As my mum, aka the Great British Baker would say, oh fanny flibberty! Instead of the f-word for those of you with nervous dispositions.

It's 11pm. I got back from Cheryl's: we'd had the usual kind of evening. Her ma served us up dinner. I pushed mine about a bit and then mumbled an excuse about having had a big lunch. Afterwards, we went up to Cheryl's room and mucked about on Instagram. And then I came home.

Thankfully, everyone was in bed. I went into the kitchen, shutting the living room door, doing the same with the kitchen door and sound proofing the whole place.

Pulls open the fridge door. Chunk of cheddar dipped in mayonnaise. Thin slice of white chocolate cheesecake. Bigger slice of cheesecake. Bigger slice; oh fanny flibberty, is it now noticeable? Move to the kitchen cupboard and pull out crisps, scoff down half of the opened packet of Doritos. Can blame my little brother (aka the little rat) if anyone notices. Move on to the bread bin. Yum; sourdough fresh loaf from the posh supermarket down the road. Hack off a slice and spread it with butter thick enough you can see your teeth makrs, then a thin layer of Marmite. Yum, yum...

There's the creak of floor boards above me and I freeze. Is someone coming downstairs? I dart about disposing of the evidence. Crumbs gone. Butter knife tidied away. Cheesecake in exactly the same position on the fridge shelf and Doritos hidden.

And now my head whirls and my heart thumps as if it's about to burst out of my chest.

Where are my Annies? I need them.

Savvyslim: "Hey girls, please talk to me! I ate something tonight. I didn't mean to, I've been so good all week, but I was just so... hungry and unhappy, and I had two slices of bread and butter. Please help me because I feel so horrible and so weak-willed..."

THURSDAY

Another night, another write-off. I wake up a FAT FRIGGIN' FREAKIN' mess. I can still taste those rotten Doritos and I'd been good all week too. 

Cheryl and I posted up selfies (hers) last night on her Instagram account because there's this lad she really likes, and she wants to get his attention. He's new at our school and hot; not my type (my cup of tea? No, that's a rubbish description—more like not my kind of cheesecake). She went for the big pout, cleavage on show look and I fiddled around with the filters and the software, so she ended up with even bigger boobs than normal, whiter than white teeth and sparkly eyes.

"Looking good Chezza," I said, but she made me take six more pics until she was absolutely sorted with what I'd done. Hudson filter? No. Mayfair filter? Yuck. Paint filter, perfect. When we finished, we only had to wait a few minutes until Hot New Lad replied, 'get your tits out for the lads...'

"That's not right Chezza," I said. It looked as if she was gonna do it too. "Doesn't your mum check your account?" I pointed out. No need for her to come storming in and for us both to end up banned from Instagram or other such rubbish.

"Stupid bint can't figure it out," she grinned, but she changed her mind about the proper tits out photo. Better treat 'im mean and keep 'im keen, she reckoned, so we thought for a few minutes about some smart Alec reply to send back to Hot New Lad.

I came up with something—I'm better at the words than Cheryl. She stars in the pics though, which is why she's got more than 2,000 followers. We looked through them all once. Cheryl reckoned she maybe knew seven of them.

Just for the record, I'm jealous of Cheryl. Well jel. She's a size eight, and she's got big boobs, long, dark hair, and caramel-coloured, zit-free skin. I'm friends with the gorgeous girl all the boys like. No wonder I came home last night and raided the sodding fridge.

I'm paying for it, though. This is how I feel now... Fat for a start, my tummy is bloated and swollen. I'm lying in my bed, running my hands over it and worrying because I can't feel my ribs and my hip bones. Inside me, I imagine them covered in a disgustingly messy layer of cream cakes and crisps. And I'm bone-dry thirsty—but at the same time I want to burst into tears.

Would that make me even thirstier, I wonder to myself. The water leaching out of my body in tears and further away from my parched throat.

I've also got this hard lump deep inside my belly, lying there and taking up too much room, slowly rotting away and sending all these little bits of food poison through me. UCK.

