Pop star Beyonce Knowles has issued a warning about the maple syrup diet, after previously praising it for helping her lose weight.

The singer lost 6 kilos in 10 days on the diet, which involves drinking a combination of maple syrup, lemon juice, water and cayenne pepper up to 10 times a day.

British health food shops have reported massive rises in the sale of the Madal Bal brand of maple syrup on which the diet is based.

But Beyonce now insists "I'm very happy with my curves" and has warned women to eat sensibly, despite using the diet to lose weight for her role in the movie Dreamgirls.

In an interview on the BBC Breakfast programme on BBC1, the 24-year-old said: "I would never recommend it to anyone unless you are doing a movie and it's necessary, and you have proper help.

"There are ways to lose weight healthily if you want to lose weight, but this was for a film."

In a separate interview with GMTV, Beyonce said she ate doughnuts "and all the other things" to return to her former weight.

"I'm very conscious of being a curvy woman and I'm very happy that I am a curvy woman."

Nutritionists say the syrup does not contain sufficient nutrients and dieters could end up in hospital if they use it for more than few days.