I ate only potatoes (+oil/butter and spices) for years and was happy (I really love potatoes) but then got too tired of washing potatoes many times a day (you h

I ate only potatoes (+oil/butter and spices) for years and was happy (I really love potatoes) but then got too tired of washing potatoes many times a day (you have to wash them because even a clean-looking potato has a serious chance to have a particle of sand stick to it and that's very unpleasant to bite). My mass (rather humble) never changed during those years, mo matter how much I ate, slept or moved.