CHARLOTTE, N.C. — Kristaps Porzingis realized he would shrink to nothing if he didn’t take the Knicks’ new dietitian’s advice and inhale a grand-style breakfast.

The rail-thin Knicks 7-foot-3 rookie added 11 pounds from the end of July’s summer league to the start of training camp, but Porzingis started to gradually drop weight as the regular season rolled on and his minutes increased.

After going from 227 to 238 pounds over the summer, Porzingis dropped to 233 by December.

“Now I’m maintaining it,’’ Porzingis told The Post on Saturday. “I lost a little bit at the beginning of the season. It was hard to maintain that, but I’ve been staying at the same weight and I got to maintain this weight for sure. Once the season is over, I’ll try to get up to 245 pounds for next season.’’

Knicks coach Derek Fisher has cited subtle changes in the Knicks training staff in aiding the team’s return to health this season after an injury-marred wreck that was 2014-15. One indicator is Porzingis playing in all 46 games, a surprise that is a credit to a medical staff led by Dr. Lisa Callahan.

In part, Callahan brought in new dietitian Erika Whitman, who advised Porzingis to go full bore at breakfast as his weight declined, and to go to bed earlier.

“I didn’t pay as much attention in the beginning of the season to breakfast,’’ Porzingis said. “I wanted to get to the gym. I’d eat something quick and go to work out. So now I’m getting up one hour, 1½ hours earlier and having a big breakfast so I have energy for the whole day. I’m really focusing on breakfast.’’

Porzingis’ breakfast fare isn’t anything outlandish — just large portions. It helps that his parents have lived with their 20-year-old son most of his rookie season in White Plains, and his mother, Ingrida, is a noted former hoopster and cook. His parents are staying until March.

“A lot of cottage cheese with fruit, then eggs, ham, toast,’’ Porzingis said. “It’s kind of like an American breakfast, but Latvian style. It’s a big meal. I don’t think other people have big breakfasts like me.

“[The Knicks] wanted me to have big breakfasts, but I’m really pushing myself to eat, even when I’m not hungry, so I can have a lot of energy for the day.’’

The Knicks’ research before the draft showed Porzingis was susceptible to anemia — a condition in which the blood doesn’t have enough healthy red blood cells. He contracted anemia as a 16-year-old, when he was in the minor division of the Spanish League, because he wasn’t eating right. Porzingis said he now carries iron pills on all road trips and hasn’t developed a pronounced case since.

“I was so weak and sleepy because of the blood — I wasn’t eating enough,’’ Porzingis said. “Food changed from Lativan food to Spanish food and I couldn’t adjust. I was working out a lot, [had] a growing body and I got anemia. I have a few moments when my iron levels are low, I get sleepy and as soon as that happens, I take my iron pills and I’m fine.’’

Porzingis, who clearly doesn’t want to miss a game, recently has played through a shoulder injury and a bruised foot, but some nights he’s a lot more lively than others. Porzingis revealed he played for a week with jammed index fingers on each hand that swelled up, but have since healed.

Sources say his family is shocked he’s been able to battle through the ailments without missing a single game, keeping his Rookie of the Year candidacy alive.

Porzingis has said he is trying to prove wrong the “durability police’’ — the ones who suggested he would be injury-prone after missing three games in preseason.

“I think [my family] knows I’m able to play though pain,’’ said Porzingis, who is averaging 14 points, 7.8 rebounds and 2.0 blocks while shooting 43 percent. “There’s a lot of stuff going on. That’s why I think they’re surprised. I want to [play all 82 games]. I’m really pushing myself through all the little injuries, little things I have going on. I want to stay strong mentally and play through it and have a complete season. I think physically this is my first year, I’m trying to figure out how to keep stay fresh for every game.’’

The Knicks declined to make Whitman, the dietitian, available for comment.

Even at 233 pounds, Fisher said Porzingis is fine for his rookie year.

“He’s put on the amount of weight that’s good for where he is now,’’ Fisher said. “It’s always hard to hold or gain weight during the season because of the workload and how much energy you expend. It’s proportionate to your overall strength in terms of how much weight he can carry and strength ratio. He’s 20 years old, and as he physically matures, he’ll gain weight naturally. … We’ll try to do what we need to do this summer.’’

Carmelo Anthony, who has missed four games and complained of a sore left knee Saturday, is no guarantee to play Tuesday against the Thunder at the Garden.