...
"So I was thinking of food that keeps me full, and doesn't add weight to me, and I couldn't really think of something better than... well... uuuuhm...", your sister spoke quieter by the word.
You just looked at her confused, waiting for her to finish her sentence.
"...Tinies... I mean tinies.", she said ashamed.
From your flabbergasted look, your little sis realized what she just said and immediately felt stupid. "Okay no we can't do that, I was just joking", she said, underlying her joke by an awkward laugh.
"This isn't a joke right? This really was your plan?!", you said still perplexed. For a moment you thought about it. That's why she asked specifically you for help. Not because you were good with loosing weight, more because of your special squishy attitude.
Theoretically tinies can be eaten safely. The stomach acid doesn't hurt them, even if it dissolves them into a mush slowly. An eaten tiny person would just have to go out the "natural" way, and would have to rely on their host to remember checking the toilet.
"I know I know I know how stupid that is. But I really have to loose weight fast for my next cosplay", your sister tried to explain. Giving you her best puppy eyes she could do she said, "It would only be for two weeks, I pinky promise".
Before you could even think of what to say she added, "And besides, you already told me you are willing to help. You also forgot my birthday, so you won't have a better present."
*****
After Serena persuaded you for a whole hour, you finally gave in, even if this whole plan sounds incredibly dumb. You unwillingly had seen the inside of your sister plenty of times, thanks to the many accidents that have happened in your life. So those extra fourteen times won't add to the pile. Finally agreeing, you said, "Serena stop trying to convince me, i'm in.
Your sisters face lightened up with pure joy. She hugged you very firm and said, "Oh Tim thank you sooo much" giving you a sisterly kiss.
"Let's just get this over with", you said.
"Someone seems to be eager to start aren't you? To be fair it has been a long time since you have seen my stomach from inside. You feeling homesick?", Serena chuckled. She was thinking of how she's gonna get you to your desired position.
After a short period of reflection, she looked like she settled on something...
1. Serena prepared a healthy smoothie with a certain extra ingredient...
2. Serena just swallows you whole, flushing you down with some black coffee...
3. Some other recipe ideas