(SLIDE)(BlackDoctor.org) — Whether they’re slimming down to play a perfectionist ballerina or bulking up to a gladiator-esque stature, celebrities often need to change their shape drastically—and on short notice—to ace roles (or meet the expectations of a critical public).
The problem? This type of dieting can be bad for your health. Crash diets can weaken your immune system, leaving you more vulnerable to getting sick and may even hurt your heart. Fast weight gain can be bad news too, particularly for the heart and joints.
Healthy or not, here’s a look at some of the most dramatic transformations.
Mo’Nique
Although the comedian and actress was always vocal about loving her body the way it was, she made the decision to get healthy after being diagnosed with high blood pressure and topping out at 262 pounds.
Mo’Nique, 43, lost around 45 pounds in 2009 by eating healthier. She nixed junk food, red meat, and fried foods, and went from a size 20 to a 14.
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Jennifer Hudson
The Grammy and Oscar winner’s dramatic weight loss was the makeover on everyone’s lips in 2010.
In August 2009, Hudson had to lose her baby weight before shooting her next movie, Winnie, in which she plays Nelson Mandela’s wife (due out this year). She worked out regularly with celeb trainer Harley Pasternak and cut back on calories with help from the Weight Watchers program.
Now the face of Weight Watchers, Hudson, 29, is a slender size 6, down from a 16.
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Al Roker
The Today show’s weather anchor also turned to surgery to get trim. Roker, 56, weighed over 340 pounds in 2002 and was wearing a size 60 suit.
His weight had fluctuated throughout his life, but he had always gained the 30- or 40-pound losses back. In 2002, he underwent gastric bypass surgery at his wife’s suggestion and dropped 140 pounds. He says that he has finally accepted that maintaining a healthy weight will be a lifelong battle even after surgery. Today, he watches his portion sizes and exercises regularly to stay around 200 pounds.
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Star Jones Reynolds
The former co-host of The View at first wouldn’t fess up to having gastric bypass surgery. But having dropped around 160 pounds in just three years, Reynolds, 48, came clean in 2007 that she had done something drastic to lose the weight.
Bariatric surgery isn’t a quick fix, though. Continuing to eat an unhealthy diet after the procedure can cause patients to gain weight right back. However, surgery can be a viable option for the extremely obese.
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Randy Jackson
In 2002, the American Idol judge weighed over 300 pounds. The music legend, 54, struggled to keep his diabetes under control and opted for gastric bypass surgery in 2003.
He lost 100 pounds and has kept it off by eating fewer processed foods, cutting back on fat and sugar, and spending more time walking on his treadmill and playing tennis.
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Oprah Winfrey
When it comes to weight-loss tabloid fodder, Oprah, 57, reigns supreme. Her weight has fluctuated often and drastically, and it’s always been “breaking news.” The yo-yoing is partly due to a thyroid condition, which she said she had leaned on as an excuse to eat whatever she wanted in the past.
In the early 2000s, she trimmed down to a fit 160 and thought she had finally conquered her weight issues. But in 2008, she opened up that she had hit 200 pounds—again. In 2010, she announced on her show that she would never diet again.
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Janet Jackson
A notorious yo-yo dieter, Janet Jackson and her weight have been a near constant topic in the media.
She showed off her incredible body in our December 2010 issue and admitted eating only an apple and a small bag of tortilla chips a day while preparing for her Love Will Never Do music video shoot. Today, Jackson, 44, sticks to a much healthier pescatarian diet and works out regularly with a trainer.