The Cat Ate My Gymsuit - Paula Danziger

Ninth-grader Marcy Lewis is a smart and sensitive girl who nevertheless lacks confidence. Being plus-sized, she is embarrassed to draw attention to herself, and she is failing gym class due to her reluctance to change clothes in front of the other girls (resulting in numerous creative excuses for why she doesn't have her gym clothes, such as the titular "the cat ate my gymsuit"). Her verbally abusive father Martin belittles and criticizes the entire family, while her nervous mother Lily encourages her daughter to ignore his behavior and try not to set him off, leading to Marcy's inability to talk about how she really feels.