Welcome to HCM,
Night discharge is very common particular in teenagers and youngsters.
Now a days due to viewing sexy porns,videos on computers a person remains excited sexually whole day resulting night discharge or masturbation
Nothing to worry,if sperms not coming out by these ways are destroying by the body after some time so the idea you got of loosing weight and energy is more or less psychological.
Take nourishing diet,do not go for sex exciting movies or porn.
Before going to bed be fresh,see good entertaining sereals,read good books and prey the god for good sleep.
Ok and bye.