The new Carmelo Anthony wants to be the consummate leader this season. And according to his trainer, that’s what has spurred his startling offseason transformation.

Idan Ravin, Anthony’s personal trainer since he left Syracuse after winning the NCAA title 11 years ago, said his client’s dramatic offseason weight loss stems from his desire to lead the Knicks vocally and by example.

Ravin, like Anthony a product of the Baltimore area, said the hiring of Phil Jackson as Knicks president also has inspired his longtime client. But Ravin also said in an interview with The Post Thursday his offseason work with Anthony is not done and there’s not always assurance weight loss will translate into greater basketball performance.

“Amazing people have been hired over there and he wants to come in as the leader and a top-three player in the world,’’ Ravin told The Post, adding Anthony wants the Knicks to follow his lead. “If [he’s] being meticulous, you should not just follow [his] word, but follow [his] actions.’’

Ravin and Anthony have trained a large amount in Los Angeles, where Anthony has a second home. Anthony’s rigorous training and diet plan began in mid-May and some drills were “tweaked’’ to make them more “challenging,’’ Ravin said.

The trainer, whose other full-time clients are Chris Paul and J.R. Smith, said Anthony’s dedication has been astounding. He said there was no specific diet regimen, though eliminating carbs is a staple.

“It’s consistency,’’ Ravin said. “That’s what it is. No, I’m not going to just juice and cleanse for four days and drop a few pounds. That’s what’s causing the long-term changes.

“Give someone chocolate cake, it’s easy to say no when someone’s around,’’ added Ravin, author of “The Hoops Whisperer,” a new book on his life. “When no one’s around, it’s a gift [to say no].

“Making fundamentally sound choices, eating smart calories, not wasted calories,’’ Ravin said of his strategy with Anthony. “We go out to eat, he’s making good choices.’’

An Instagram photo of a slimming Anthony in Puerto Rico surfaced on his account this week, causing a commotion.

Anthony hosted a charity event there for his foundation and Tim Hardaway Jr., Cleanthony Early, Smith and Knicks general manager Steve Mills attended.

“He’s just tenacious with his training,’’ Ravin said. “He’s working out very hard, ramped it up, being even more meticulous. He’s been super diligent on his diet, extra cardio, rest. A lot of amazing people were hired [by the Knicks] and he’s excited about it. It’s another example of Melo trying to be super prepared.’’

Sources told The Post Wednesday Anthony wants to be speedier in the triangle offense and play with an athleticism similar to his rookie year, when he weighed 230 pounds. Anthony was listed at 240 pounds in the preseason media guide last year, but appeared heavier.

According to Ravin, pounds aren’t the issue, body fat is.

“Weight loss doesn’t always mean better performance,’’ Ravin said. “It’s weight loss along with other things. We’re not talking about this being ‘The Biggest Loser’ contest. He dropped weight, yes. Is he skinny? No. He’s a world-class athlete. He’s very fit.

“[But] it’s not losing weight. It’s decreasing body fat. It’s a piece, just like flexibility and strength. It’s one element of a bigger piece.’’

Ravin has worked at some point with every member of the 2012 U.S. Olympic team, including LeBron James, who also is going through a slimming summer of no carbs.

The trainer said it’s too early to tell whether either James or Anthony will want to play all season this thin.

“[LeBron] might feel the weight loss as helpful now but when he starts playing, not so helpful,’’ Ravin said. “Everyone is always experimenting.’’

And Ravin cautioned it’s too early to celebrate.

“There’s still six more weeks till camp — a lot more work to do. It’s not the time to pat each other on the back. Let’s make sure the goals are met.’’