Shirts definitely can is well. This is one reason aloha shirts become a go-to choice for some men as they get older — the cut can help hide an expanding waistline.
Oh yeah. Horizontal lines look wider, vertical lines look taller, dark shirts hide flubber, and form-fitting shirts when you're overweight look bad.
Speaking of which, I need to lose 40 lbs. to get from a size 40" waist back to 32-34". I wear bright, geometric or paisley button shirts unbuttoned over interesting t-shirts.