Victor LaValle: 'I was kind of a catch. And I knew this was true. As long as you couldn't see me'

I'd have the charges billed to my telephone, while Margie dialled the same number, but never paid a fee. Much like at nightclubs and bars, it's a lot harder to get ladies into the room, so Margie, and the hundreds of women like her, would call the number and register, then punch through the recorded greetings from thousands of guys waiting to talk with them. One of those men was me.

Each guy's greeting was his name and a little something about himself. Our messages were either lewd or pornographic, nothing else. Using euphemisms about your penis counted as a true gentleman's move. I was no better than the rest. Twenty-one, horny and incapable of getting a real-world date.

The women's greetings tended to differ from the men's; they spoke about amusement parks and dining out and walks on the beach. Ridiculous shit. We all knew why we were here and it wasn't to line up any dates. We were there to talk dirty into our telephones and masturbate in our separate darkened rooms. At least that was true for me and Margie.

We liked each other's voices – each other's imaginations – enough to keep calling back. We'd make appointments for the next "meeting", and then call the line. Scroll through the many recorded messages, listening for the voice we recognised. She was Margie and I was Michael. We spent two years having phone sex and, eventually, speaking to each other off the line, but we never told each other our real names.

Why was I doing this? At 21? I was in college and, in theory, surrounded by eligible women. I should have been besieged by more appropriate partners. My little crew of friends enjoyed no end of sex. Even the losers were doing all right. Not me, though.

I weighed 25 stone, and I didn't stand nine feet tall, so the weight didn't sit well on me. As big as a house? No. I was as big as an estate.

Lumpy and lazy; I aspired to lethargy. In the second year of university, I missed half my classes just because I couldn't pull myself out of bed.

But here's the thing: I was charming. Well read and well spoken. Observant and even kind. In other words, I was kind of a catch. And I knew this was true. As long as you couldn't see me. If you saw me, you'd think I was the sea cow that had swallowed your catch.

Margie lived alone. Her daughter had grown up and moved away. She had retired because she got sick, but she'd saved her money, so she had enough in the bank and the mortgage had been paid off. She never mentioned a husband, and I didn't ask. During the day, Margie ran errands and spent time with her neighbours. At night she entertained her gentleman callers.

One of them was me, Michael, a former school sports star who wanted to become a lawyer some day. I told her I was tall, broad and mixed race. She said she resembled Gina Lollobrigida. Did I know who that was? I said, "Of course" and then looked the actress up.

Both our exaggerations were probably true enough. I did have one black parent and one white parent, and I had played sports at school. As for Margie, I felt sure she was at least a woman who had brown hair. Anyway, when we found each other on the chatline, all suspicions fell away. She was there and I was, too. Our rooms so dark we could imagine each other – and ourselves – exactly as we wanted.

"Hello, Michael."

"Hello, Margie."

"I missed you," she said.

"I'm there with you now," I said.

"Right here in bed?'

"No. I'm outside. Looking in through your window."

She blew out a breath. "My neighbours will see you."

"Then I'd better break in."

"Aren't you afraid I'll hear you?"

"Now I'm standing by your bed."

Margie sighed. "It gets so dark in here at night. I can't see anything."

"But you can feel me getting on the bed."

Quiet. "Yes," she said.

Margie and I were "together" for about two years. After the first year, she gave me her home number and I would call at our appointed times. Neither of us expected the other to stay off the chatlines. If I happened to hear her recorded message there, on one of our off days, calling out the name of a different man, I didn't mind. I was usually listening for a different woman. We'd defeated the madness of monogamy! It required only that we never actually see or touch each other.

Sometimes we talked about visiting each other. But we never would. Both of us knew it. She was a 50-year-old woman with some undefined illness that had forced her to retire 15 years early. Maybe it took some toll on her physically. Maybe she was in a wheelchair, I don't know. But I sure as hell never would let her see me, either.

If she did, how could we ever fantasise about me crouching over her chest again? In real life, I'd suffocate the poor woman between my meaty thighs.

