Anyone who does physical workout?

Instead of eating at your breaks, get up and take a walk, even if it's just around the building. If you are really hungry, take a healthy snack you can eat while you are walking, like a banana or some other fruit you like. Try to stay away from junk food that has little nutrition. When you get off work, take a short nap if you want, and then another short walk after you eat. You may not feel like doing that, but you will be surprised how it will energize you. Exercise will increase your metabolism so the calories you consume will burn off quicker. If this doesn't help, you might consult a doctor to see if you have some kind of physical ailment that makes you so tired all the time.