Bollywood actresses are slimming down, as an increasing vogue for showing bare flesh on screen and western ideas about body size and beauty take hold in India's big cities.

Whereas former leading ladies such as Mumtaz and Zeenat Aman once found their curvaceous figures no barrier to success, their modern-day counterparts are as famous for their diet and fitness regimes as their acting and dancing skills.

"There's been a lot of changes in the last decade, whether it's in modelling or in Bollywood," said nutritionist and fitness consultant Venu Hirani, who works in India's entertainment capital, Mumbai.

"Today, the basic requirement for someone wanting to go into either is that they need to be a (U. S.) size zero," she said.

Actress Kareena Kapoor has been the focus of much media attention since appearing in a bikini in the 2008 film Tashan ( Style) -- a significant development in an industry known for its chaste treatment of romantic love. The 29-year-old star slimmed down dramatically for the role and reportedly collapsed on set.

She has since had to deny suggestions that her current weight is unhealthy, instead attributing her smaller size to eating correctly, regular exercise and yoga.

"My size zero is such a hot topic of discussion ... that when Saif (Ali Khan, her actor boyfriend) and I eat out at a restaurant, people don't stare so much at us as ... what is on my plate," she told the Bombay Times newspaper.

"Some even ask the maitre d': 'What is she ordering for dinner?' I love the curiosity element."

Other actresses, including Bipashu Basu and Shilpa Shetty, have launched fitness or yoga videos. Some, such as Priyanka Chopra and Deepika Padukone, often talk about the importance of sports in their health regime.

But while Kapoor and others can turn to their own personal dietitians and fitness trainers for expert guidance, some health professionals fear the phenomenon could contribute to dangerous, unregulated weight loss among fans.

Kapoor herself is also alert to the problem, saying what works for her might not work for everyone.

"What is good enough for me can never be good for you and vice versa," she told the Bombay Times. "All I can say is never starve. Eat right and you will go places both with your shape and your soul."