London, Aug 24 - American singer and television personality Heidi Montag, who recently stripped for Playboy magazine, is planning to go for a second breast implant surgery.

Montag had underwent a breast enhancement in 2007 and now she wants to go under the knife again because she feels her active lifestyle has prompted her breast to shrink, reports contactmusic.com.

'They are not as big as they used to be. I dance a lot, I ride around a lot, I work out a lot. Still I don't know what happened. They are the best things I have ever had, I'm so excited about them every day and I think I want bigger breasts,' she said.