"What did you do yesterday?" Cheryl asks. She arrived at my house half-an-hour later, telling Mum and Tony we planned study time. She even brought the books to prove it, dumping them on my floor and then parking herself on my bed on her front.

"Nothing special," I say. I'm not going to tell her the truth, am I?

"Guess what happened to me? This is so cool!" Cheryl always wiggles her hands around next to her head when she is excited. It's cute.

"I dunno... Robb Stark scaled the walls to your bedroom and invited you to be his chief warrior and join the rebellion against the Iron Throne?"

Me and Cheryl love Game of Thrones.

"Ha! Good one, Savvy—but this is way, way cooler. I've got this new follower on Insta. It's, like, MATT ROGHAM!!!!!"

"OMG!" I shriek, and she joins in. My mum shouts up at us both to keep the noise down, seeing as Tony is trying to sleep after his back shift.

Matt Rogham, if you haven't heard of him and you must live on Mars if you haven't, is an A-MA-ZING actor who started out doing TV and then went to Hollywood a few years ago and has been starring in films ever since. He usually plays the hero and the last film we saw him in was Identity Zero, where he was an undercover cop exposing drug-dealing gangs.

"I can't believe it! Tell me what happened," I say. My friend is now friends with a superstar celebrity. I fast-forward, seeing us doing this and that. In my head, I treat myself to a total body filter, software knocking off inches here, there and everywhere, as camera flashes explode around me.

Cheryl sticks her tongue out so that it touches the tip of her nose. It's her party trick, and her tongue is an even pinky-red colour. Just like those giant jelly strawberry sweets you can buy. I think of everything in sweetie terms.

"Well, y'know that pic of me I put on Instagram the other night? Not the one where I had my tits out, but the other one—that cool selfie? It took me ages to think up words to go with it, but I came up with a girl should be two things: who and what she wants, and—"

"Wait," I jump in. "That's a really cool quote Chezza—did you make that up?"

"Nah," she shakes her head. "I nicked it off someone else. Think it's by some Frenchwoman but she's dead now. Anyway, on with the story! So, I put it up on Instagram and when I checked today TONNES of people had liked it, and then I saw that Matt Rogham was one of them and now he's, like, following me on Instagram."

"Wow," I say. "You can now send him a direct message. Amaze balls."

Cheryl looks shifty. "Can you send him a message, Savvy? You're much better at that kind of thing than me. Pleasy-weasy-weaze?"

"Yeah, whatever." I stick my hand out and she gives me her phone. I sigh, pretending I'm doing her a big favour, but y'know, I'm going to be writing a message straight to a Hollywood super star AND I get to pretend that I'm Cheryl.

Super-cool, super-beautiful, super-slim Cheryl. If I concentrate, I can just about feel my body change to fit her skin.

"Here goes then," I say, "let's Google him to see what's he's been doing."

We find him on some American news sites. He and his girlfriend—American actress Vanda Hoffingham—have just split because they were too busy to see each other, the article says. And he's won an award for best-dressed man under 30.

Actors must get lots of messages like, "oh you're so brilliant, I love your films" kind of thing. I should write something different. Something to make my message, or rather Cheryl's message, stand out.

I begin typing. "Hey Matt, I need advice about clothes and as u've just won an award for style, pls help... :)"

Five minutes later, a reply pings back.

"Hey Cheryl! You'd look good in anything I reckon."

Cheryl stares at me. OMG OMG OMG she starts saying and I join in. She high-fives me and wriggles her fingers like mad.

"Message him back—quickly, we gotta keep this up!"

"C'mon. Try harder. Bet you say that to all the girls!" I type.

"NOOOOOOO!" Cheryl cries as I press 'enter'. "That's too cheeky! He'll hate that."

But two seconds later, another message comes in and I stick my tongue out at Cheryl. "Told you!"

"Awww Cheryl. I meant it. But seriously, what do you want advice on?"

I type something about a party Cheryl's going to (made-up of course) in the city centre—a party, where there'll be bands, artists and lots of celebrities. He sends a message back with a link to a fashion blogger's site, fashionfabulous.com. The clothes on it are way, way too expensive. I mean, £300 for a pair of trousers kind of rubbish. I send him a message saying this and he comes back saying sorry, I should have thought about it...

By the end of it, we've exchanged 30 or more DMs and he signs off with a kiss. Un-bloody-believable. Cheryl high fives me again.

"We need to find someone famous for you," she says, "what about that geeky comedian you like?"

I shake my head. "I'm good. I'll leave the celebrities to you—anyway, I don't want..."

