The claims of a “Breatharian” couple who say they’ve survived for nearly a decade on little more than air and sunlight are tough to swallow, according to experts interviewed by The Post.

Akahi Ricardo and Camila Castillo said they’d eaten little more than a piece of fruit or vegetable broth just three times a week since 2008 in an interview with The Sun published last week. Castillo even claimed to have gone without food during her entire first pregnancy, saying she “fully lived on light” and consumed no food.

The story of the couple’s extreme and implausible diet went viral, with numerous outlets picking up the story, including the New York Post. But Tanya Zuckerbrot, a registered dietitian and author of “The F-Factor Diet: Discover the Secret to Permanent Weight Loss,” on Monday threw doubt on the couple’s claims, saying they “belie everything” we know about anatomy and the role that food plays, particularly during pregnancy.

It’s possible to survive up to 21 days without food due to glycogen and fat reserves in our bodies, according to Zuckerbrot. But the maximum time anyone could live without water is 7 days, she says. That drops to even less in extremely hot environments.

“It’s a faulty premise that they could survive off of the sun,” Zuckerbrot told The Post in response to Castillo’s claims of a food-free lifestyle. “If you don’t provide your body with caloric intake, your body will begin to break down.”

Zuckerbrot said the limits of how long people can go without food or water have been determined through observation of hospice patients. And any diet without protein would ultimately lead to conditions like osteoporosis and ultimately death, she said.

“You wouldn’t have muscle mass and you’d waste away,” Zuckerbrot said. “It doesn’t make sense; it defies all common knowledge of what our bodies need to survive. People would starve to death — you can’t live.”

“This couple’s dietary habits are not only unhealthy but quite dangerous,” Lisa Moskovitz, CEO of New York Nutrition Group, told The Post. “While there have not been vigorous studies on starvation in the human body we know that an individual cannot survive very long without food, and especially not without water.”

“These people, if telling the truth, are certainly the exception not the rule when it comes to restrictive eating,” she added.

Asked how such a preposterous claim could be believed, Zuckerbrot said people are always looking for the latest and craziest diet fad, even if it’s not based on science.

“We’re always looking for something that seems holistic, or some new, great diet,” she said. “And there’s something very elitist about this, like ‘I can go without food for so long while you need to eat, you slovenly pig.’ We shouldn’t overeat, but this is really going from one extreme to the other. Both of them are unhealthy and I cannot support either one.”

Zuckerbrot, who advocates a high-protein and high-fiber diet, said calorie restriction has long been a way for severely obese people to lose weight and there’s evidence that modified food intake does result in increased longevity among laboratory rats. Still, a very low-calorie diet — or VLCD — would call for at least 800 calories per day, she said.

“It just makes no sense,” Zuckerbrot said of the couple, who split their time between California and Ecuador, according to The Sun.

Attempts to reach them Monday for comment were unsuccessful.

Castillo, 34, said the married couple of nine years “didn’t eat anything at all” for three years and claimed to have done without food during her first pregnancy in 2011, a claim Zuckerbrot characterized as simply “dangerous.” In general, women who are pregnant need at least 300 additional calories per day, she said.

“As a mother and a registered dietitian, that makes me angry because there’s so much false information out there and this would really put a mother and her unborn child at risk,” she said. “She would be wasting away, along with that fetus.”

Dr. Roshini Raj, a gastroenterologist and associate professor of medicine at NYU Langone Medical Center, was even more blunt about the couple, calling them “delusional” if they really believe in their diet without food.

“It’s obviously something that’s not based in medical fact,” Raj told The Post. “It’s incompatible with life. There is some evidence that caloric restriction may be beneficial to your health, but certainly nothing to this extreme. If they truly believe it themselves, they’re delusional. There’s just no way it would ever be possible.”