Depending on your age, you may be having a growth spurt, in which case you'll be hungry all the time until it's over. Additionally, you may want to evaluate your protein and fat intake, as both of those nutrients, when consumed in sufficient amounts, can stave off hunger longer than carbohydrates can. Finally, you may want to go to your doctor to make sure it's not a thyroid/adrenal gland issue or a blood sugar regulation problem. In the meantime, definitely eat when you're feeling that depleted!