Do women wear underwear under there workout leggings at the gym?  Should I insist that my lady wear some under hers?

No let her give the pervs a show

No if she’s comfortable not wearing underwear beneath her leggings - leave her be. It’s not really your business. There are seamless thongs that are made for activewear but if you can see the lines that looks pretty tacky. Most Workout leggings are made to be worn with NO underwear for comfort. Back off and don’t be a dictator. 👍

If she wore seamless underwear you won't be able to tell any way. What does it matter? At the gym you can see every persons bits. 

I already talk to your lady when we were in bed the other night and she said she doesn’t like the feeling of thongs or panties, that’s why she always takes them off, especially for me. 😉

You don’t have any right to insist it’s her choice.... and how do you even know this? I chose to always wear a thong you can not see the lines any way! It’s a good habit to wear something underneath but it’s her choice I’d say

Some do; some don't.

It's more hygienic to do so.

It's not your place or privilege to tell her to what to wear.

Lousy trolling, dear.

It’s her choice, not yours

it should be her choice 

No, you shouldnt insist. But damn if she doesn't put anything under the GYM clothes shes nasty affffff

It’s her choice, not yours