The Eat Right 4 Your Type diet - which counts Miranda Kerr and Martine McCutcheon among its followers - involves eating and avoiding specific foods based on your blood type.
In an interview with Hello! Cheryl admitted the healthy eating plan helps her feel happier.
'I watch what I eat, not to stay slim but to feel good,' she said.
The X Factor beauty revealed the diet has made a real difference to her energy levels, and came with high recommendation... from her mum!
‘Recently my mother told me about Eat Right 4 Your Type, in which you're told what to eat and what to avoid depending on your blood type,' she said.
'It has made such a difference - not so much to my shape, but to how I feel and my energy levels. Before I was like 'energy schmenergy' and didn't believe it. But now I believe it 100 per cent.'
But Ms C - who jetted in to support the Black Eyed Peas in Cardiff yesterday - also puts her slim figure down to a hectic schedule and energetic dance routine.
‘I have a really hectic schedule but it does have some health benefits - I get to work out without working out,' she said.
'It's literally full-on performances back to back, and all the choreography, training and rehearsals that go into them, that's a real workout.'
But while she's a convert to the blood type diet, Cheryl revealed she's just like the rest of us, and still has a sweet tooth.
‘My only trouble is that I can't do without sugar,' she said. 'Sometimes I feel like I just need a chocolate bar,' she said.
'To be honest you can't put yourself under that much pressure, so I don't deny myself anything.'