Khloé Kardashian is in the best shape of her life, but her ex-husband Lamar Odom is worried about her extreme weight loss.

The former NBA star, who recently completed a short stint in rehab, is not a fan of the 32-year-old's new look, and misses her "trademark Kardashian booty."

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“Lamar is worried about Khloé,” an insider told Hollywood Life. “She’s killing herself with all this excess working out, that Lamar barely even recognizes her. He’s been checking her out on social media and she’s working out as if she’s training for the Olympics. Her thighs and legs look like straight bones. And her trademark Kardashian booty went from 100 to 0 real quick!"

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While the couple finalized their divorce this past October, and Khloé has moved on with new boyfriend Tristan Thompson, Lamar's concern is coming from a good place.

"Lam’s not trying to hate," the source continued. "He loved how much concern and support she’s given him through his ordeals and now he wants to return the favor.”

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The KUWTK star, who has dropped over 30 pounds, has been very vocal about the hard work she has been putting in — and even revealed she is not at her goal weight yet!

"I feel great, but I believe that this is a lifestyle," she told E!. "This is a way of life, I'm gonna work out at least three days a week for the rest of my life. It's for health and it's for my sanity, it's for my mental clarity, that's why I enjoy working out."

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She also revealed her "revenge body" was not a way for her to get back at Lamar for his infidelities during their four-year-marriage.

"No, for me it wasn't one person," Khloé said. "For me it's getting revenge just on my life. I feel like the older I'm getting, I feel like I get better and better and I do think I look younger and I feel better than I did five years ago."

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She continued, "People like to assume my revenge was on someone but it's not—it was really even just everyone who called me 'fat' or I'm the 'fat sister' or this or that. But I didn't seek that out intentionally, mine was a byproduct of me really trying to just de-stress myself and as a side effect I was like, 'Wow!' I started losing weight."

We don't think Lamar has anything to worry about! For a look at Khloé complete transformation, click through the gallery below!