NCIS' Michael Weatherly Drops 35 Pounds in Four Months—See His Before and After Weight Loss Pics!

Actor completes the Nautica Malibu Triathlon

Michael Weatherly has never looked better!

The NCIS star unveiled his slimmer shape at the Nautica Malibu Triathlon Sept. 14. "My friend and I have been swimming in the Pacific every weekend [since early May], and I lost 35 pounds!" the 46-year-old actor told Closer Weekly. Weatherly regularly bikes and runs to stay fit, and the TV star credited his family, friends and colleagues for holding him accountable for his workouts. "I learned that if you say you're meeting someone at 8 a.m. on a Sunday, you have to show up," the former Dark Angel star said.

Regarding the triathlon, the actor tweeted, "The run killed me."

Weatherly has also been documenting his progress via social media.

In May, he shared a picture of himself boxing. "Enjoying the hiatus by replacing the martini with the faux punch," he wrote. In August, he posted a photo of himself on a walk with his 2-year-old daughter. And, 12 days ago, Weatherly tweeted that he was "reading the paper and going to the gym before work!"

Still, Weatherly has actually been a runner for years. "I started running around my 30th birthday," he told Details in 2012. "I wanted to lose weight; I didn't anticipate the serenity. Being in motion, suddenly my body was busy and so my head could work out some issues I had swept under a carpet of wine and cheese. Good therapy, that's a good run. And I like to sweat. It's better than being cold. I like hot countries. I like endorphins. But I don't want to jump out of a plane or take karate or mixed martial arts." Weatherly also revealed that he "loved" running the L.A. marathon, calling it a "communal and wild and a gigantic challenge." He added, "Finishing that marathon means I can do more than I think."

At the time, Weatherly said he aimed to go for a run three times a week.

"Occasionally, great swaths of time pass without a run. And I wonder why I am so anxious," the star said. "Of course, injury, illness, or laziness sometimes intervenes. My legs have become accustomed to the treadmill. And in L.A., running on the street is asking for a distracted texting driver to knock you over."