Kris Jenner, 59, says she 'wants to get back into top shape to compete with Caitlyn Jenner, 65, who has been getting raves for her thin frame'

Kris Jenner was indulging in fast food and cocktails after husband of 23 years Bruce Jenner left her to transition into a woman.

But now that the dust has settled, the 59-year-old momager wants to get back in the gym and show the world that she's just as hot as Caitlyn, 65, who has been flaunting her svelte shape in Herve Leger dresses.

'Kris won't admit it, but seeing Caitlyn look so amazing as a new woman has brought out her competitive side,' a source told the US edition of OK! magazine.

Though the E! producer looked incredible when she took her daughters Kourtney, 36, Kim, 34, Khloe, 30, Kendall, 19, and Kylie, 18, to Star Barts for five days this week to tape a new episode of Keeping Up With The Kardashians, she still wants to be even leaner.

'She's determined to get back into shape,' an insider told the weekly.

The former wife of power attorney Robert Kardashian often works out with celebrity trainer Gunnar Peterson and orders meals from Zen Foods.