If you need to go out a lot and it's really hot, make sure to drink plenty of water at each meal before sunrise and after sunset. Dehydration can be a risk. Where I live, my fast lasts from 5:00 AM until we open at around 8:30 PM. This will differentiate depending on where you live. If you really want to be exact, you can look up the Fajr and Maghrib prayer times for your area. You will eat around Fajr and then you will fast until Maghrib each day for 30 days. You may experience headaches/migraines due to a change in eating patterns. Also, you may wish to consult with a doctor if you need to take any daily medications or have any health conditions. Because your meals are spread so far apart during Ramadan, you may experience some weight gain due to over eating at the end of the day, but this honestly varies from person to person. Good luck on this endeavor.