Kelly Ripa is losing it! The morning TV talker is losing weight — dropping below 100lbs — and also losing her temper with on-air partner Regis Philbin.

Now her super-skinny frame and out-of-control behavior have execs deeply concerned. They fear the 35-year-old risks cracking up from both the stress of juggling motherhood with Live and her sitcom Hope & Faith and the strain of shedding so many pounds.

“There is definitely something going on with Kelly,” said an insider close to the chat show.

“She used to be so upbeat and sunny, a positive presence on the show, but now she often seems angry and defensive, especially with Regis. The tension on the set between them has gotten so thick lately that you could cut it with a knife!

“Kelly picks at virtually everything he says. Her banter with Regis used to be playful and teasing. Now it often seems nasty and mean-spirited.

“Sometimes she acts like she doesn’t want to be on the show with Regis anymore… and he knows it.”

Another insider told The National Enquirer that Kelly recently launched a vicious attack on Regis. “She’s made it clear to the show bosses she’s had it working alongside Regis,” said the insider. “Saying he’s old and forgetful is one thing, but saying he also turns off younger viewers is hitting below the belt.

“Regis is also smarting from a recent outburst. After he joked about her shooting a commercial for a detergent, saying she didn’t do her own laundry, Kelly shot back, ‘Excuse me, but I really fear you’re suffering from dementia. I do!'”

The source added that the on-air ugliness was also evident when Reege’s friend and fellow talk show host Tony Danza paid a visit.

Said the source: “When Tony came on he talked with Regis about their night out together, and Kelly tried to interject herself into their conversations. She started prattling on about how guys can’t go out and have a good time together without ending up at a strip club. It was a cheap shot and Tony tried not to be drawn into the topic, saying, ‘Come on, I’m a grandpa.’ But Kelly would not stop. Finally, out of frustration, Tony turned his back on her.”

Kelly was an instant hit when she took over from Kathie Lee Gifford — but her popularity has waned.

TV bosses were shocked by viewer responses in recent focus groups arranged to gauge the ABC staple’s popularity. Anti-Kelly comments included claims she was “too skinny,” “fake,” “unrelatable,” and “requires too much attention”.

Said the insider: “Recent research has shown viewers are starting to be turned off by her — just like they became turned off by Kathie Lee.”

The once curvy blonde’s bony appearance is also raising eyebrows. Said the insider: “She comes in to work in the morning, her hair unkempt, looking frazzled. And she keeps losing weight at a rapid clip, looking bonier by the day. Her weight recently dipped down to less than 98lbs.”

For more on Kelly Ripa, pick up this week’s issue of The National Enquirer.