"I was ravenous for things like doughnuts and cakes," says the mom of Milo, 2

For Liv Tyler, losing weight after the birth of her son Milo in 2004 was no piece of cake, so to speak.

“I was not one of those women who just dropped pounds instantly when I was breastfeeding,” the Reign Over Me actress, 29, tells Britain’s You magazine. “Actually, I got so homely I was ravenous for things like doughnuts and cakes.”

Tyler – who married Brit rocker Royston Langdon in March 2003 – was determined to be a stay-at-home mom for the first year of Milo’s life. She “hibernated” inside the house, she says, until she had a rude awakening about her weight.

“I can remember walking down the street one day – I was going to the nail salon – when … a photographer took my picture,” she recalls.

“I was wearing a very unflattering shirt that I had worn when I was pregnant and a pair of sweat pants, and when the picture appeared in a magazine they ran a caption asking if I was pregnant again. When I saw it I said, ‘I think the holiday is over.’ ”

Once focused on taking action, “I did a million different things,” she says. “I would be on a strict protein diet and then a raw diet, and then I would do colonics and fasting. And I did Pilates, yoga and working out with my trainer.”

As the face of Givenchy cosmetics, Tyler also admits to discussing moisturizers with an unlikely partner: her craggy-faced Aerosmith frontman father. “My dad, Steven Tyler, and I always talk about creams!” she says.

Still, for all her healthy habits, Tyler has one vice she knows she must conquer. “I’m afraid I smoke sometimes. I did give up for a long time when I had Milo, but on my last film my character smoked and that was bad for me,” she says. “I don’t like it, but I secretly love it. I know it’s terrible.”