And yet, somehow, I convinced myself that Margie was helping to keep me tethered to the "normal" world of relationships. I knew what we had wasn't complete, but at least we were two human beings sharing some kind of real affection. I still felt this was infinitely better than the alternative: have you ever known men or women who don't get any kind of loving for years? They get weird. The women become either monstrously drab or they costume themselves in ways that make them seem unreal; they externalise their inner fantasies and come to believe that – on some level – they really are elves or princesses or, most disturbing of all, children again. And the men? They're even worse. Men who are denied affection for too long devolve into some kind of rage-filled hominoid. Their anger becomes palpable. You can almost feel the wrath emanating from their pores. Lonely women destroy themselves; lonely men threaten the world.

With that fate in mind, I felt truly grateful for Margie. While I enjoyed phone sex with other women, Margie and I would also have real conversations after the sex was over. She'd want to know what I'd been reading and I'd ask about the home-improvement work she'd been doing. I enjoyed her company, her voice. And she sounded sincere when she told me she'd missed me.

So it came as a shock when she said we'd have to stop talking. Her daughter's husband had lost his job and their home had been repossessed. The two of them, and their three-year-old child, would be moving in with Margie. There was no other way to go. Margie had plenty of space in her home, and she loved the idea of having them close. Her only regret was that she'd have to say goodbye to me. Someone would always be home, and she couldn't risk the embarrassment if one of them overheard us.

So in 1995 my 50-year-old girlfriend, the one I'd never met, broke up with me.

While she and I were "together", I'd thought of myself like an astronaut going on one of those spacewalks outside the space shuttle. Below me I could see Earth, the glorious terrain. The place where true couples dwelled. And while I wasn't there, I could still view it. I knew what it looked like. In time I'd make my way back into the shuttle; I'd hit the thrusters on my spaceship and return to that good soil.

When Margie and I stopped talking, it was as if the craft had blown to bits. I had plenty of oxygen in my suit, but I was no longer tethered to anything. And the shock waves of the blast didn't send me hurtling down to Earth. Instead, they blew me backwards. Deeper into space.

It's funny to have to relate all this first. Because I really want to write about my life after I lost weight. What sex was like once I'd exercised and dieted myself down to under 14 stone. How did I manage the miracle? I bought a refurbished StairMaster and used it four days a week. I started a weight-loss system, and it worked.

I'd found my way back to Earth after drifting through the lifeless void for two years. Victory parades were thrown in my honour (by which I mean my mother was incredibly proud of my change). Here's our man, finally height- and weight-proportionate. Once again, a member of the human race.

But in the time I'd been away – when I'd been inhuman, I guess – I'd journeyed well past innocent phone sex. I'd found another agency that introduced people who really did want to meet in person and make things happen.

I had sex – lots of it – with women who were, essentially, just like me. By which I mean more than 25 stone and crippled by self-loathing. We made our introductions on a phone line, essentially negotiating the details of our affections in advance: I want this and you want that; I won't do any of those things, but I will try these. As a result, I'd show up at some woman's apartment for the first time and we'd be naked in about 10 minutes. Engaging in the kind of sexual fantasies that usually require six months of dating before anyone will even broach the subject. And then they probably still wait another six months before they trust each other enough actually to try it. We covered all that ground in a single night.

And I'll tell you what I learned during those two years: fat people are perverts. By which I mean to say, loneliness perverts you.

I'm not talking about the sex. Or not exclusively, anyway. My first date as a trimmer man scared me more than my first fight. Part of the reason was that I didn't even realise we were on a date.

We met each other at a party in a bar. We shook hands and exchanged a few words. Once or twice we sat in the same frame for those group photos people take as a party wears on. When she sat next to me at a table and smiled before I'd said anything, I had the notion that she might be flirting with me, but the phenomenon had been so rare these last few years that I didn't trust my lying eyes.

Then, a few hours into the party, she came up and asked if I liked her blouse. I was seated and she stood over me. She asked again if I liked her blouse and this time she flipped up the bottom of it and showed me her stomach.

Now, that was flirting. Impossible to ignore. Plus, I didn't want to. This woman was beautiful by any measure. When I saw her skin, I realised how long it had been since I'd seen a belly without stretchmarks. Five years? Ten? I'm including my own in that count.

Before I left, I asked if she would go to dinner with me, and when she said yes, she actually went up on her tiptoes, like a kid.

