How small can a tiny house be?

The Nugget micro home from Modern Tiny Living is probably about as small as you would want to get at 102 sq ft or 9.5 sq m on a 12ft trailer. Inside there's a composting toilet and 30 inch x 30 inch shower, and a mini-fridge and hickory butcher block countertops. It's designed to be off-grid with a 100 gallon fresh water tank solar batteries/panels, and a propane tankless water heater. Marketed more as a "weekend getaway or travel companion", living here full time (especially without a cooker) would be tricky.