Alec Baldwin had an expanding girth over the years and had looked bloated in recent seasons of 30 Rock.

After getting diagnosed as pre-diabetic in May 2011, Baldwin cut sugar out of his diet and embarked on an exercise regime that includes Pilates and spin classes. The result? He dropped 30 pounds in four months.

Kelly Preston, 49, put on excess weight during her recent pregnancy, and feared she would have trouble slimming back down at her age. "When I got pregnant at 48, I didn't know if my body would bounce back," she said.

Thirty-nine pounds later, Preston has dropped below her pre-pregnancy weight, thanks to pal Kirstie Alley's Organic Liaison weight-loss program. (Click ahead to read about Alley's own dramatic weight loss.) "[I] have more energy than I had 20 years ago — and I feel amazing," Preston said. "I'm going to be turning 50 next year — holy sh--! Hey, 50 is the new 30."

Kirstie Alley has never been shy about discussing her body. The Fat Actress star slimmed down as a Jenny Craig spokesperson in 2004 and showed off her bikni body on Oprah in 2006, but had put some of the weight back on before her stint on Dancing with the Stars in 2011.

Thanks to a grueling dance rehearsal schedule on DWTS and a continued focus on weight loss after the show ended, Alley has dropped 100 pounds. "I feel like I'm back in my element," she said. "I honestly didn't even realize what I looked like."

Everyone remembers what funnyman Drew Carey looked like during his sitcom days.

But look at the Price Is Right host now after he dropped 80 pounds. Carey told People he lost the weight by cutting out carbs and going to the gym religiously.

How can we forget Ozzy Osbourne's son, Jack, during the heyday of MTVs The Osbournes?

My, how the reality star has slimmed down as he grew up. Osbourne lost the baby fat with a regime of rock climbing and Thai kickboxing while getting in shape for his extreme sports reality show Adrenaline Junkie, according to The Guardian.

Jack's sister, Kelly Osbourne, also made a name for herself on the The Osbournes.

As we saw during her Dancing with the Stars stint, the starlet has dropped some serious pounds — and has kept them off. Osbourne told Life & Style she's changed the way she eats completely and does Pilates.

Remember what American Idol alum Jennifer Hudson looked like when she came on the scene and won an Oscar for Dreamgirls?

Now as the spokeswoman for Weight Watchers, Hudson has dropped from a size 16 to a size 6, she told People.

See Seinfeld star Jason Alexander before becoming a spokesman for Jenny Craig.

See Seinfeld star Jason Alexander post-Jenny.

John Goodman maintained a husky size well after his Rosanne years.

But clearly not anymore! How did he do it? The actor told People he cut sugar from his diet and works out six days a week.

After her Sabrina, the Teenage Witch days, Melissa Joan Hart became a mother of two boys.

The Dancing with the Stars alum told People she dropped 42 pounds and reclaimed her figure by meeting with a nutritionist and a trainer.

Though Mo'Nique has always embraced her body, the actress wanted to live a healthier lifestyle.

The Oscar-winning star's hard work has paid off. The actress told Jet magazine that she cut out red meat and made a commitment to working out.

Many Lord of the Rings fans best remember director Peter Jackson looking like this.

But fans barely recognized the filmmaker after he dropped a hefty amount of weight following the trilogy's release. Jackson's rep told People that the director skipped craft services and opted for healthier options, like yogurt, muesli or soup.

Ricki Lake was best known for her role as overweight teenager Tracy Turnblad in the original Hairspray before landing her own talk show in the '90s.

But check her out 140 pounds lighter! Lake told Quick and Simple that she signed up for a daily food-delivery service. Her 1,200- to 1,400-calorie-per-day eating plan incorporated a balanced blend of protein, complex carbs and healthy fats.

Popular actress Sara Rue looked like this not too long ago.

The Jenny Craig spokeswoman recently shed more than 50 pounds.

Seth Rogen had no trouble landing movie roles when he looked like this.

But the funnyman hit the gym to prepare for his superhero role in The Green Hornet.

America's sweetheart Valerie Bertinelli struggled with weight issues in the years after One Day at a Time.

But who can forget watching the Hot in Cleveland star's weight-loss progress on her Jenny Craig commercials?