It's called having some chub, not necessarily chubby, but on the brink of becoming chubby.
Chub is the sign of getting chubby and a good reminder/warning to cool it on the snacks and walk off the extra weight before it's too late.
Guys ask for "thicc" which can give women the wrong message to keep getting bigger, and soon they become fat, not even chubby, just plain old fat.
When women get self conscious and scared they're getting fat when they're actually getting chubby, that's when they're at their best.
They have a small tummy going on that isn't necessarily noticeable at first, especially when they have some decent clothes to hide it well, but behind it is the ideal female body type where they're not chubby yet and still have some semblance of a healthy looking body that they can easily get back in a week or two.