She's sworn off foods such as fried chicken and burgers, and has banned animal fats, sugar, caffeine, gluten and alcohol.

'This 21-day cleanse gives me a chance to think about eating differently and see what my attachments are to certain kinds of foods and what I'm willing to do to change,' Oprah writes in her blog. 'I don't know if I'll feel better or worse, but I'm willing to see if my body at least feels differently.

'Now the flab's falling off, and Oprah, 54, says she feels 'healthier and full of vitality'.

'I was focused on what I had to give up - sugar, gluten, alcohol, meat, chicken, fish, eggs and cheese. "What's left?" I thought. Apparently a lot. I can honestly say every meal's
a surprise and a delight.'

Oprah's detox was inspired by her spiritual guru Eckhart Tolle and Kathy Freston's book Quantum Wellness, which has challenged Oprah's thinking.

'Kathy talks about an overweight friend who didn't conquer the weight issue until she became a "conscious eater" - it struck a nerve,' Oprah says. 'I'd recently come to the conclusion that bringing a higher level of awareness to my eating was the solution I'd been avoiding. My idea of a conscious eater wasn't allowing yourself to eat emotionally, as I have struggled with for years. I thought it meant being conscious of every bite and not scoffing down a meal.

'But Kathy speaks of "spiritual integrity". How can you say you're trying to spiritually evolve without a thought about what happens to the animals whose lives are sacrificed for gluttony?'
But those close to the star aren't convinced.

'Oprah hopes to lose 15 pounds [7kg], which will motivate her
to lose another 25 [11kg] by the end of the year,' a source says. 'But she's been yo-yo dieting for years - this is just the latest fad.'

Read the first 7 days of Oprah's detox diet

By Drew MacKenzie