You will need the bell bottom pants outfit for the slimmer bodybuilder from 
here for these to show up in your game. 
Here are 8 casual outfits for the slimmer bodybuilder, consisting of jeans with a hitched-up, rolled-up sleeve top. 
They are organised into 2 sets with 4 outfits in each set. 
Set 1.
 
 Set 2.
 
 Credits: 
Mesh - Marvine