I took her to a sushi restaurant and sat across from her, but after a few minutes it was clear her face showed none of the same enthusiasm as at the bar. I asked her questions, but she hardly answered. I made jokes, each one worse than the last. Maybe she'd been drunk at the party.

Then, during another moment of silence, I looked away from her and out of the window. There were no couples between us and the restaurant's large front windows. I saw her reflection. She was as lovely as the other night, maybe more so. She wore a sheer sweater and a skirt that flattered her long legs.

And me?

I was still wearing my coat.

Not a jacket. My winter coat. We'd been inside for half an hour and I hadn't taken it off. No wonder she seemed distant, even dismayed; it looked as if I couldn't wait to get away.

And it wasn't just the coat. I had so many layers on. A sweater and a shirt. And a T-shirt under them. It wouldn't have surprised me if I had thermal underwear layered down there as well.

In other words, I was dressed like a fat person. We make the mistake of thinking those layers of clothing are serving to hide us. A kind of protection. Instead, they make us look even bigger. Or, in this case, make me seem like an asshole.

I wanted to explain everything to her. I'm going through a big transition. But I couldn't bring myself to tell her. No matter how I phrased it in my head, it always sounded like a bad pun, a sad joke.

Finally, I slid off my coat, but the gesture must have seemed like pity, because she pulled on hers. We ate the rest of our meal quickly. I took her home on the train but when we reached her station, she said I didn't have to walk her home.

All this changed after I dated the woman with the boyfriend. We became friends first. We worked in the same space, and at lunchtime we sometimes ate together and talked. We were attracted to each other, but did nothing about it for months. She continued to date the aforementioned guy and I was busy trying to live like a normal-sized man; meaning I stayed off the phone lines, ate sensible meals, exercised regularly and told no one that I'd ever been fat. The last seemed particularly important. If enough other people believed it, I hoped that I'd come to believe it, too. If they treated me like a guy who'd never knocked out a dozen Krispy Kreme original glazed doughnuts in one sitting, then I'd forget I ever had. I needed the outside world to convince me because I still couldn't quite believe the transformation had been real.

I was flirting with this woman, but keeping a respectful distance. Getting closer and then pulling away. And she was doing the same. This slow build felt exciting and frustrating.

Each time I saw her again, my feelings seemed even stronger. And that was a shock, too. Feelings. Not to be too self-pitying (or self-aggrandising), but I hadn't really cared about a woman outside my family since Margie and I had hung up our phones in 1995.

I remember the first time she put her arms around me, outside a bar. I held my breath as she clasped her hands around my waist; then she rested her head against my chest.

And finally the two of us are stumbling back to her building. We climb the stairs to her flat. Open the front door, listen for her flatmate, and when it seems we're alone we fall across her living room couch. I'm on my back and she's on top of me. She undoes my jeans and slides them down and lifts her skirt. She climbs back on top of me.

And as much as I'm enjoying myself, as I anticipate the next step with three years' worth of pent-up glee, I'm also not really there.

As soon as my trousers slide down to my knees and my shirt rides up above my belly, I feel myself wince, as if preparing for an explosion. I realise I've been thinking of my clothes as if they were the casing around a live bomb.

Have you ever had out-of-body sex? It's not the same as that tantric business. As soon as my skin touched open air, my mind drifted away. I watched myself and this woman having some wonderfully energetic sex. I even felt proud of the guy down there, because he seemed so free. He was laughing and gripping her hips, but I was floating up by the ceiling, keeping watch. I felt sure that if this woman saw me at the wrong angle, or in the wrong light, her lust would suddenly fold up and be packed away.

Then she reached down and touched my stomach; I'd lost a lot of weight, but the skin there was a little loose, and there were faint stretchmarks along the bottom that looked like dried-out riverbeds. She put her hand on my stomach and I sucked in my belly. I didn't even have that belly any more, but that didn't make the belly any less real to me.

Her hand stayed there on my stomach and I waited to hear her say, "Stop." That, or a groan of disgust.

But instead she did the most perfect thing. For which I remain grateful. She lifted her hand and then brought it back down hard. She smacked me. But not out of revulsion; not to punish me. "Harder," is the only thing she said.

• This is an edited extract from Granta: 110 Sex, out now at £12.99. Annual subscription to Granta (for four issues) is £29.95. To subscribe, go to granta.com/GUARD