As regular readers of Dr. Andy know, I've embarked on a crazy diet: one day per week I fast, taking in only non-caloric liquids like water and black coffee.
I've been going for about 5 weeks and have lost 8-10 lbs so far in total (this is base weight, not what I way after fasting which is down a few lbs due to water loss). I try to weigh myself every am and the last 3 days I've been in the 202-204 range
I think this is okay, but I've been running and training more (145 miles running in June) and eating better in general, so I'd probably have lost some weight anyway. I am running dramatically stronger and faster, but how much this is training and how much weight loss is hard to know.
The fasting itself is pretty easy. As I've noted the social part is much harder than the physical part. You notice you are hungry, but the hunger itself isn't too bad. But at dinner time it is weird to just sit there and not eat. It is also an effective alarm clock as I'm eager to get up and break the fast.
The one thing that is hard is working the fast day around training. I've noticed that working out the morning of the fast if anything makes me less hungry, but if I do too much, fasting dramatically slows recovery since those glycogen depleted muscles are sitting around not being replenished. The day after, I notice I'm weaker, too, so you have two consecutive days where you can only train gently (the runs post-fast, even after eating a bit, are an adventure and even if I wait until the evening, I still notice I'm not as strong). This could be an increasing problem as I ramp up training, with the goal of a 100 mile race in the fall.
I've read a bunch of crazy fasting sites on the web and some suggest taking vegetable juices to give a few calories to keep you from putting your body in starvation mode and I might experiment with that.
I'm fasting today and it strikes me that this is the perfect diet for those who travel a lot. Unless you are really careful, eating when careful is a ton of unhealthy calories which you don't really enjoy (rushed fast food or airline meals). Fasting just on travel days (or while travelling only) might be really effective.