I don't want to put my picture up there; another fat, ugly girl who's too easy to ignore. But I don't say any of that. Cheryl's my best friend. If I tell her what's on my mind, she'll be loyal. Savvy! You're gorgeous, etc. And you know what? She's a shit liar.

"SAVANNAH!"

We look at each other, doing the eye roll thing. Cheryl's only been here an hour or so, and already my mum's interfering. So much for the studying excuse.

"Jan's here. Can you come down?"

I pull a face at Cheryl. "I'm off," she says, "She might have Katie with her."

Jan's my mum's oldest friend and she's got a daughter the same age as me. Katie and I used to be best friends years ago, but when we moved up to middle school, I met Cheryl and Katie seemed—lame. I dropped her, and Katie's never forgiven Cheryl, even though it was my fault.

Cheryl leans over and gives me a hug. "Later girlfriend," she says, and leaves the room, phone in hand and flicking through her apps.

I make my way downstairs to our kitchen, which still smells of the dinner I managed to avoid. Jan and Mum are sitting at the table, and I wave hellos, and then spot someone else. Some lad I guess to be about my age. He's sitting down so I don't know how tall he is—tallness is important to me, because I'm big for a girl—but he's decent looking without being wow. He's got thick, sandy hair (Caramac-colour, sweetie terms again see?), freckles and green eyes, and he winks at me, a gesture I can't help smiling at.

"Hey Savvy, how are you?" Jan always asks, and nowadays I prickle when she does. She saw me the other week, dropping Ben off at school and I was having one of...my post-binge days. Pale, sweaty and not in the mood for small talk with old family friends.

I bet she said something to my mum, and now they're both on check-out Savvy watch.

"I'm fine Jan, thanks."

My mum flips her hand at me—I guess she means me to sit down—so I take the chair next to her and opposite New Boy.

"Savvy, this is my nephew Alexander."

"Sandy," he says, "no-one calls me Alexander." Green eyes meet mine, and I try and fail to read what they say.

Jan's sister, she says, is moving to New York, but she thought it best if Sandy finished off his schooling here before moving so he is going to be staying with her from now on and starts at our school next week.

"... and I wanted to introduce him to a few friendly faces before he starts, you know."

Katie's at the door and she scowls at me before anyone sees her. "Yeah. Savvy's super-duper friendly." She takes the last seat and I battle not to poke my tongue out at her.

"What year are you in?" I ask Sandy.

"Sixth form," he says, "same as you."

"What subjects are you doing?" I'm glad Cheryl has gone. She'd be rolling her eyes by now. "Lame, lame, lame, Savvy." On the other hand, if she was here, Sandy wouldn't have heard my question. He'd be too busy staring at Cheryl, tongue hanging out and all.

"English, Maths, Modern Studies, Spanish and Drama," he grimaces, "think I've bitten off more than I can chew. What about you?"

"Same, but I'm not doing Spanish or Drama—doing art instead."

"You shouldn't have given up the language," Mum nags. We're on shuffle/repeat with this argument, so I stick my fingers in my ears and sing "la la la I'm not listening".

Sandy grins at me, Katie rolls her eyes and Jan shakes her head. Mum reaches over and pretends to swipe at my head. "Less of your cheek, young lady."

"So when are you starting Sandy?"

"This Monday."

"Bummer for you—double English, then double maths, and then the exams next month."

Jan jumps in, "How are you getting on with your exam prep Savvy? You looked terrible when I ran into you the other week. I was really worried about you."

"When was this?" my mum snaps. Uh-oh, worry alert.

"I'm fine – I was just a bit tired," I say and smile as widely as I can. I'm plastered in make-up so I don't look as washed out as I did when Jan saw me the other day.

"So much pressure they put them under these days Josie, don't you think, for these wretched exams..."

I nod along. Let them think that. It's safer.

"Are the teachers any good?" that's from Sandy, which is good 'cause it means we can stop talking about my health, bad or otherwise.

"Maths—shit."

"Savvy! Language!" my mum pipes up, but it's only because Jan and ol' goodie two-shoes Katie are here. The Great British Baker works as a nurse and you should hear what comes out of her mouth at the end of a shift. She turns the air blue in three seconds flat.

"Sorree," I say, and Sandy smirks. "Maths—rubbish, history so-so, Spanish bit weird, drama—everyone fancies her, boys AND girls. English—brilliant."

Katie harrumphs. "What? He is brilliant," I say. "When he teaches, everyone pays attention. And he doesn't seem like a teacher either."

"What's the point in that, then?" she says. "Teachers should be like teachers. Got his pets, hasn't he?"

