You will need the bell bottom pants mesh for the slimmer bodybuilder from 
here for these to show up in your game. 
Here are another 8 basic casual outfits for the slimmer bodybuilder consisting of jeans with an un-tucked button-up tee. 
They are organised into 2 sets with 4 outfits in each set. 
Set 1.
 Set 2.
 Credits: 
Mesh - Marvine