Molly Carmel began stealing and hiding food around age 4.

“If I was going to an amusement park, I was more excited to get a churro than go on rides,” Carmel tells The Post. “I was in an unhealthy relationship with food even at a young age.”

Carmel describes her journey from living as an obese teen to losing more than 170 pounds in her new book, “Breaking Up With Sugar: Divorce the Diets, Drop the Pounds, and Live Your Best Life” (Penguin Random House), out now.

Despite growing up on a low-fat diet of processed SnackWell’s cookies and fat-free pasta sauces, Carmel steadily gained weight. In middle school in the early ’90s, she couldn’t fit into the high-waisted, pleated Z Cavaricci pants that were all the rage. The only store she could shop in catered to plus-size women with limited fashion choices.

“I had been to every weight-loss camp there was,” says Carmel, 42, a Tribeca resident and licensed clinical social worker. “I was going to Weight Watchers meetings at 13. I don’t know exactly what I weighed back then, but it was heavy enough that adults were worried about me.”

By 22, Carmel was at her heaviest — 325 pounds — and so depressed she dropped out of grad school at the University of Michigan before eventually getting a master’s from Columbia in 2002.

“I was so big I couldn’t tie my own shoes,” she says.

Soon after, Carmel had bariatric surgery and lost 100 pounds over 12 months. Unfortunately, over the next three years, she gained half that weight back.

“I felt demoralized and humiliated that such drastic measures couldn’t solve my weight problem,” Carmel says. “Because it wasn’t a weight problem. It was an addiction.”

Then she decided to try something different. Inspired by her younger brother who had cut out sugar with impressive results, Carmel dumped the sweet stuff too.

“I went through a detox of sorts,” Carmel says. “I had sweats and irritability in the first couple of weeks and I wanted to sleep all day — classic withdrawal symptoms.”

But as time went on, she says, it got easier, and soon she was slimming down and had more energy than ever — all “pretty much without exercising,” she says. Carmel has maintained a healthy weight of 150 pounds for almost a decade, just through diet, some pilates, yoga and long walks.

As she found success, she put her master’s degree in social work to good use, helping compulsive overeaters and fellow food addicts. Seven years ago, she started the Midtown-based Beacon Program for food-addiction treatment, where she practices what she preaches.

“I didn’t lose weight until I dealt with my relationship with food, and my relationship with sugar,” she says. “I was using sugar as the solution to my problems — except it was really my problem.”

Carmel’s top tips

Eat, don’t cheat

In Carmel’s world, cheat days do not exist — it’s a concept made up by the diet industry, she says. “Choosing to have a cookie doesn’t mean it has to turn into a ‘cheat day.’ Have one cookie. Stop there.”

Toss out temptation

“Get the food that talks to you out of your house,” Carmel says. Although removing “trigger foods” seems simple, people make this mistake all the time, especially when trying to fill up the cabinets with a spouse or child’s favorite foods. “If there were shortbread cookies in my house right now, I’d eat them all,” she adds.

Buddy up

“Find one or two people who can be your accountability buddies,” Carmel says. “Choose people who can root you on when times get tough and also let you know when you’re rocking it. I have a friend who I text every night and I say, ‘Kitchen’s closed.’ ”