a 100 pound girl

my sister told my mom that she wants to become a vegetarian. i suggested that my mom cook brussel sprouts with squash just for her and no one else. she laughed at what i said and waved me off. i don't think she realized i was being serious. every day at the dinner table, my parents ask my sister if she wants more food and her response is "no" every time. i think they're real worried about her because she's taking a gym class right now and her weight is dropping and she stresses out about school more than she should. once, i caught her standing in the bathroom trying to see how far her jeans would move away from her stomach. i realized that the jeans that fit her in 10th grade are a lot bigger now. she told me she doesn't like eating which has forced me to believe that she's from neptune because no one on earth does not not like eating. there's no such thing. i also think that my mom is going to start hand feeding her so that she can observe the amount my sister eats. did i mention that we're twins who have a 20 lb weight difference?