I've actually experimented with calorie restriction and it seems like the less I eat, the better I feel. I am a teenager, so perhaps it's not fair to make a comparison to adults, but I feel better on an empty stomach than on a full one. I've never actually tried to fast for more than three days because I'm close to an anorexic as it stands. I am by no means an anorexic, because I don't have the same mental disposition, I reduce my calorie intake not to look better, but to feel better. Here's the odd thing, I used to be slightly overweight, 15 pounds-ish and I decided to lose the excess. I did manage with a combination of low food intake an a tad bit more exercise. Now I'm at a healthy weight and I feel better than ever. The trouble is that I lose about 50 grams of body weight on average every day, even when I eat well and live a sedentary lifestyle. It may not seem like much but at the end of a week, I lose a substantial amount of weight (something close to a pound). I then have to eat more during weekends to compensate for the energy loss, but whenever I do that I feel awful and sick and wish I ate less. My parents think I'm an anorexic and I don't blame them. My weight once dropped below 49kg (108lbs) and that's low for someone who's ~170cm tall. They tell me to eat more and as soon as I do that, eczema breaks out on my hands, I get cold like symptoms in the morning, and I feel awful. I go right back to eating less (it's a sort of reverse addiction) Every once in a while, it is good to escape the excesses of society, and simply consume less.