hurts but I was very self -conscious about my weight and seeing my ex with a much slimmer woman was devastating.

I convinced myself my weight must have been the reason we split  and vowed to do something about it once and for all. It the most embarrassing moment of my life but also the best thing that has ever happened to me.’

After the mortifying run in a supermarket mum of one Sarah says she didn’t even have to try very hard to stick to a diet for the first time ever.

‘Just remembering how mortified I felt seeing him with a much slimmer woman was enough to keep me out of the fridge,’ she says.

‘I suppose a part of me wanted to show him what he was missing. My appetite went from being ferocious to non-existent.

‘People talk about the heartbreak diet but it’s true. I’d never lost weight so quickly.

Sarah had gained the bulk of her weight while pregnant with her daughter.

She said: ‘ I’d always been a curvy girl but when I fell pregnant in April 2009 I started eating for two and never stopped.’

During her pregnancy 5ft 2ins Sarah ballooned from 10 stone to 14 stone.

She vowed to lose weight after her daughter was born but instead continued eating for two and gained even more weight peaking at 15 stone.

‘I was miserable and lethargic but told myself I was happy as I was.  As soon as I woke up the frying pan would go on for a bacon butty and then I would snack on crisps and chocolate until lunch.

Sarah would then usually eat an unhealthy plate of chips for lunch and get a takeaway for dinner.

She never exercised and her BMI passed 30.

‘My boyfriend said my weight didn’t bother him but deep down I was sure it did.

‘It wasn’t just the way I looked, but the way I felt. I had no confidence and didn’t want to do anything.

‘When we split up 2010 I was devastated. I vowed to diet but still couldn’t get the motivation.

But all that changed after the chance meeting in a local shop weeks after the break up.

‘When I saw him walking towards me with a new woman my stomach went. All I could think was ‘she’s slim and I’m fat.’ I went bright red, mumbled a few words and shuffled off. She was half the size of me. It was humiliating.

‘I practically ran out of the shop in tears. I have never felt worse and it was without doubt the turning point for me.’

From that moment Sarah stuck to three healthy meals a day including cereal, salad for lunch and grilled meat and vegetables.

She restricted her evening meal to 500 calories and always ate before 5pm.

‘I was shrinking but I was still like a wobbly jelly, especially my tummy,’ she says.

When she reached a size 14 she decided to start jogging to tone up.

‘I was still embarrassed of the way I looked. Being so short I carried the weight badly. I joined a female only gym to use the running machine.

‘At first I could only do ten seconds without panting but I built up slowly.

‘The more I ran the weight just started to fall off even quicker,’ she says.

And she admits if she ever felt like giving up she only had to think about her ex and his new slimmer woman.

‘A little part of me wanted to lose the weight so I could bump into them again, but the more I lost the less about them it became. I was doing it for me and my daughter. She deserved a happy healthy mum.’

Now she’s gone from a size 16 to a size six, dropping from 15 stone to eight stone.

‘It’s been two years since that embarrassing moment and my body is completely transformed. I’m slimmer and more toned than ever, I dress how I want and I’m so confident, nothing at all like the woman I used to be.

‘I’m pleased it happened and there’s certainly no hard feelings, in fact I have a lot to thank him for. I needed a push. ’

Office worker Sarah’s weight loss and fitness regime has even led her to consider a new career as a fitness instructor.

‘I know how hard it is to lose weight so I would love to be able to help other women. I know how it feels and what they are going through and I can tell them honestly that they can get there. If I can do it so can they.

‘Seeing your ex with a thinner woman helps.’