If a boy consumes only rice and potato in his daily diet, how will it affect him?

it could make you gain alot of weight the carbs and calories are really high so you have to be careful of that kinda diet it probably won't be as nutritious as you would thing the best diet you can really stay healthy and not having that much carbs sugars and calories cutting most out of your diet this is what a good diet consists of high protein and good fiber