I fast for 24 hours (i.e. no food, only water and a couple cups of black coffee) twice a week. Contrary to popular belief this does not activate "starvation mode", it burns fat and keeps the weekly calorie intake low.
It's not particularly easy but it's not particularly hard, either. When I started doing 24 hour fasts, I would get shaky, tired, and as you mention, suffer headaches. For the first few times, you will likely not feel great. In my case, I adapted pretty quickly, and I don't feel "off" at all while fasting any more.
I'd also recommend the schedule that I use, which is to eat a normal dinner, and then skip the following breakfast and lunch, and then eat dinner at your usual time. You get 24 hours of no food, but it doesn't feel like a whole day. You also get a beneficial side effect: if you have no food intake in the morning, you don't get nearly as hungry later in the day. It's much harder to eat breakfast and then skip lunch and dinner than to eat dinner and skip the next two meals. Drinking a lot of water throughout the day will also help alleviate the "empty" feeling.
I'm not a doctor, this is not medical advice, consult your healthcare provider before undertaking any diet or exercise routine, blah blah.
I do this as well after being hypoglycemic and requiring food every 2 hours. I used the Lean Gains method which is also called Intermittent Fasting (IF). http://www.leangains.com/ Don't let the dude in the picture put you off. Really cool dude. I also experience better mental clarity and focus when I IF.