Sarah – Female Muscle Growth Story

By MagnusMagneto

You can buy this story here: Buy Sarah!

This story is also available in the Year 2 Bundle Year 2 Bundle

(This is a preview of the first ~third of my FMG Story, Sarah)

1.)

“Do you even know how many calories that is?” I asked my sister Sarah.  We were in the family kitchen.  Sarah was wearing her usual outfit of a black tank-top and black short-shorts paired with Converse sneakers.  It was a fitting look for a 16 year old girl who recently came to appreciate showing off her body.  While I still hold the mental barriers of being her blood-related brother, even I have to admit that puberty treated her very well.  She was lithe and petite, standing a full head beneath my 5’10” frame.  Her tank-top exposed a few inches of flat midriff, and her thighs were similarly slender.  I would never think of her in a sexual manner, but I can certainly understand her desire to show off her form and the admirers she drew.

Sarah had just finished shoving into her mouth what must have been the 13th cookie I had witnessed her devour.  I was also fairly certain she had eaten more before I arrived.

She looked at me as if I were speaking in another language.  “What?”

I moved over to the container she was eating out of, picked it up, and began reading the nutrition facts.  I knew the calorie count would be bad, but I was startled at just how bad it really was.  “Sarah…” I started, “I saw you eat 13 cookies.  That’s like… over 1400 calories.  I’m sure you ate some more before I got here too.”

She gave an apathetic shrug.  “So what?  I’m having a snack.”

“Sarah, you can’t just… shove over a thousand calories down your throat and call it a snack.”

“Whoa, excuse me bro.” She quipped with a fiery tone.  “But I can do whatever I want.  Are you afraid I’m going to get fat or something?  Why do you care?”

I shrugged.  “Sorry, just trying to be real with you.  A girl your size and activity level probably only needs like 1800 calories a day total.”

“Well, maybe I’ll just be more active then.  I’ll go pump some iron in the basement and turn those cookies into muscles!”

“That…  It doesn’t work that way.” I started, trying to process how I would possibly explain this in simple terms.

“Sure it does.  When you lift weights, it tells your body to turn the food into gains.  Mmm… imagine that bro, imagine your little sister with big guns.” she let out a laugh before flexing her slender arms, which caused next to nothing to happen.

“If you want to get fit, that’s great, but eating cookies and then lifting weights after isn’t the answer.”

Sarah rolled her eyes and let out a sigh.  “Damn you’re dumb bro.  I literally just had health class about that today, and the teacher said that working out makes your body convert food into GAINS!”

“Yes but… that’s simplifying it.  When you work out your body really just -” I droned on for a while about how muscles are damaged and then the body assigns protein to them to be repaired.  All the while Sarah barely listened, as she was clearly mentally elsewhere.

“Riiight.” she cut in eventually.  “So basically, protein equals mega gains.  Got it.”

“No that’s not-”

Before I could finish my sentence, Sarah had opened the fridge and retrieved a jug of whole milk.  She looked down at the label and proudly listed the protein content out loud.  “Eight grams per cup!” she announced, as if that actually meant something to her.

I tried once again to talk some reason into her:  “Well, that helps, but there’s also a ton of other, better sources of protein-”  I stopped myself as she had taken the cap off and began to drink directly from it.

“Hell yeah!” she yelled out in between gulps.  “I can feel my body getting ready for the gain train.  Just gotta finish fueling up, then I’ll go hit dad’s weights!”

I shook my head and considered it a lost cause.  The boys in her class would consider it a shame after she packed on a few pounds from this reckless eating, but I told myself that perhaps that’s what it would take for her to start listening to me.

2.)

About twenty minutes later I heard a loud clanging emanating from the basement.  I presumed it was Sarah, and a few minutes later my suspicions were confirmed.  She was jerking a barbell around like a child with an over-sized toy.

“Sarah!  Careful!” I yelled out.  “You’ll sprain your muscles or injure yourself if you don’t use proper form.”

“Don’t worry about it bro.” Sarah responded coolly.  “I heard that if you confuse your body by mixing it up, you’ll get better results.”

“That’s… that wasn’t referring to THIS!” I pointed to her as she swung the barbell around insolently.

“Jeeze bro.  Take a chill pill.  I’ll mix it up and do it ‘proper’ too.” She relaxed a little and began performing the exercise with better form, although it was still far from perfect.  She was curling the dumbbell with surprising ease.  A small bubble of muscle popped up on each of her arms from becoming pumped up.  “Wow bro!  Check it out.” She said, referring to her arms.  “Getting gains already!”

