Credit: N/C; News

What a difference two years can make!

According to an insider, Britney Spears' boyfriend, Jason Trawick, has shed an astonishing 50 pounds since he began dating the pop princess in 2009. What's his secret?

"We love to work out," Spears, 29, told Ryan Seacrest last month. "We do stuff together like that. We take walks."

The "Till The World Ends" singer added that Trawick's abs are "definitely ripped."

Looks aside, what does Spears love most about the 39-year-old William Morris Endeavor Entertainment agent?

"He makes me laugh, and we are so comfortable being ourselves," she told Us Weekly two weeks ago. "We like to stay home, order in, watch movies, go to dinner with friends. And we love getting away for the weekend. Some of our favorite spots are Las Vegas, Hawaii or Mexico."