Ali Fedotowsky packed on 15 pounds during and after filming The Bachelorette, reports the new issue of Us Weekly, on stands today.

"They'd retape scenes, so all she did was eat and drink," a show insider explains. After the show wrapped, "she binged while unwinding with her family."

PHOTOS: Meet the men vying for Ali's heart

But after she saw her fuller figure on the ABC series' premiere, she was inspired to get back into shape.

"It's been stressful watching herself on camera," the source tells Us of the former Facebook ad-sales rep, 25, who is 5-foot-7. "She's a size 6 and not meant to be super tiny, but she wants to lose weight."

PHOTOS: Check out these hot Bachelorette bikini bods

Her plan includes a high-protein diet full of egg whites, strict calorie counting and daily runs.

"I'm not sure if she's lost anything yet," says the pal. "But she's trying!" 

VIDEO: Try this workout for bikini season

To find out which guy currently vying for Fedotowsky's heart was juggling two girls at home that he promised to marry, why Jillian Harris and Ed Swiderski have hit a rough patch that has put their plans to move to San Francisco on hold and the status of Jake Pavelka and Vienna Girardi's wedding planning, pick up the new issue of Us Weekly, on stands today.