It was a fine day at Sugarcube Corner, the Cakes serving their customers and Pinkie Pie busily preparing for one of her many parties. The party pony was always physically fit despite all the sugary treat she devoured over the years. She wasn't going to stay that way for long though.

A knock came to her upper party room door, and she bounced over to answer it. She saw nopony, but found a note and a glass bottle with a pill inside. The note read: "Gain what you lost with this pill! Take it with milk after dinner and the next day you will feel like a new mare, or a mare you were some time ago."

Excited, Pinkie tucked the bottle into her mane and went back to work. Little did she know of what she would gain.

After dinner with the Cakes, Pinkie took a glass of milk upstairs and took out the bottle. She lifted it up and the pill met its fate down the earth pony's throat, follow by the milk. After she finished the glass she went back the finishing her decorating. She was tuckered out when she was done, a bit odd considering she always had energy. She managed to carry herself into her room and fell asleep on her bed.

A while after Pinkie fell asleep, a low rumbling emitted from within, but she didn't stir. As the rumble faded, changes to her body began, a latent effect of the pill. Her body began to get bigger, adipose rapidly began to develop. Pinkie Pie grew and grew throughout the night, developing a second chin and quite a few folds, her small belly she had earlier in the day had turned into a full blown fold ridden gut.

A good five minutes into her slumber, Pinkie Pie began to get fatter...much fatter. Her form expanded a good foot from her body, a large belly began to form and developed into segmented rolls, the mare developed a second and third chin, both them flopped violently as they bulged out from her neck. Her legs bulged with layers of flab, and her thighs and plot weren't left behind, reaching a thickness her hind hooves dwarfed, while her back developed its own segmented rolls.

Soon the party pony was as large as anypony could realistically become. Her cheeks puffy, head resting on three necks, and her belly that touches the ground replaced her old physique. With back rolls on top, and a large plot to boot, Pinkie was, to put it lightly, overweight. To put it truthfully, obese. All this time, Pinkie didn't stir. She was in a candy filled dream, which might have contributed to her blossoming figure which continued to grow well into the night.

With a twitch of an eye, Pinkie Pie woke up from her peaceful slumber. She could hear the sound of the Cakes humming from the kitchen downstairs, along with the miscellaneous noises of her cooking and baking delicious food. The commotion alone was enough to make Pinkie drool, let along the sweet aroma wafting its way upstairs. Pinkie was becoming quite hungry after getting a whiff of what was below her, so she decided to get up.

She yawned and stretched her body in bed, then swung her legs out to the side, and nothing happened. "What in Equestria?" She tried to sit up straight; that was a no go either. Terrified and confused, Pinkie took a look at what was preventing her from getting up. That's when she saw her belly.

It was enormous! With rolls upon rolls, it covered the thighs of her back legs and stuck out a good foot wider than her old frame on each side! With a large amount of effort and quite a few grunts, she managed to get herself out of bed and onto the floor, a loud crash was heard as she fell. She was not going anywhere anytime soon, as her belly was so large it pooled beneath her and blocked her stump-like legs from reaching the ground.

She began to think back to try and figure how she got so large. She then remembered a line from the note: "Gain what you lost with this pill!" She soon realized the pill had made all that party food catch up with her.

Responding quickly to the crash, the Cake came up and gave a knock at the door before coming in. "Don't come in, no pony is allowed to see me like this!"

"Pinkie, it's just us. We just wanna make sure you're ok." The baker ponies pleaded at the door outside Pinkie's bedroom. "We won't hurt you, tell anypony else or make fun of you,"

"O-o-okay..."

When the door was pushed open, the Cakes saw with their own eyes what had happened to Pinkie.

Rolls upon rolls had accumulated on her body, and she had at least four chins underneath the blue mare's pudgy face. Her plot was so wide it would take four chairs at Sugarcube Corner's dining area to support it. Her cutie mark was stretched out so much, it was at least four times the size it was when she first got injured. Extra calories had gone into her belly. Limiting all movement, her torso was immense. Wobbling with every slight movement its host made, she had truly grown into an immobile party pony.

"Pinkie! What happened?" Mrs. Cake asked concerned.

"Remember that pill you left me yesterday?" Pinkie confessed. "All that party food caught up to me because of it."

Just then, she noticed the twins, Pumpkin Cake and Pound Cake, had crawled up onto her back and were bouncing on her like a trampoline. Her figure gave a slight jiggle with each bounce.

"Hey! If it means I can do more for these two, then I shouldn't worry about it!"

The parents decided to leave their kids to Pinkie at that moment, unsure where this was going but relieved that spirits were still high.