‘Seinfeld’ Star Wayne Knight Was ‘on Path’ to an ‘Early Grave’ Before Losing 100 Lbs.

Wayne Knight — who played Seinfeld’s portly postman nemesis Newman on the hit ’90s series — dropped more than 100 pounds after a doctor warned he was eating himself to death! Knight, 69, was smashing the scales at more than 300 pounds when a cardiologist told the 5-foot-7 funnyman he was courting diabetes, heart disease and strokes! “That was the ultimate wake-up call,” a source exclusively tells Closer.

According to Knight, he’s been overeating since childhood, once joking, “I used to get a tan from the light in the refrigerator.” But while shooting a scene for Seinfeld, he realized his health wasn’t what it should be. Knight recalls, “I was being fired at by a farmer having been with the farmer’s daughter, running through a cornfield with my pants down, and at some point in the middle of shooting, I can’t catch my breath.”

But after the physician delivered the serious news, the lardy laugher changed his ways in a heartbeat! “It scared me — literally to life,” admits Knight, who ultimately took the expert’s advice to consult fitness pro Marc Vahanian.

Now, the increasingly svelte star puts in 20-minute workouts at least two times a week at a gym in L.A., uses a gourmet delivery service that keeps his daily caloric intake at around 1,500 — and weighs less than 200 pounds!

Lifespan specialist Dr. Gabe Mirkin tells Closer, “He was on a path to an early grave. He was fortunate to have had very good doctors who gave him very good advice!”