After being diagnosed with diabetes in May 2011, "I gave up sugar," Baldwin told Access Hollywood at the 18th Annual Screen Actors Guild Awards in L.A. Sunday. "I lost 30 pounds in four months. It's amazing."
Baldwin -- who took home the award for outstanding male actor in a TV comedy series -- is currently dating yoga instructor Hilaria Thomas, though they don't often exercise together.
"I do Pilates and spin, but I don't do as much yoga as I'd like," the 30 Rock star admitted. "When we're shooting and I can't work out, I just have to eat less. So I'm very conscious of that. But sugar was the real killer for me -- that was the problem."
Baldwin isn't the only 30 Rock star to recently slim down: Tina Fey and Jane Krakowski both got their pre-baby bodies back after giving birth in 2011.