text: if you eat sugar does it make you slow? i play soccer and i want to know if sugar effects your stamina or speed during the game. sugar (as in the normal stuff you buy in bags from the store) is a good source of energy and rather than make you slow will in fact make you fast.  a better option would be glucose (one of the several different types of sugar) as the body breaks this down into energy very quickly.  many top atheletes use glucose to boost their performance.  it's best taken in the run up to the game and during the game as well.  you can take it in powdered form, diluted in water, syrup or as candy.