Im 16 and overweight help.?

okay so im 16years old im 5/4 like about 11 days ago i was 188 pounds and ive been eating only dinner just enough to get me full and drinking only water, now im 178 but im started to feel dizzy so i ate a bowl of rasin bran wit like 2 strawberries and this morning i was 176 and after i ate that i was 178 and still feeling dizzy i know its bad to only eat once a day but i REALLY want to get skinny and not have all this fat everywhere. need help.