I blame the Doritos. Rotten Doritos—do they put something on those things, so you can't stop eating them? I'll sneak out later and buy a packet, so Mum doesn't realise I ate them all up.

Sometimes, she notices these things and sometimes she comments.

'Hey what happened to that cake I made? Did someone help themselves to the rest of it? Because I was going to take it to Nana. She's not been eating much lately?'

God, sorry Nana—it's wicked to steal food that is meant for an old lady—but that time I came into the kitchen after a terrible day at school and the cake tin shouted at me. No, it did. Eat me, eat me, EAT MEEEEEEEEEEE...

Mum's a great baker too. She auditioned for the Great British Baker programme last year, but didn't get through because she was using a new oven for the competition and couldn't figure out how to work it. She makes fan-flipping-tastic carrot cake. It's super moist with raisins in it and cream cheese icing that's two inches thick.

I started my cake attack that time by scraping off icing in thin bits. It slid down my throat so fast, I had to keep going. Then only the cake was left, which looked stupid, obvs, so I had to eat that too.

You can only blame your little brother so many times.

Sometimes I use MyFitnessPal to see what I've eaten:

YOUR DAILY CALORIE TOTAL:

6,690 calories

560g carbs

450g fat

Percentage of cals from fat—60%

Percentage of cals from carbs—33.5%

If every day was like today, in six weeks' time you will weigh—AN ENORMOUS HUGE AMOUNT IS THE ANSWER YOU FAT, USELESS BLIP.

The Annies all use MyFitnessPal (they always get that warning about not eating enough) but I don't make my profile public on there. I follow some of them on MyFitnessPal though, for thinspiration.

Apples and diet coke feature a lot in their diaries, along with the odd salad, tins of tuna and single Brazil nuts.

Just thinking about the carrot cake now makes me imagine it in the room with me, and I pull the duvet over my head to escape. Go away, cake!

But it is another day. I push the duvet back down and I get out of bed. Today, I'm supposed to be studying. We're meant to be doing lots of swotting for exams. I worked like a DOG last year, but Cheryl keeps saying there's no point. Her big brother Karl—he's loads older because Cheryl was "a mistake"—left uni three years ago and he had a first in astrophysics or something like that. No job for him yet though 'cos he's got no work experience.

I'm with Cheryl. I can't be bothered working for these exams, but my mum doesn't agree. And nor does my step-dad, Tony. I tell him sometimes that he doesn't have any say in my business seeing as he's not really my dad. But Mum doesn't agree with that either. He has plenty of say in my upbringing, she tells me, seeing as my real dad left the scene 13 years ago and hasn't been heard from since.

Nice of him to give a... fanny flibberty, huh?

"Savannah, are you up?"

I grunt through the door—don't want Mum coming up. "Yeah, got lots of studying to do."

"Have you had breakfast?"

I weigh up my options—to lie or not to lie, that is the question. She'll probably guess.

"No, I'll get something in a bit, wanna get on with my studying."

"I've left out the cereal for you and there's sourdough bread too. Tidy up after yourself please? And you'll need to take your brother to school too."

HALF-brother, I mutter to myself—not out loud though. Mum insists we don't call each other half-brother and half-sister, even if I want to make it clear to everyone he and I only share half our genes.

"Yeah Mum, will do. Have a good day." See, I can do nice too. I'll take the little rat to school. It's just that I won't be eating her cereal and I want no more rotten sourdough bread. Today, I'm not eating ANYTHING. And tomorrow I might not eat anything either, seeing as last night I ate...

Oh, I don't want to think about it. 

Savvyslim: "Hi Annies! Thanks for helping me out with the bread and butter mistake yesterday. I felt so awful and you helped me get through it. You just need to be strong don't you, and you girls help me so much.

"I've been really, really good today to make up for it. You'd be proud of me Annies, I ate hardly anything, and I can see my ribs again, which is great news. Now just need to keep up twork!

"Do you have any tips to keep me being good?"