Workout yesterday. waited 3 hours before eating. 2 meals totall yesterday. really tired with headache today. to little food yesterday? and why?

Workout & meals: Even if not working out (but especially if you are) you need more than 2 meals a day. Depending out their goals, many people will have some carbs (veggies, complex carbs) & protein before a workout, and then again after. Generally you want to eat something healthy (not junk food) every 4-6 hours at least, stopping eating 3 hours before bed time. Your body needs fuel and care each day.