The conservation of energy always holds true even when not clearly observable in machines that are less than 100% efficient. More often than not a machine will suffer energy losses (e.g. consider for a cooling fan: friction between the rotating blades, drag resistance in the air the fan is pushing around, resistance in the wire, and heat radiating/conducting away from the circuitry).
Well if the child weighs 44 kg then 44 kg. Do you mean if they weigh 44 kg in space to earth?
For one you’ll smell better, won’t be thinking when can i get my next cigarette, stop lung damage, skin will start to clear up