“Those aren’t gains Sarah.  That’s your muscle becoming pumped up.  It’ll wear off soon.  That said, it is an important-”

“Oh my god shut up.” Sarah barked before dropping the barbell onto the ground with a light crash.  She moved over to a weight bench and slipped underneath a bar loaded up with 100 pounds, readying herself to press it.

“Sarah! Wait!” I exclaimed moving over.  “That’s way too much for a begin-”

“SHUT UP!” she yelled again, and before my very eyes she lifted the bar straight up into the air and pressed it down to her chest.  I was thoroughly amazed that she was capable of performing such a feat.  While 100 pounds on the bench press wasn’t some kind of record, it was still a ton of weight for a girl her size who had never bothered lifting before in her life.  I feared that she would lose control and drop it, severely injuring herself, but instead she continued to crank out repetition after repetition, easily bringing it down to her chest and back up again.

“See.” She sputtered in between reps.  “I told you to just back off!  You have no idea what you’re talking about.”  After the twelfth effort, she finally put the bar back.  I was blown away that she not only managed to perform the exercise with that much weight, but did it twelve times to boot.  She sat up, and there was an undeniable indent in the middle of her chest beginning to form.  Her shoulders and a few other muscles on her upper body looked a bit fuller as well.  Sarah glanced down and noticed this line of definition that I had seen.  “See, instant results!” she declared with a grin.

“Well…”

“No.” Sarah cut in. “Don’t even start.  I don’t want to hear your bullshit about temporary pumps or whatever.  I don’t care.  You clearly have no idea what you’re talking about.  Maybe your body works differently or something.  Just let me do my thing bro.”

I let out a sigh.  It was a lost cause.  She’d eventually have to admit that she was wrong when her pump deflated in a few hours.  “Alright Sarah.” I conceded before seeing myself out.

I heard a combination of feminine grunts and a clanging of weights from the basement for the next few hours.

3.) Later that night, at dinner

Dinner at my house was always fairly traditional.  The whole family (meaning myself, Sarah, and our parents) would meet together almost every night and have a large meal.  Some might say I’m a bit old for this sort of thing, at 19 years of age, but there’s something about these meetings that I generally enjoy.  Tonight however, was something else.

It all started when Sarah first walked in.  Her body was still pumped up from lifting weights.  The small pockets of muscle that had formed remained intact.  I could tell without a word uttered, merely from the way she glared at me, that she viewed this as some kind of victory over me; that she was ‘out of the woods’ and those muscles were here to stay.  Eventually dinner was served: a traditional dish of chicken, rice, and vegetables.  I noticed that Sarah was eating quite ravenously, while also glancing at me, almost out of defiance.

After piling on thirds, I decided to finally speak up.  “I know you worked hard today Sarah, but remember that diet is just as important, if not more so, than exercise is.”

Before Sarah had a chance to give a quip in response, our father stepped in with one of his own: “Your sister’s a growing girl.  She needs all the nutrients she can get.  Go ahead and grab another thigh Sarah.  Such a great girl.  Always full of energy and spunk.  Got a bit of an attitude, but that’s just her being assertive, finding her voice.  Real strong voice too, getting more self assured all the time.  Not that it’s unwarranted, she’s a great looking kid too, puberty treated her right.  A girl like that, why, the world’s her oyster!  We just need to do our best to make sure she gets all the resources she needs.  Helping a girl like her mature into the woman she can become is a family effort.  So, go on Sarah, like I said, grab another one of those chicken legs, don’t listen to your brother, he’s just jealous that life’s on your platter.  Him on the other hand, well, you know, he’s a bit slower on the uptake.  That’s alright though.” Our dad rambled with his usual tone, a mixture of condescension and warmth.

That was one thing that never seemed to change: dad always rambled on and on about the strangest things.

“That’s right dear.” Our mother joined in.  “A girl your age needs to get all of the lean meat she can.  Why, I think it’s a real shame that more families don’t give their daughters more lean meat.  Gosh, I sure hope we haven’t been starving you all this time.”  A worried look met her face as she likely contemplated how much meat was in my sister’s diet growing up.

Sarah flashed a toothy grin at him as she plopped another slab of chicken onto her plate.  She eagerly cut a piece off and placed it into her mouth, staring me in the eyes with a glimmer of mischief, wordlessly telling me ‘I told you so’.  The next few moments were silent as she quickly gobbled down a few more pieces of poultry.  After the thigh was half-way eaten, she spoke again: “You know dad, I’ve started using your weights.  It’s pretty fun, think I might try building up some real muscles!”

