“If I offered you a million dollars if you could have an orgasm in the next 60 seconds,” said the psychologist to the woman, “what would you do or fantasize about in order to achieve that orgasm as quickly as possible?”

“I would use my vibrator and probably run the other hand over the thicker parts of my stomach and sides,” replied the woman. “I would likely imagine being fatter than I am, with [someone] telling me how fat I had gotten and how much bigger he was going to make me.”

The foregoing exchange, an email correspondence between the researchers Lesley Terry and Paul Vasey, of the University of Lethbridge, and their subject, a thirty-year-old woman named “Lisa,” comes from a 2011 article on eroticized corpulence in Archives of Sexual Behavior. The authors had stumbled upon this curious case of female “feederism”—a bustling fetish subculture in which one’s most intense sexual pleasure involves eating, gaining weight, or being fed—after inviting members of the website FantasyFeeder.com to participate in their study of fat fetishism. Lisa, who was in fact just as mystified about her lifelong, carnal attraction to obesity as were the investigators, agreed to serve as their main case study.

And lifelong (or nearly so) her desires were. “She experienced erotic thoughts about weight gain and fat from a very early age,” write the investigators:

When she was approximately 7 or 8 years old, she became fascinated with larger people and would pretend her Barbie dolls were gaining weight. When she was 13 years old, she had a dream of a fat woman wearing a crop top (i.e., a t-shirt or blouse with the lower portion cut off, resulting in the exposure of some of the wearer’s abdomen) dancing, and she experienced her first orgasm in her sleep.

Technically, Lisa displayed characteristics of both “feeder” (those who become sexually aroused by feeding their partners and encouraging them to gain weight, sometimes to a state of immobility) and “feedee” (individuals who are erotically aroused by their own weight gain or being forced to eat). What’s especially interesting about her case, however, is the fact that she wasn’t terribly heavy herself. Only a tad overweight, she had a relatively average Body Mass Index (23.1), exercised for about an hour a day 4-5 times per week, and had never been teased for being overweight. She was an intelligent, articulate woman without any history of mental health problems; she was college-educated, happily married, and employed in a management-level position.

Despite an intensely erotic period in her twenties when, sowing her wild oats, she’d gone on a four-month diet of burgers, bacon, pastries, donuts, pizza, cookie dough, and up to 11 milk shakes a day, Lisa had no intention of allowing herself to become morbidly obese or practicing the feederism lifestyle. Although she saw her gluttonous experience of purposeful weight gain as “very sexually arousing,” nearly climaxing upon stepping on the scale (“the arousing part was finding out how much I had gained and, after a certain weight, knowing that I was bigger than ever before”), she stayed in the closet about the nature of her lust.

The reasons for this tension between her desires and her real life were twofold. First, the authors explain, “Lisa had never been in a feedee/feeder relationship because she did not want to deal with the negative health consequences of becoming extremely overweight.” One of the reasons she abandoned her obscenely decadent diet was that she began to feel lethargic, realizing the toll it was taking and the potentially enormous longterm damage that she was inflicting on her body. “Moreover, she wanted to conceal her sexuality from others and she felt that being in [such a] relationship would make concealment more challenging.”

Nevertheless, she was still a very active member of the online feederism community, taking her greatest pleasure in adult websites featuring images of the same female model progressively gaining weight. “Lisa reported that she looked at these types of pictures several times a week while she masturbated,” the authors tell us. She reported that, while she enjoyed sex with her husband, she could only ever achieve a clitoral orgasm by thinking about fat-related things during intercourse. When asked about her steamiest fantasies, Lisa described them as follows:

Gaining weight and being made fun of for gaining weight … being called names like fatty or pig, or someone pointing out how big I am or how much weight I had gained, drawing attention to or describing different body parts, for example, “look how flabby your belly is getting” … I enjoy the sensation of being “stuffed,” but part of that arousal is knowing that it will lead to weight gain later. The power dynamic in force-feeding is appealing to me …. I am aroused by the idea of being under the control of someone who wants me fatter.

This not-so-subtle power dynamic suggests that feederism is a variant of more “traditional” sadomasochism. And although it’s certainly not hard to find a committed dominatrix, sexologists point out that women are far less likely to derive erotic pleasure from being the “S” than they are in being the “M” in the coupling. There’s a small gay male contingency in feederism, Terry and Vasey point out, but this fat fetish couture is overwhelmingly a heterosexual affair: men are the feeders and women, the feedees.

In addition to the sadomasochistic interpretation, the authors speculate about a number of more idiosyncractic, psychoanalytic reasons for Lisa’s unusual sexuality. Could it be related to her mother’s strict control over her diet as a teenager? Freudian fixation in the oral stage of infancy? A psychological defense in which she’s escaped society’s unrealistic expectations and ideals surrounding women and weight?

In the end, we’re left with more questions than answers. As was Lisa, for that matter. “When we asked her why her sexuality was characterized by feederism,” the authors write toward the end of their report, “she said, ‘I am honestly not sure.’”

I discuss paraphilias like this one, and much, much more, in my new book Perv: The Sexual Deviant in All of Us, which will release on October 8, 2013. Follow me @jessebering (#DailyDeviant). For more on all things deviant, and to find out if I'll be visiting a city near you for the Perv book tour, visit www.jessebering.com.