Desperately hoping to head off a health crisis, Nicole Kidman is pleading with overweight son Connor Cruise to get his life under control – but he keeps packing on the pounds.

“Connor is living life in the fast lane,” said a source. “He refuses to work out, eats junk food, parties all night and chain smokes.”

Connor, 19. and a pal were seen leaving the London club Boujis in the wee hours recently after a night of vodka and tequila. Nicole, 47, has been begging Tom Cruise’s 19-year-old son to clean up his act for a year, revealed the source.

“But he doesn’t think he has a problem. He’s been chowing down on greasy burgers and fries, and he smokes more now than ever. He is usually out all night and sleeps all day, leaving no time to exercise.

 “Nicole and Keith offered to buy him a gym membership or hire a personal trainer, but he says he isn’t interested.” In startling contrast, both his parents are huge advocates of healthy living.

“Tom works out six or seven days a week and eats healthy,” said an insider.”He’s never smoked, and while he might enjoy a beer or a glass of wine every now and then, he is not a regular drinker.”

Added the close source: “Nicole is super-healthy. She works out all the time and runs two miles a day. She has an organic garden at her Nashville house and loves nothing more than putting together a salad.

“Nicole and Tom are frustrated. They want him to lose weight, get more sleep and stop smoking before he ends up with a serious health issue.”