I was sitting in freshman math class when I learned to hate my thighs.

As a child, I thought my body was beautiful. My legs could propel me through a back tuck, where you start standing, flip backwards in the air and land on your feet again. They could somersault off the high dive and still enter the water feet first. They could hike all day long. I descend from Irish washerwomen, ample hips and short, stout legs that can easily birth a baby or survive a famine.

Cut to high school, where I was the only freshman to make the varsity cheerleading squad, thanks to the gymnastic stunts those powerful thighs could execute.

One day, I was taking a note to the football coach when I overheard some football players say my name in the locker room. I heard the comment that I shouldn’t be on the squad, but then the coach invited me into his office and I didn’t hear anything else.

I was devastated. Remember in “Pretty in Pink” when Molly Ringwald’s character decides to go to the prom alone after being mistreated by the cool kids? She tells her father, “I just want them to know they didn’t break me.” I want to tell you how I walked into that room and told all of those stinky, stupid boys that they couldn’t break me, that lions aren’t concerned with the opinions of sheep, especially sheep with terrible acne and no prefrontal cortex.

But I didn’t. Of course I didn’t. Do we ever?

Instead, I slunk back to cheerleading practice, humiliated and teary-eyed. I knew I deserved my spot on that squad, even though I was just a freshman. I had trained hard all summer, had nailed my try out, had earned my place.

I was so naïve; it wasn’t about my capability. The next day in math, I shared the story with my friend Jeff. He bit his lip and avoided my gaze, having information he clearly didn’t want to share. I insisted he fess up.

“Well,” he stammered. “It’s because of, you know, your thighs.”

“What’s wrong with my thighs?” I demanded, my temper flaring.

“Everyone is saying that they’re, you know, um, fat. Cheerleaders are supposed to be hot and those guys don’t think you are skinny enough to cheer.”

At that moment, the tectonic plates of my heart shifted. That comment delineated before and after. I went from loving my body to hating it.

That night, I studied my naked body in the mirror. What a difference 12 hours can make. It was like looking at a stranger, seeing my thighs as if for the first time. Seeing my thighs the ways those stupid boys saw them. I felt ashamed, vulnerable, scared, unworthy and … fat.

I threw away all my shorts and started dieting the next day. My gymnastics coach praised my weight loss, only validating my belief that without the dieting, my body was unacceptable, something to loathe and war against. I saved my money and bought over-the-counter appetite suppressants.

It was 1987, so my Metabolife pills were full of ephedra, a drug that was taken off the market soon after because it caused heart attacks, strokes and deaths. I was sent home from school one day because I was babbling incoherently, weaving through the halls. Thanks to my friend ephedra, I had gone 27 hours without eating.

When my mom picked me up, she recognized the frantic eyes and slurred speech of a speed freak. She went through my room, flushed my stash down the toilet. I had to go to counseling for a bit, and my parents doubled down on watching what I ate (or, as it was, didn’t).

Without the ephedra, my weight stabilized quickly back to its happy place, which was 10 pounds heavier than the place those football players deemed acceptable.

It would take another two decades of food deprivation and punishing exercise to quiet the demons that whispered how fat my thighs are.

Two decades before I realized fat was just a stupid adjective.

An adjective is a word we use to explain or define something. But adjectives are subjective, relative judgments that may or may not bear any resemblance to reality.

To change my life, I would have to change my thinking.

Remember how I said my parents sent me to a counselor? This lovely lady suggested a technique from cognitive behavioral therapy. But at the time, I wanted to be thin more than I wanted to be well. A decade later, I came across the therapy technique while reading my 1987 journal. I tried it and it changed my life for the better.

Want to know how I learned to love my body? Join me back here next week to adopt the practice for yourself.

Erin Smith is the owner of the OM place in Winchester, the author of “Sensible Wellness” and the online host of the OM channel. Follow her on Twitter @erinsmithauthor.