I saw some women jogging and doing stretches and one was wearing tight, skinny cut black pants that I assume were Yoga pants, but she was wearing a regular belt with them. Up until now I never heard these existed. Are there yoga pants with belt loops, possibly made so they can also be worn at work?
It was probably her own "style". Yoga pants are comfy and already have a stretchy waistband that form to your figure so you don't need a belt to hold them up. Quite honestly yoga pants with belts is verrrrrry weird, especially during exercise. I can only imagine how uncomfortable that is.