I shoot her daggers. Katie, aka school swot, school goodie two-shoes, Ms Brainiac, doesn't like our English teacher because he's given me higher marks then her. Yup, little ol' me has had higher marks than super-swot Katie. Once, she suggested we swap papers to see if he would give her essay a good mark if he thought it came from ME. Cheek.

I said no.

Sandy winks at me again when Katie isn't looking.

My mum stands up. "Does anyone want some cheesecake?"

Uh-oh.

She opens the fridge and pulls the tin out, saying "It's this white chocolate cheesecake. I've been making this for so long I can practically do it with my eyes shut and you can all—Oh, that's weird. We ate it the other night and there was loads of it left."

Shit, shit, shit.

"I had a slice when I came back from Cheryl's the other night," I add casually, "but I didn't think there was that much left?"

"That's the trouble with men!" Mum exclaims. "Tony and Ben are always helping themselves to stuff in the fridge. I should get a padlock or something. Oh well—I don't have enough to give anyone a big slice, but would anyone like some?"

"Not for me," I say. Noble, huh?

Jan shakes her head and pats her tummy. "Oh my days, I'd love to Josie, but I'm doing Weight Watchers."

Sandy says yes, as does Katie. I watch them tuck in and try not to stare.

"Want a bit?" Sandy scoops up a bit in his spoon and points it in my direction.

"Nah, you're alright," I say. A spoonful? Yeah, yeah. I'd eat that and then my hand would reach out to grab the rest of the cheesecake on his plate, then I'd move on to Katie's plate and grab hers and then to my mum's and cram the whole lot in my gob.

Some time ago a friend of a friend of a friend (can't say who, obvs) told me this story about Victoria Beckham. Apparently, she's nice to work for, but there is a clause in the employment contract you get with her which says you're not allowed to eat in front of her.

I like to think this is because she'd turn feral if she saw you eating in front of her, grabbing the food out of your hands and shoving it in her mouth, swallowing it before she's even had a chance to chew any of it and then howling at the moon, "GIMME MORE!"

A bit like I imagine for myself now.

Jan and Katie and Sandy and my mum all stare at me, looking at me in disgust as I stuff the lot in. "Wot choo lookin' at?" I would croak at them, and then I would go back to the fridge, I'd finish off the rest of the cheesecake, I'd move to the freezer and heave out the tub of chunky monkey ice-cream, claw it out with my hands, then start on the crisps loads and loads and loads of crisps, and maybe then move onto the bread spread with shed loads of butter yum yum yum...

"Savvy, Savvy!" Mum snaps. "Jan and the kids are off home." I haul my mind from food – CONCENTRATE SAVVY, CONCENTRATE.

Jan throws her arms around me. "Bye, Savvy darling, do take care of yourself." I stiffen my arms so she can't get too close. I don't want her to feel my belly, the belly which feels as it if is taking over my whole body. I can feel her belly though—her big, fat, squishy belly pressing into mine.

No wonder she's joined Weight Watchers.

And then I relax. I've known Jan for years. She's warm and kind and lovely. Suddenly I feel like saying to her, Can you take me home Jan? Can you leave Katie here, and Sandy too, and take me home and shut me up inside your house so I never have to leave and just talk to me, and make me soup and sing me lullabies like you used to do when I was a little girl, please Jan please...

She kisses my forehead. "See you soon love." I nod.

Sandy reaches out a hand (I notice he is tall after all) and ruffles my hair, which would have been okay if me and Cheryl hadn't spent ages following that tutorial on YouTube by Silver Ang about how to make your hair frizz-free.

"See you Monday then."

I nod. As they leave, I noticed Cheryl has PM'ed me. "Got empty house coming up. Gonna have a party. Need to plan tomorrow?"

I groan to myself. Cheryl likes loads of people. I don't like loads of people in one place and I hate parties because we're all expected to drink lots (waste of calories), get off with someone (who? Who? Who?), and generally wreck the joint—and I HATE mess.

But I'm Cheryl's best friend (and I'm good at planning), so party it is. A disloyal thought dances into my brain—Is there is any way I could let her ma know without Cheryl finding out? The thoughts flicker in my head for a few seconds, dancing temptingly. A note, an email, a plea added to it that her ma doesn't reveal her sources etc.?

Oh, there isn't any way.

I go back up to my room and I give the desk a quick wipe with one of those furniture polish cloths before firing up my laptop.

Username – Savvyslim, password – thinnest16.

Savvyslim: Annies, do you ever hate people when they eat? Do you ever think to yourself how weak and stupid they are, scoffing down cheesecake and stuff? I do...

I feel really strong now – I am strong and in control. I am not weak.