“That’s my girl!” Dad exclaimed with a somewhat joyous look in his eye.  “I had been hoping you’d take up a sport.  Exercise is great stuff.  Helps the body which helps the mind.  No use being a brainiac if you’re winded just getting up from your seat!  But to hell with team sports, there’s always concussions and other things going on.  Now weight lifting, that’s a champion’s pastime.  Build yourself up at your own pace.  Only person you need to compete with is yourself.  And gosh, someone like you Sarah, that’s a real rival to have to deal with all the time!  I can’t wait to see you become a true uberman!  Err, uberwoman!”

Our father finally stopped and Sarah was able to make her next announcement:  “In fact, I started earlier today, and I’m already seeing results!” She flexed her arms, causing the small biceps that appeared as a result of her pump to pop up.

“Nice work Sarah!” Our father responded enthusiastically.  “I knew you’d be a natural.  I’m excited to see where your efforts take you.  Why, if you were to channel all that teenage energy into lifting weights, well, gosh, I bet you could be a real pro!  Hell, better than a pro!  Yikes, it probably won’t be long until you’re the strongest person alive with enough elbow grease and determination!”

“Thanks dad.  You know, I think you’re right.  I really must be a natural since I got results already.  Bro over here tried to tell me that this was just a temporary pump or something, but, it’s been hours and the muscles are still there!”

Dad nodded.  “Your brother’s just jealous.  I’ve seen him try to lift weights a few times, but he never stuck with it.  Probably got discouraged.  You on the other hand, why, I bet you can just pack on muscle like it’s nothing!  I knew my muscle genes had to go somewhere!  Why, that explains everything.  He must have gotten none of those genes, and you got ALL of them.  Poor kid.  His little sister’s going to be a real stud while he’ll be stuck as a pencil-neck.  Still, great boy, just needs a kick in the butt.”

They were talking about me as if I weren’t even there.  I could feel anger welling up inside of me, and I knew I had to get a word in before I reached a boiling point.  “That’s absurd on so many levels!” I blurted out.

“Oh really?” Sarah quipped sharply.

“Yeah.  Really!” I shot back.  “That’s not how biology works.  Or genetics.  Or anything!”

“Settle down son.” Dad cut in.

Your father’s right, there’s no need to be so rude.” My mother added.  It was almost as if my parents were a singular entity berating me for trying to inject logic into the discussion.

Dad continued speaking: “There’s no need to be jealous of your sister’s talents.  Why, I before you know it she’ll be stronger than you!  She’s got the drive AND the talent to become a real powerhouse!  You should start being nicer to her sport.  Ride her coattails to the stars if you know what I mean.  She’ll give you a hard time”

“You know it!” my sister chirped. “I’m gonna work out every day.  Maybe even multiple times a day!”

“But that’s… for starters, she’s a female.” I rebutted before quickly adding in a  “No offense, but this is just hard science!  Girls can’t build muscle as effectively as men do!  They have a lower natural limit, they gain less lean mass per month…  And again, it’s literally impossible for new muscles to develop immediately after a workout!”  I must have been red in the face.

Both of my parents shook their heads simultaneously.  “For shame.” My mother muttered.

“Now son.” My dad started again.  “That’s not the way to think about things.  The world is changing you know.  Why, just the other day I read an article on the internet about how women are evolving.  I bet that your sister here is one of these evolved girls.  That would make sense if you think about it.  She comes from top of the line genetics, and she’s just bursting with potential.  Yup, no way around it, she’s part of this evolved strain of super girls.  Pretty fortunate when you think about it.  She’ll just keep getting stronger and better all the time as long as she works hard.  The world is really belongs to evolved girls like her, sport.  You’re just along for the ride.  But hey, you’re directly related to one of these future rulers of the world!  Just play it cool and I’m sure she’ll help you out in the future.”  He shot me a wink.

I too had read this article.  Two articles about this topic actually, and I highly doubted that he read a separate third one.  In fact, I doubted he actually read any articles on this at all!  The first article was a piece about how certain sexual traits were occurring more frequently in females because attractive women had such a vastly higher number of children in comparison to less desirable ones.  As a result, women were developing prettier faces (though I wondered how this would be objectively quantified) alongside larger breasts and buttocks.  An entirely separate article that I also had read mentioned that one scientist predicted that women would evolve to be slightly shorter with thicker builds in the next few generations.  Neither of these had anything to do with what my father was vaguely rambling about.

