Meghan Trainor is trying to pull a fast one on impressionable adolescent girls, and feminists want her to know she’s not going to get away with it.

Trainor, whose song “All About That Bass” has been No. 1 on the Billboard charts for the past five weeks and has been downloaded almost 3 million times, purports to be an anthem for the pleasantly plump: “I see the magazine, workin’ that Photoshop/we know that s–t ain’t real/ C’mon now make it stop/If you got beauty, beauty, just raise ’em up/ ’Cause every inch of you is perfect/ From the bottom to the top.”

But as authors at websites like Feministing and Jezebel have pointed out, this message of “body positivity” falls flat because she’s not very nice to skinny women in the song, calling them “bitches.”

Oh, and because her measure of attractiveness is . . . whether men find her attractive. “I got that boom boom that all the boys chase/ And all the right junk in all the right places.”

Even after a half-century of feminism, women still tend to judge their bodies by the way others see them. If feminists were simply making the case that you should accept and love your body, no matter how others see you, well who could object?

Indeed, such an attitude would be very similar to what many religious traditions suggest — your body was created in the image of God. If it is beautiful by no other earthly standards, it is beautiful — even sacred — because of that.

But it’s what the feminists don’t object to that’s troubling.

For them the message is that girls need not only to be body-positive but sexually positive. You must be proud not only of ever inch of fat on your hips, but also that you should express your sexuality as proudly as possible.

It’s not right for “All About That Bass” to say it matters what men think of your body; but it’s a good message for a teenage pop song to talk about flaunting your curves.

Anyone who suggests that women might want to think twice about casual sex or dress more modestly is accused of “slut shaming.”

Keeping sexual matters private is considered a form of repression and a sure sign that there is something wrong with you. (Funny how much feminists sound like teenage boys trying to get to third base.)

Indeed, is it any wonder that this is a generation of girls that thinks nothing of sending out naked pictures of themselves? In her cover story for the November issue of the Atlantic, Hanna Rosin interviews police officers in a town in central Virginia about a recent sexting scandal.

“Every time someone they were interviewing mentioned another kid who might have naked pictures on his or her phone, they had to call that kid in for an interview.

“After just a couple of days, the deputies had filled multiple bins with phones and they couldn’t see an end to it.”

And it wasn’t just the girls you might expect. Rosin writes about one who was a “straight-A student who played sports and worked and volunteered.”

High schools may not be filled with girls getting good grades and sending pornographically posed photos of themselves just out of the shower, but the phenomenon is not as rare as we’d like to think.

A friend in Westchester recently told me that her son started receiving unsolicited sexts from girls in his class the summer before his freshman year at a prestigious Catholic high school.

Even if, as Rosin chronicles, some of these girls are receiving multiple requests for these photos from their boyfriends, that is, they’re being pressured into it, sexting seems to display a kind of brashness and level of “comfort” with their sexuality that is inappropriate for 14-year-olds.

Plenty of their classmates — not to mention millions of other Internet users — will be pleased to find all the right junk in all the right places, but that’s not exactly what the mothers I know were aiming for.