sugar

My computer has been working strange since 23th ,so now i cant type japanese letters at all . anyone please let me know how to fix it .

anyway , i write in english today . Today i realized that having too much sugars makes us tired . i havent had sweets in this month but 2 days ago i got the cakes from my friends and i overate them a lot . Of course the weight gain and i felt really tired at the gym today . i couldnt lift the weight i usually could lift . just a little sweet is okay to have but a lot .
So i have really decided not having too much sweet .
i would like to know what is happening in our body when having too much sugar .