May 22, 2020 | 1:20pm

Here’s the skinny on thinness: For some, it’s genetic.

Scientists have identified a skinny gene which predisposes some to staying lean no matter their lifestyle.

In a study published Thursday in the journal Cell, a group of international authors released their findings that individuals with certain variations in a gene known as ALK are physically more resistant to weight gain than most.

“We all know these people: It’s around 1% of the population,” says senior author and University of British Columbia medical genetics professor Josef Penninger in a press release. “They can eat whatever they want and be metabolically healthy. They eat a lot, they don’t do squats all the time, but they just don’t gain weight.”

Penninger and his team analyzed the DNA of more than 47,000 people aged 20 to 44 years old via the Estonian Biobank, and found some thin individuals had a unique variation in their ALK gene. ALK has a reputation as a gene which drives tumor developments, often mutating due to certain cancers, but relatively little is known about its noncancerous role.

Now, though, researchers believe some mutations in ALK might be involved in weight gain and could be targeted to fight obesity.

“If you think about it, it’s realistic that we could shut down ALK and reduce ALK function to see if we did stay skinny,” says Penninger. “ALK inhibitors are used in cancer treatments already. It’s targetable. We could possibly inhibit ALK, and we actually will try to do this in the future.”

Testing the theory in mice and flies, researchers found that the critters and insects were made resistant to diet-induced obesity when their ALK gene was deleted.

The approach is a novel one in the field of weight gain, where far more studies focus on the causes of obesity, not thinness.

“Everybody studies obesity and the genetics of obesity,” says Penninger. “We thought, ‘Let’s just turn it around and start a new research field.’ Let’s study thinness.”