It is not a secret that celebrities face extreme pressures to maintain a perfect body image-- whatever that means. What may be considered normal to the average woman is seen as fat by Hollywood standards of beauty. It is no wonder that many female celebrities go to extreme measures to lose weight. There is a fine line between thin and too thin. Unfortunately, we have seen some of our favorite celebs cross that line in the past-- although, under constant scrutiny, celebrities are bound to overdo it. Here is our list of women who have gone from curvy-hot to stick-thin. These women could stand to learn a thing or two from sultry Kim Kardashian, who knows how to drop weight and stay healthy.

1. Angelina Jolie (above)

In the past few years, Angelina has received a lot of attention for her alarmingly thin frame. Her dramatic weight loss began shortly after the death of her mother in 2007. Grief and stress are causes of weight loss in many women, so it’s no wonder that Angie dropped pounds after receiving the devastating news. It also doesn’t help that the busy mom leads such an active lifestyle-- between her career, Angie's relationship with Brad Pitt, and her ever-growing family, it’s no wonder the Oscar-winner became so skinny.

2. Lindsay Lohan
If anyone knows about being in the public eye, it’s Lindsay Lohan. Not a day goes by that we don’t see LiLo in the tabloids for one thing or another. So, it’s no wonder she has felt so much pressure to be thin. The girl has also admitted to drug and alcohol abuse, which can lead to rapid weight loss. Lindsay has never admitted to an eating disorder-- claiming stress as the reason for her weight loss. Oh, how we miss Mean Girls-era Lindsay!

3. Hilary SwankHilary Swank has never looked better then she did during Million Dollar Baby. Back in 2004, the Oscar-winning actress was toned to perfection-- she hit the gym hard in order to play the role of a tough boxer-- and it showed. Since then, Swank has not only lost her muscles, but she has also gone through a divorce from her husband, Chad Lowe. Could the weight loss have something to do with the stress of her marriage ending? Judging from this picture of her (above) from Vanity Fair’s 2010 Academy Awards after-party, she looks like a shadow of her former self.

4. Jennifer ConnellyFor the past year, the media has been talking about Jennifer’s excessive weight loss. It turns out that Connelly’s thin frame is due to the strain caused by her father’s death. Like Angelina, who has suffered a similar loss, Connelly reacted to stress by inadvertently shedding unnecessary pounds.

5. Kristin CavallariThe Laguna Beach-turned-The Hills star is looking thinner than usual these days. Recently, Cavallari has been appearing on red carpets with a new, smaller frame. Although she has always maintained a fit body, we like Kristin better with a few more curves. Could it be that the drama of The Hills is finally getting to her? Whatever the reason is, we hope Kristin gets her more voluptuous body back soon.

6. Kate Bosworth

In her Blue Crush days, Bosworth’s body was definitely something to be envied. Things are a little different now-- Bosworth has been looking more scary than skinny in the past couple of years. Media has speculated that Kate’s bony frame must be the result of some type of eating disorder, but the actress has denied the rumors. All we know is that the hot surfer girl look worked for her.

7. Ashlee SimpsonAfter her highly publicized nose job in 2006, Simpson underwent a full body makeover. She changed everything-- from her hair color to her weight. Ashlee has always been the smaller of the Simpson sisters, so it was quite the shocker when she dropped even more weight. Luckily, with the help of a pregnancy, Simpson has been able to put back on some much-needed pounds.

8. Christina RicciChristina Ricci is definitely no stranger to weight struggles. The actress has admitted to battling anorexia in her teens, but recently, her weight seems dangerously low. This is not the first time Ricci has received attention for her weight-- since the beginning of her career, she has become a notorious yo-yo dieter.

9. Nicky HiltonThe younger Hilton sister is usually pretty good about staying out of the public eye, but her new bony frame has had the media talking. Her already-thin body appears to be wasting away, with no signs of body fat or muscle. We’re hoping Nicky is just going through a phase, because we like her much better with a little meat on her bones.

10. Renée ZellwegerThe Bridget Jones' Diary actress is a veritable expert in gaining and losing weight-- she has been doing it for years. It seems like every time she has to gain weight for a role, she ends up losing double the amount when production ends. She has yet to find a happy medium. If we had to choose, we’d go with curvy over skinny Renée any day.

11. Nikki CoxRemember the days when Nikki Cox used to be considered a sex symbol? In the 90s Nikki played the hot it-girl on Unhappily Ever After. Sadly, these days, her scarily skinny body is becoming increasingly hard to look at. Her once ample chest is now nothing but skin and bones.

12. Keira KnightleyFor as long as we can remember, it seems that The Pirates of the Caribbean star has been fighting off weight loss rumors. Actually, the last time that we can recall seeing a curvier Knightley was in her film, Bend it Like Beckham. The actress, who played the role of a soccer star, had a noticeably more athletic body back then. Knightley has been very vocal about the fact that both her grandmother and great-grandmother suffered from anorexia, but maintains that she has not followed in their footsteps.

13. Mary-Kate Olsen Mary-Kate Olsen is one of the few celebrities who have actually admitted to suffering from an eating disorder. At 18, after months of speculation, MK checked herself into rehab to seek treatment for her illness. The diminutive actress raised eyebrows when photos surfaced of her rail-thin frame, complete with a visible spine. Since her stint in rehab, Mary-Kate has put on some much-needed weight, and is looking better than ever.

14. Hilary Duff The former Disney star, who was once known for her healthy weight, is no longer the average-sized girl we knew and loved. It seems that the pressures of Hollywood finally caught up with her. Duff received endless criticism for her drastic weight loss a few years ago-- with many detractors claiming she was a bad influence on young girls’ body images. Since then, Duff seems to have found a healthy medium between stick-thin and curvy-hot.

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