How many serious athletes train like this though, do you know many? Surly by sweating more you are losing alot of minerals in your body by sweating so much and then you are not reaplacing them as you are only usign water to rehydrate yourself. Yes I would train in sweats if further down the line you are goign to be training/playing in an enviroment which is going to be hotter then you currently train in
and in relation to the fats are quite important espeically for men as it helps in the production of hormones including testosterone so why anyone would want to cut them out I don't know,