CHAZ BONO is facing a heart attack crisis as his weight soars above 270 pounds, worried sources tell The ENQUIRER.

And Chaz’s friends and family – including mom Cher – are terrified that if he doesn’t take drastic measures to lose weight immediately, he will suffer a life-threatening heart attack or stroke.

Chaz, 41, who recently completed gender reassignment surgery from female-to-male, has appeared in public recently looking flushed, sweaty and heavier than ever. Testosterone supplements, which he takes as part of his transition, may be making his health even worse.

"It’s very worrisome," author Mark Bego, who has written two biographies about Cher, told The ENQUIRER. "Chaz has always struggled with his weight, but the problem seems to have gotten worse.

"He’s facing the danger of a serious health setback – like a heart attack or stroke. His mom is extremely worried about him and has put calls out to anyone who might be able to help him lose weight."

Chaz has attempted to slim down in the past but has always failed. In 2005, when he was still a girl, Chastity, he took part in VH1’s Celebrity Fit Club in an effort to shed pounds.

"But he only dropped 24 pounds and wasn’t very happy about it," said a source. "Then he put all the weight back on…and more."

Last year, Chaz, who is 5-foot-5, hired a personal trainer, but repeated the same pattern – moderate loss followed by a quick regain, says the source.

Last summer, Chaz considered the drastic step of having lap-band surgery to curb his appetite, but he backed out, the source told The ENQUIRER.

Part of the problem, the source contends, is that Chaz is a homebody who loves to cook fattening Italian food for his live-in girlfriend of more than four years, 34-year-old Jennifer Elia.

Even worse, medical experts believe the testosterone Chaz has been taking since March 2009 could be seriously compounding the health risks he faces from being grossly overweight.

Dr. Gabe Mirkin, a Florida-based physician and author of The Healthy Heart Miracle, told The ENQUIRER he believes Chaz is at a "very high risk" of suffering a heart attack.

"He is obese, which is a huge risk factor for a cardiovascular event, and he is taking testosterone, a hormone that dramatically lowers your good cholesterol or HDL and increases your chances of cardiovascular disease."

With Chaz’s weight well over 270, according to the source, those close to him are praying he’ll get motivated to get healthy sooner rather than later.

But, added the source: "I don’t think he realizes how serious the situation is."