“Dad, did you actually read the article?” I challenged.

My father let out a hearty laugh.  “Son, I’ve been around the block long enough to know what’s in one of those things from the title alone.  Once you’re street smart like me, you get a real good feel for what those science types mean from their blurbs.  No need to waste your time on the nitty gritty.  Why, I’d be willing to bet that right now Sarah’s evolved body is processing that chicken into even more muscles as we speak.”

“But-” I tried to start, only to be interrupted.

“Whoa, DAD!” Sarah shouted.  “I think you’re right!  I can feel it happening right now!” she flexed her arms and right before everyone’s eyes, the small bicep trembled slightly before it grew slightly larger and more impressive in appearance.

“Go Sarah!”

“YES!” My father yelled. “I knew it!  Sarah really IS one of the evolved women that article predicted.  Why, I wouldn’t even be surprised if she was the FIRST and ONLY evolved girl to surface yet.  Goodness, everyone, just think about what a blessing this is for our family!  Gosh, that’s such a great looking arm for a beginner Sarah.  How about you give it another flex for us all?”

Sarah nodded and obliged: she brought her arm closer towards the center of the table for everyone to get a better look and flexed once again.  This time the small muscle seemed even more impressive, as if it were a quarter of an inch larger and slightly better defined.  She grinned widely and pumped it a few times.

“Now how about you show us your arm son?” Dad requested.

I let out a sigh, but eventually gave in, rolled my sleeves up, and brought my arm to the center of the table before flexing.

“Oooo…” Our mother cooed before reaching over and grabbing onto both of our limbs, giving them a hard squeeze.  “Yours is bigger dear.” She said to me, “but Sarah’s feels a lot harder!  Warmer too!”

“Hear that sport?” my father chimed in. “After one mere workout, your sister’s got higher quality muscle than you.  A couple more, and she’ll be the boss around here!  Hey, that sounds like a great idea actually.  Sarah, once your guns are bigger than your brother’s, you’ll have seniority in the household over him.  That means when it comes time to pick chores and stuff like that, you’ll get first dibs!”

I shuddered as I recalled all of the times I made my sister clean the bathroom with my father’s strange seniority rules.

A wicked grin met my sister’s face.   “Sweet!  I’ll be sure to work out right after I finish refueling with this delish chicken!” she exclaimed before taking another bite.  “Mmm… more protein calories for my muscles!  Isn’t that what you’d say bro?”

I was livid and my head was spinning.  This was all too much to take in.

4.)  The following morning, Saturday

[[In the full story there is a section where Sarah has a morning workout and some more dialog between the characters.  For the sake of this preview, just know that she’s bigger than she was the night before.]]

“So, if I took all of your muscle genes, then if we add them with mine…” Sarah began jabbing her finger into the air, as if she were writing on an invisible chalkboard to keep track of her inane arithmetic.  “That would already mean that I can build muscle twice as fast as a regular person, well, maybe more since muscle genes are probably exponential.”

“Wh-what?  That’s the most ridiculous thing I’ve ever heard, and I was subjected to our father try to rationalize this last night at dinner.”  A chill ran down my spine as I replayed dad’s misguided speech about evolution.

“Good point.” Sarah replied, though I had a feeling she wasn’t actually agreeing with me.  “Dad DID raise a very important variable to this equation.  I’m evolved.  Therefore, my muscle genes must be much more effective than a regular person’s.  The real question here is: are the genes that were supposed to go to you, but went to me instead, also super powered?”

“Sarah.” I started, “Genes aren’t tangible objects that are stolen.  That makes even less sense when you consider that we were born nearly four years apart!  Look, let me try to explain it to you, everyone has the same number of chrom-”  I was interrupted by my sister physically placing her hand on my mouth.  I tried to remove the obstruction blocking my speech, but her grip was surprisingly firm, her tricep and forearm rippled during our struggle.

“Quiet you.  I’m trying to figure this out!” she resumed poking the air with her spare hand while keeping me muffled with the other.  “Anyways, it seems elementary to me that my initial super genes must have converted the genes stolen from you.  That would mean I not only have a double dose of muscle genes that exponentially build off of each other, but they’re ALL evolved.  I must have…  God… I can’t even begin to imagine how much faster I can build muscle than a regular person…  Let alone you bro, since you must have zero muscle genes at all!”

