Curled up in bed in her West Village apartment, shivering from cold and exhaustion, Jordan Younger tried to ignore the hunger pangs as she counted down the hours until she could have a glass of green juice.

The then-23-year-old New School student, in the midst of a grueling, monthlong, 800-calories-per-day juice cleanse, was truly suffering: Her lips were blue, her hair was falling out, her skin was blotchy and she hadn’t had her period in six months due to extreme vitamin deficiency.

During that time, she was busy saving face writing her blog the Blonde Vegan, in which she perkily chronicled her strict plant-based diet after building up an impressive 70,000 followers on Instagram.

“The obsession with my diet took up my every waking hour,” Younger, now 25, admits to The Post, speaking as her new memoir, “Breaking Vegan” — about how she controversially turned her back on veganism — is published this week. “It was stopping me from leading a normal life full of social activities and other interests.”

The 5-foot-4 native Californian — who was never skeletal but, at her lightest, saw her weight drop by 25 pounds to 105 pounds — recalls: “I was the textbook example of an ‘orthorexic.’”

Orthorexia is defined by the National Eating Disorders Association as a “righteous fixation on healthy eating.” Unlike other disorders, the focus isn’t on losing pounds, but on only consuming food considered healthy, such as nuts, raw fruits and veggies.

Younger became vegan in her final year of college, not because of ethical reasons to protect animals, but after experiencing undiagnosed abdominal issues.

“In the beginning, it was very cleansing and detoxing, and I had this rush of adrenaline and energy because my stomach problems seemed to be resolved,” she says. Then she found that the natural high she’d been getting was replaced by feelings of fatigue. Her bloating and constipation issues returned, but she continued to follow the strict vegan regimen, religiously posting about it online in the blog she launched in 2013, one month after she graduated.

As the months went on, she was in a Catch-22: Her public profile hinged on her vegan identity, yet her choices were damaging her body. Often she felt so weak, she had to work on her laptop computer from bed. Taking one yoga class would leave her drained for the whole day.

Younger’s turning point came in June 2014, exactly a year after she founded her blog, when she confided in a friend about her lack of menstruation — a condition medically known as amenorrhea — for at least six months.

The pal, who had also suffered from orthorexia, recommended she introduce fish into her diet. Soon afterward, Younger forced herself to eat a small portion of wild salmon — and, within a week, her period was restored.

“It showed me how my body was dying to get back on track,” she says, adding that she instantly started to feel more energetic.

It made me realize how elitist some of the people within that [vegan] world could be. - Jordan Younger, after receiving death threats from vegans

A dietician confirmed that fish and eggs would boost her poor nutrient levels. Refusing to lie to her fans, Younger announced on her blog that same month that she was “transitioning away from veganism.”

That’s when all hell broke loose. Her site crashed within two minutes and 1,000 followers instantly ditched her. Worse, she received anonymous death threats from hard-core vegans claiming she condoned the slaughter of animals and that neither she nor her family had the right to live.

“It was shocking,” recalls Younger, who moved from New York back to Los Angeles around the time of the fallout. “It made me realize how elitist some of the people within that [vegan] world could be.”

Sixteen months after her change of heart, she’s had the last laugh. She’s still supporting herself by blogging, and her musings often log 350,000 page views, matching the amount that she got from the vegan blog. Her Instagram followers have doubled to 121,000.Others, however, were supportive and fully backed her when, two months later, she relaunched her blog as “The Balanced Blonde,” which now features a wider-ranging choice of tips and recipes.

“These days I live without a label, which is much more freeing,” explains Younger, who doesn’t know her current weight but considers herself a “healthy size.” “I still eat a lot of fruit and vegetables and smoothies, but also fish, eggs and sometimes red meat.”

She even scarfed down pizza and pasta on a recent family vacation to Italy.

“I’m no longer the aunt who paces the party table, agonizing over whether to take a slice of her niece’s birthday cake,” she laughs. “Now I’m all about balance.”