I have long dreamed of becoming a scientist, but now—just weeks after receiving my B.A. in biology from a prestigious university—I’ve decided to leave science behind. I am rejecting a career in science, or rather, science is rejecting me, because much like oil and water, being fat and being a scientist don’t mix.

The problem with being a fat scientist is that, as a scientist, I’m supposed to know better. Science is all about rules, laws, and logic that can be applied to even the most complicated systems. Most scientists subscribe to the notion that losing weight is a simple matter of biochemical thermodynamics: calories in versus calories out. Despite dozens of studies that complicate this reductionist narrative (including Tara Parker-Pope’s notorious report “The Fat Trap”), it’s still the most prevalent belief I’ve faced during my time in the STEM disciplines. In the past four years, I’ve heard everything from subtle implications to blatant statements that any person who’s still fat despite knowing “the facts” is lazy, gluttonous, stupid, and/or lacking self-control.

Lest you think I am being hyperbolic, consider the NYU evolutionary psychologist Geoffrey Miller’s infamous tweet from last spring:

The current scientific climate is cutthroat. Primary investigators must constantly convince potential financers of their work’s superiority over that of rival labs. Students and research assistants are often asked to prove that their credentials are a cut above those of their peers. Living with this pressure turns scientists into vicious competitors, always looking for ways to assert their pre-eminence. This mentality fosters judgment and discrimination, making it all too easy for those in STEM fields to resent and mock the people they see as too weak-willed to stop eating, too apathetic to exercise, too ignorant to pick up a book about nutrition. Fat people, symbolizing the antithesis of everything modern scientists pride themselves on, become easy targets for misplaced aggression.

I’ve experienced discrimination based on my size. A few years ago, I interviewed for a student-researcher position in a prestigious lab. I was intimidated going in—the professor in charge was ruthless in her work and her personal interactions—but her project was exciting, and my résumé was strong, so I gave it a shot. The beginning of the interview seemed normal enough; we discussed my previous experience and what I’d like to do in the lab. But as we began to talk about the lab’s culture, our conversation took an ugly turn.

She told me that her team did a lot of collaborative work in this lab, and she didn’t need someone who was going to “eat more than their fair share of the pizza, if you know what I mean.”

I didn’t know how to respond. I offered a weak smile and said I didn’t really know what she meant.

She looked up abruptly (she had been staring at my stomach) and said, “I think we’re done here.” I sent her three follow-up e-mails, but she never wrote back.

Sometimes the aggression is more direct. One summer I was fortunate enough to obtain a fellowship to work as a full-time research assistant in a cell-biology lab. On a particularly hot day, a new food truck stopped by my building to give away free milkshakes as a publicity stunt. Word spread quickly, and soon all the people in my lab were scrambling to finish their experiments so they could go down. I was working on the computer, so I saved my work and headed out the door.

As I passed by one of my senior lab members, she reached out her arm to stop me. “Are you really going down there?” she asked.

“Of course!” I said. “Have you ever heard of anyone turning down a free milkshake?”

She gave a dramatic sigh and told me I shouldn’t be eating “more than 1,200, maybe 1,400” calories a day. I was shocked by her words but tried not to let it show. Instead I inquired, “How do you know that I’m not?”

Incredulous, she replied that I couldn’t possibly eat that little and still weigh as much as I did. She suggested that I was not measuring my portions correctly, that perhaps I was eating the wrong foods. Here was a woman with whom I worked side by side, a colleague who counted on me to keep her cell cultures alive while she went on vacation, insinuating that I didn’t know how to use a measuring cup! How could she trust me with the future of her research one minute and then imply that I’m too dumb to read a nutritional label or a food pyramid the next?

This bigotry makes it hard for me, as a fat person, to want to stay in STEM. I feel as if the only way for me to be taken seriously as a scientist is to be constantly dieting, proving to my peers that although I may not always have had the “willpower” to restrict my eating, I have it now. I must demonstrate self-control in the presence of food in order for the people around me to believe it will extend to my research.

I can’t stay in a field where it seems that I’m supposed to apologize for my appearance every day. Although there’s a growing movement to promote a more nuanced model of weight loss and metabolism, the mentality that everything comes down to a lack of self-control is still pervasive in the scientific community.

It’s intolerable to be surrounded by people who believe I have a major character flaw based on my waistline—especially when those people should be the ones most willing to accept the complexities of life and the human body. Maybe weight discrimination is just as bad in other fields of study, but at least that discrimination won’t feel like a betrayal from my own kind.

I hope that in the future, scientists will shape up, but until then, I’m leaving science for advocacy. We should not have the quality of our work or our ability to work in a team questioned because of our size. But no attention is paid to how harmful sizeism can be, or to any campaigns to reduce its prevalence in STEM. That’s why I’m going to do my best to raise the kind of awareness that’s sorely needed in these fields. Honestly, science can’t afford to keep losing people like me to its own backward prejudice.

Rachel Fox is a recent graduate of Wesleyan University.