I managed to break free and could finally try to cut some sense into this atmosphere of lunacy.  “Sarah!  That’s not how evolution, nor genetics, nor ANYTHING works!  LISTEN TO ME!”

“Whoa… Bro…”  Sarah hadn’t heard a word I said, she was submerged in a zone of logical fallacies compounding upon one another.  “What if my genes are getting stronger?  By mine I mean yours too… yours that are, uh, you know, in me.”

“WHAT!?”

Sarah nodded.  “I once read a thing online that your lifestyle can change your genetics.  So, since I’m evolved, the stronger I get, the stronger my muscle genes become, which means that I can get even buffer!”

“That’s…” I brought my palm to my face and rubbed for a few moments.  “Nevermind.” I had all but given up.  Nothing was going to convince Sarah of the truth, not so long as her body kept pumping up like this.

“Anyways, how about you be a good bro and get me some fuel for these muscles?”

“Why don’t you just go to the kitchen!?” I responded, visibly agitated.

My sister gave me a playful jab in the shoulder.  She clearly meant no harm, but there was surprising force behind it.  “Come on bro.  You heard dad last night.  I’m going to be the top dog around here.  You should really start doing favors for me now  so I’ll be nicer later on.  Do I need to really bring up all the times you gave me shit when we were younger?”

I was rubbing my temples during her spiel.  “Fine.  What do you want?”

She shrugged, causing a surprisingly defined bunch of traps to snake upward.  “Just get the jug of milk.  The whole thing.”

I considered explaining why this was an idea on multiple levels, but opted to just go with it.  As instructed, I retrieved the milk and brought it back downstairs, handing it to Sarah.  Her eyes lit up like they always do when she’s happy, and she quickly began to drink straight from the container.  It was approximately 3/4ths full when she started.  I presumed that after a few chugs she would stop, but she didn’t.  Sarah continued to pack down ounce after ounce of milk.  I knew that if I personally tried to put down that much milk at once, I’d likely be sick, but apparently Sarah was unphased.  A full minute later, and she had finished the entire thing, tossing the entire container aside, before letting out a refreshed “Ahh”.

I couldn’t help but gulp at this display.  It sounds like a silly thing to find impressive, but Sarah downing that much milk was just… supernatural.

“And now…” she started.  “Time for the gain train!” she entered a state of concentration and slowly began to flex both of her arms.  Right before my very eyes, her body quaked slightly and her muscles grew!  It wasn’t an immense growth spurt, but they certainly became visibly larger.  A cold chill broke down on the back of my neck while the rest of the muscles on my sister’s body similarly expanded slightly to stay in tune with her arms.  After her spurt, she let out a cheerful “Hell yeah!  Awesome!  Now, come over here and let’s compare biceps.” She ordered.

For some reason against my better judgment I complied.  I walked over and brought my arm close to hers before flexing.  Mine was still slightly larger, but in terms of quality she had me beat by a landslide.  Her limb looked far harder, and I was positive that a touch test by anyone would confirm this thought.

“Wow bro.  Just look at our arms.  Mine’s all gnarly and decked out with little details of definition.  Yours is uh…” she let out a laugh.  “Well, it doesn’t look so hot next to mine.”

She was right.  A small split sat at the peak of her bicep’s head, along with a couple of choice veins.  Similarly, a wide separation was present between the top of her bicep and the bottom of her arm, a thick tendon appearing in between.  Mine on the other hand was, well, formless aside from a couple of small lumps upon closer examination.  How was it possible that the difference of quality in our muscles changed this much since dinner last night?  I let out a disgruntled sigh and withdrew my limb, covering it as best I could with my t-shirt.

Sarah spoke again: “Damn bro.  All these gains and I technically started working out less than 24 hours ago!  Plus my genes are going to get stronger and build muscle even better!  I always knew I was awesome, but this is a whole new level.”

“Great, great.” I was past the point of arguing.  I’d let my sister have her little victory here, and after her pump and beginner gains wore down, I could hopefully impart some common sense into her.

“Say,” she started again, “I’ve been thinking about a new idea I want to run by you…”

“Oh god, what now!?” I cried out loud.  I knew that she had no intention of actually running whatever this was by me, she simply wanted to state it to me as a fact.

“I’ve come up with a new theory regarding our genes.  Namely, well, about how you’re so short compared to dad.  The dude’s got a good six inches on you.  Surely all those height genes went somewhere…”  a grin of sheer girlish mischief met her face.

 

((This is just the first third of the story!  Pick it up today to read the rest!)

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