"What if we both gained weight?" you suggested, "That way you wouldn't be the only one overweight, and we could prove to mom that we can still get good grades and be helpful."
Tabitha bit her lip, thinking it over. It was kind of out of the blue, but it couldn't hurt to suggest it. Maybe then you wouldn't feel quite so self conscious about it if you knew that you and Tabitha were in it together.
"Okay." Tabitha said, "I guess I'm in. I'm sure I'd just end up putting on weight anyway."
You smiled back at your sister, glad that you'd have help with your goal.
"That's the spirit!" You said, "Now let's get to work!"
"I'll just need some snacks first." Tabitha said, digging through an empty box in search of something. You looked her over, feeling a little glad her usual tight pajamas and shirt were slightly stretched tight over her belly. You couldn't deny that you were curious what it would be like to be fat like her.
"My stash!" Tabitha exclaimed, pulling something out of the box, "I've got some candy stashed in here!"
You smiled as she pulled out a large bag of skittles and other sugary treats. You looked over at her, her big belly turning to face you as she ripped the bag open and stuffed some into her mouth. You joined her in devouring the treats willing yourself to get fatter. You wanted a body like your sister's. You wanted to be fat enough, that people didn't question it. That would mean never being ashamed of yourself though.
You spent the next several hours eating and playing. You loved spending time with your sister, and now that you knew she was going to join you on her journey, you were feeling a bit more confident.
Over the next couple of weeks, you found yourself trying to match what Tabitha ate, and though it was hard at first, it definitely was starting to get easier. At first you didn't really notice any changes in your body, but after about the third week, you noticed that your pants were starting to dig into your waist uncomfortably. Thinking you were just growing, you tried to ignore it, focusing only on getting fatter.
However, soon you started noticing other small differences. For one, your bra was starting to fit differently, and another was that your face was starting to look a little puffy. You found yourself in looking in the mirror a lot more often, trying to gauge if you were really getting fatter, or just growing.
After about a month of trying to gain weight, you finally knew it was paying off. You noticed that your belly was starting to look a little bit softer, and your belly button a bit deeper. With a couple of steps forward, you were finally starting to get there. You smiled as you poked at your belly.
"It's about time." Tabitha said, giving you a playful slap on your soft stomach, "It's like I set the bar too high."
"Just you wait." You shot back, "I'm getting fatter than you."
"Whatever." Tabitha said, smirking, "You'll never be fatter than me."
You gulped, suddenly feeling a surge of determination. You had to be fatter, if you had anything to say about it.
Over the next month, you not only gained weight, you enjoyed it. Part of you was surprised that you didn't try to stop gaining weight, but it just felt so good to finally just let yourself go. You were finally living life like how you wanted to for once. Though you felt like you were the odd one out now that you and your sister were gaining weight together. You were also worried about what your mother would say as your gain became more and more noticeable.
However, you were surprised by how quickly your clothes were becoming uncomfortably tight. You knew that your mother would get suspicious if you started asking for more clothes, so you suspected she hadn't realized yet that you were getting fatter. You could probably get away with asking for a couple new outfits. Though, your mother had often suggested you get a job so you could buy your own. That could probably be a good option to avoid suspicion. You knew if you didn't fix your clothing situation soon though, you wouldn't be able to hide your gain from your mother as you were bursting out of your clothes.