HACKENSACK, N.J. - Verdict: He’s the new biggest loser!

A jury yesterday rejected a hefty Florida man’s claim that he was too fat to kill, and convicted him of murdering his former son-in-law.

Edward Ates’ lawyers had said there was no way he could have bounded a flight of stairs, squeezed off the fatal shots and made a quick getaway. Prosecutors said “nonsense,” and included as evidence an unexplained Burger King wrapper found near the body.

Ates looked down and shook his head in court as he was found guilty of murder and weapons counts for killing Paul Duncsak, who was shot six times at his home in Ramsey, about 25 miles northwest of New York.

Ates’ “too fat to kill” defense was a media senation, but made no impression on the jury, which deliberated two days before guaranteeing him a life of prison food.

Some of Duncsak’s family members cried softly after the verdict was read. Ate’s wife, Dottie, sobbed in the gallery as he was handcuffed and led away by court deputies.

“It doesn’t bring him back, but at least he won’t get away with it,” said Duncsak’s sister-in-law, Barbara Duncsak. “It’s satisfying. It was a long time coming.”

Prosecutors credited dogged work by investigators, particularly Det. Sgt. Russ Christiana, who built a circumstantial case around cell phone records and computer forensics. They say Ates drove from Florida to New Jersey, shot Duncsak, 40, a pharmaceutical executive in a bitter custody dispute with Ates’ daughter, then drove 21 hours to his mother’s house in Louisiana.