Not everything always plays out by the books though. In each individual case diet is a huge contributing factor, as are genetics. I have a very tiny male right now who never seems to gain much weight but also have experience with fairly large females that were constantly mistaken for boys since they were so big. Generally speaking, females do not cushion out as much as males do but that is what makes boys such squishy lap rats! I love my boys, so I guess I am fairly biased. Our rescued senior male is pretty plump but he makes an adorable snuggle bug.
My female sometimes gets a little chunky but she still manages to be small. From comparing her to other rats I see on here she looks itty bitty. She eats non stop and what she doesn't eat she hides so I know she's fed well. I guess she just runs it off. But even in size she's still really small
Are we talking about weight or size? Because a male rat is almost double the size of a female one. So if you feel your rat is too small, it's probably because it's a female and the rats you’re seeing around here are males. I also wished my rats were as big as some of the rats I see here, but their gender won’t allow it unfortunately.
Funny, I was thinking about this too recently. I know females are typically smaller than males and I never questioned my girls' sizes until I started watching videos on youtube. Either there are some truly large female rats out there, or all these people I'm watching have unusually small hands. Lol. My girls seem tiny compared to others I've seen.