Dear yonder varlet
At a svelte 120 pounds you probably don't have a huge beer belly. With body modification not being an immediate remedy anyway, let's focus on clothing options. As already suggested you can use regular or strapless suspenders. You could also wear medieval clothing, which is secure but gives the impression of a securely trussed turkey. You first put on your shorts and wrap the waistband a couple times around the belt. Put on hose, either tight or baggy, per your preference. Next put on your shirt and then your doublet. The hose and the doublet both feature laces. You tie the laces together so that you can't lose your hose and so that your doublet won't ride up. Or maybe the type of meditation/combat robes that Steven Segal wears everywhere would be more to your liking? For laborers, bib overalls are the classic option