A “belfie” is a selfie snapped of your butt. It can be difficult to contort yourself into a position to capture such a shot, so luckily, it still counts if someone else takes it for you. 

Many of us weren’t familiar with the term before Jen Selter, but a shade under 4 million Instagram followers later, the New York City resident is doing her damnedest to make sure everyone becomes familiar with it.

At 5-foot-6 and 112 pounds, she is a slight woman with a startlingly sizeable caboose, one who has built a fervent following of women who want to be her and men who want to be with her.

Related: The Science of Why You’re an Ass Man

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She has her detractors, too, of course. They are equally fervent, accusing her of having had ass implants, criticizing the rest of her body, and requesting she perform sexual acts for them.

Reading the multitude of comments—which appear mere seconds after she posts a photo—can be a soul-sucking experience. 

This is what it looks like to build a brand on booty. Maybe. 

Or, maybe this is just it looks like when you have 4 million followers. There are bound to be haters in there somewhere. 

Related: The 25 Most Annoying People on Facebook

Morphing Into an Expert

According to Selter, in 2012, she had a job at the front desk of a gym, and the environment rubbed off on her.

“I would take inspiration from the dedicated people who would come in every day, rain or shine,” Selter told me. “I saw the changes in their bod[ies] and was determined to make changes in mine.”

Related: 9 Jaw-Dropping Weight-Loss Transformations You Have to See to Believe

She began working out, too. Her butt ballooned and muscular definition appeared, so she decided to share her results on Instagram.

About a year into her efforts, her following began to swell rapidly, as well. 

The press got excited about her burgeoning butt, too, with Selter making appearances in The New York Post and New York Magazine, and then Huffington PostElleVanity Fair and People magazine, to name a few.

Yet, even in well-known publications, misprints of her name continue, with “Shelter” to “Setler” cropping up most often, further driving home the point that the emphasis remains squarely on her behind. 

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Typos aside, sponsorship and endorsement deals from clothing and nutrition companies poured in, and Selter quit her day job when she reached 500,000 followers.

She continued to post belfies, and came up with the hashtag “#seltering” to describe a way of posing that best showcases the glutes

Related: Your 5-Step Grooming Guide For Better Instagram Self-Portraits

From there, a curious phenomenon occurred, one made possible on such a large scale only because of social media—the assumption that because Selter looks fit, she is a fitness expert. 

To date, however, Selter doesn’t have a fitness certification to her name, and she doesn’t seem to be in any hurry to garner a more formal education.

“I get fitness tips from personal trainers and friends in the fitness field, but I like doing my own thing,” she says. 

In May 2014, the New York Post gave her a fitness column called “Kicking Butt,” in which she freely dispenses workout motivation, exercise ideas, and often-outdated advice. 

Case in point: In her June 2014 column, Selter writes that it’s “super-important that when you lower down, your knees never go past your shoes” during squats.

This myth seems to be a holdover from ‘80s aerobics instructors and personal trainers.

The reality is that when you adhere to this coaching cue, rather than sharing the load between the body’s joints, undue stress is sent up the bodily chain to the hips and low back, “inappropriately increasing the force” in that area by over 1,000 percent, according to a 2003 study published in the Journal of Strength and Conditioning Research.

Related: How to Do a Bodyweight Squat

Better advice would be to focus on keeping the entire surface of both feet flat on the floor, to initiate the movement with a “hips back” cue, and to make sure the knees track in line with the feet.  

Though it is a common fear, such pronouncements as Selter’s “muscle gets soft if you just let it sit around” (this, too, appeared in her June column) are a biological impossibility, as muscle and fat cells are entirely different entities.

Muscle cells may shrink, or the body may rid itself of them entirely, but they do not turn into fat. (To ensure your body retains that rock-solid muscle, check out THE 21-DAY METASHRED—an At-Home Body-Shredding Program From Men’s Health.) 

Good intentions abound—she isn’t endangering people, by any means, only propagating myths that have been disproven. She is a fitness inspiration to many. She is not (yet) a fitness expert, however.

She has never trained a client, aside from her mother.

“I try to stay on top of the new fitness trends, diets, and research,” Selter told me, mentioning that she’s spent a lot of time poring over forums and social media sites.

Related: The Truth Behind 7 Muscle Myths

(Yet when I followed up—twice—to ask which sites, in particular, she trusted, there was no response.)

Selter has said that it is her life’s mission to motivate and inspire people. Fitness role model is a title she embraces readily, and she is more likely to caption a photo along the lines of “Every sunset is followed by a sunrise and a new start” than with exercise instructions.

And that’s fine—the will to get to the gym initially is where many of us fall down, so whatever sets people in motion is welcome. 

Related: 9 Ways Sports Psychologists Motivate Themselves to Exercise

Still, more often than deep thoughts, captions consist of an emoji or two, or simply the Instagram handle of one of her sponsors. Her photo captions can feel, well, half-assed. She lets the photos of her body do most of the talking.

All this might just be evidence of the tyranny of low expectations. To this point, Selter has not been exalted for her brains, but rather for her beauty. (Actually, her booty.)

This much is clear: She is passionate about the topic of fitness, and it is the type of passion that fuels many great trainers.

The potential is there to inspire great change in not only people’s bodies, but their mindsets. 

I’m not a hater. I’m a hoper. And I hope what Selter reveals next is a growing passion for fitness education, so that she uses her massive momentum for maximum good.

Jen Sinkler, RKC-II, PCC, PM, is a longtime fitness writer, editor, and personal trainer based in Minneapolis. She writes about lifting weights and living well at jensinkler.com.