Drew Barrymore, once famed for her voluptuous figure, is on an exercise regime to lose weight.

The "Charlie's Angels" beauty says she realised the time had come to thin down when she couldn't fit into her old trousers any more.

However, instead of going on a crash diet and starving herself back to shape, she has taken the sensible option of regular exercise, reports Internet portal Femalefirst.

"The thing that really changed is exercise. I didn't exercise before. But ever since I started, my body has really, really changed. So it turns out that those who say, 'Exercise is good for you' are right. I hate that," Barrymore said.

"I get so shy when I think people are looking. But I guess I was a lot heavier before and didn't notice except when I find my old pants. I saw a test screening of 'Fever Pitch', and I was like, 'Holy shit, my shape is different'."