I say both should get in the gym but that's just me
This is the correct answer.
There's also a little bit of bias in relation to being fat.
Maybe this is just my experience, but fat guys (from like 12-22) tend to be more "in-shape" than fat girls, because they are usually stuck doing athletic activities with their friends.
Every fat guy I know in elementary school, middle school, high school, and college was playing pickup basketball, football (tackle and flag), soccer, weightlifting, running, boxing, wrestling, or playing tennis/racquetball/squash. Because they're socially supposed to be involved in it.
Girls of the same age group that were fat weren't socially coerced into physical activity as much as their male counterparts. They also weren't as accepted by their peers as fat guys tended to be.