Beloved wellness trend promises health benefits — but instead it causes weight gain, shocking many

They’re supposed to slim you down — but ice baths might actually be plumping you up.

The frigid wellness fad beloved by celebs and influencers could be backfiring, new research suggests.

Cold plunges — long-touted for easing sore muscles and torching fat — may crank up your appetite and make you gain weight, originally reported on by the Daily Mail.

In a study, volunteers took 30-minute dips in tubs set at 95°F, 79°F and a chilly 61°F before an all-you-can-eat pasta test.

The colder the water, the increased hunger levels — those in the iciest pool scarfed down over 200 extra calories.

Talk about a chilling twist.

Study lead Marie Grigg, a Ph.D. researcher at Coventry University, told the Daily Mail it’s still a mystery why icy dips spike cravings.

She noted that “further research is required to identify if the afterdrop in core temperature is a potential mechanism responsible for compensatory food intake post cold-water immersion.”

With cold plunges trending, experts warn the icy fad could backfire for anyone counting on it to shed pounds — and might force weight-loss pros to rethink their playbook.

New York City trainer Natalya Alexeyenko has a theory.

She said to the outlet, “During cold water immersion, the body kicks into thermoregulation mode — blood vessels constrict, heart rate rises, and metabolism revs to keep your core warm.”

But once you get out, she explained that your body keeps cooling — an “afterdrop” — and sends a strong signal: “We need energy now,” even if you’re not hungry.

The catch? Many of us answer that call with calorie bombs, packing on pounds.

Her advice? Skip the snacks and “refuel smart” with lean proteins, complex carbs, leafy greens — and don’t forget a “warm drink” to tame the urge.

Ice baths and cold plunges may also blunt muscle growth and carry serious risks like hyperventilation, hypothermia, drowning or even cardiac arrest as the body fights icy shock.

As The Post previously reported, cold water squeezes your blood vessels then pops them open, boosting circulation.

But health expert François Haman recently noted to Yahoo Life, “Assuming everybody responds the same way to cold is extremely dangerous.”

He added, “I’ve had some people have a lot of difficulties in the cold; other people had no issues.”

Still, plenty of ice bath fans swear by the benefits. Dutch extreme athlete Wim Hof credits cold therapy and his breathing techniques for boosting body and mind, though research calls the inflammation benefits “promising” but not definitive.

Dr. Craig Van Dien, a rehab specialist, told Forbes there’s only “low-quality evidence” that cold plunges aid depression or recovery — but they can ease muscle soreness.

Bottom line? “Understanding your medical comorbidities and what risk they pose is extremely important before cold plunging,” Van Dien advised.

He also stressed that people with heart or lung issues, diabetes, asthma or chronic conditions should check with a doctor first.

So before you dive in headfirst, remember: That icy plunge or bath might not be the skinny miracle you hoped for — it could be the chill that fills you up instead.