Melissa McCarthy may be a heart disease candidate if she continues yo-yo dieting.

Recent photos show the 44-year-old “Mike & Molly” star has gone from heavy to slimmer to heavy again – and it could wreak havoc with her health!

Celebrity nutritionist and healthy lifestyle expert Lisa DeFazio, who has not treated Melissa, told The National ENQUIRER: “Yo-yo dieting can damage blood vessels, and the shrinking and growing causes micro tears that create a setup for atherosclerosis and other types of heart disease.”

Melissa, a married mom-of-two – who’s been called “tractor-sized” by a movie reviewer – recently shed 40 pounds from her 255-pound frame.

“But Melissa packed all the pounds back after Thanksgiving,” a source said. “Now she’s binge eating. She can’t resist rich foods and desserts.

“She’s only going to do herself damage in the end if she continues.”

But Melissa admits she’s more “body confident” carrying a heavy frame.

“I’ve never felt I needed to change,” Melissa said. “I’ve always thought, ‘If you want somebody different, pick somebody else.’”