They abuse laxative teas

Britney Spears has never been shy about her love for junk food and engages in all kinds of behaviour to counteract her taste for Taco Bell.

She smokes, drinks coffee and Red Bull, has diet pills in her bag and takes Adderall. She has also been seen hitting all-night drugstores, shopping for laxatives.

And she is certainly not alone.

Today, many actresses are taking laxatives in the form of "dieter's tea", which has a mild laxative effect. Some starlets are drinking up to ten cups a day.

Trainer Gelband says: "The latest trend among models is mixing laxative tea with the master cleanse diet. All they drink is master cleanse and laxative tea."

They chain-smoke

Grey's Anatomy star Katherine Heigl looks to have lost a stone in the last year.

She may be following a healthy eating plan, but she appears to have a secret weapon - she smokes constantly.

A few days ago, the beautiful blonde was spotted having lunch in Los Angeles. She ordered just a salad, but spent the meal chain-smoking.

Nowadays she is rarely photographed without a cigarette in her mouth, and when she isn't smoking, she is clutching a pack.

Marc David, nutritional psychologist and author of The Slow Down Diet says: "It's a choice, really. You are choosing possible lung cancer and death over treating your body with respect, all in an effort to be slim."