Even though they were once part of the same reality TV family, Heidi Montag won't be in attendance at Kristin Cavallari's wedding next year.

The bride-to-be recently revealed that Montag probably won't be invited to her upcoming nuptials, telling Ryan Seacreast, "Heidi changed her number, and I can't get ahold of her."

But Montag, who invited Cavallari to her 2009 wedding to Spencer Pratt, understands her former co-star's reasons for not putting her on the guest list.

"I Twittered her a congratulations [on her wedding] and everything. I really like Kristin, but we aren't super close friends," Montag replied on 'On Air With Ryan Seacrest' Thursday. "Plus it's also too far away, and I don't even know when she's getting married! I didn't get the phone call...so...whatever. I couldn't go anyways. I think her [wedding] is more like hooking up her single friends, and I don't need to be. I'm married."

Montag, who recently revealed she gained 30 pounds while filming her new reality show, 'Famous Foods,' also told Seacrest that the reports she works out 14 hours a day were only slightly exaggerated.