Katie Holmes 'cracking under the strain' of life with Tom Cruise

Katie Holmes is cracking under the strain of life with Tom Cruise and is wasting away, it has been claimed.

Katie, 29, recently lunched at her favorite eatery, L.A.'s Joan's on Third looking exhausted, her skin was pale, and she looked feeble and emaciated. "She gave us a weak smile and wave before leaving out the back door," an eyewitness at the restaurant tells Star magazine.

And when the former 'Dawson's Creek' actress was outside, a confused and unsteady Katie leaned against the doorframe before her bodyguard carefully guided her into a waiting SUV.

Katie has been suffering dizzy spells and splitting headaches that make her see black spots and feel faint. Sources say the problem is likely her weight. Although she's already wafer thin, she feels pressure to be even slimmer and is obsessive about dieting.

Although Katie may never admit it, due to Tom Cruise's boundless energy, sources claim he may be the contributing factor to Katie's debilitating headaches. Katie's intense need to live up to the Top Gun star's expectations is really taking its toll, both mentally and physically, say sources.

"Katie doesn't get enough sleep — and hasn't for months now," says one insider. "She's tired and drained much of the day because Tom is so wired, and they stay awake until after midnight. He has boundless energy, and she just can't compete."

And while Tom goes off for days at a time ("His rule is 'You can be with me, but don't ask about it'," says a source), Katie is overseeing the interior design of their lavish $35 million Beverly Hills mansion. "To him, the home is a status symbol," the source tells Star magazine in its latest issue, "so it's on Katie's shoulders to pull off something beyond magnificent, something Tom can brag about.

"She's giving herself headaches thinking about it and making herself sick."