My wife and I did this crazy little experiment in February. The excellent new magazine Aeon has published an account I wrote of it:
The plan was to go a full week without eating or drinking anything except water. Lest our bodies react to this insult by trying to slow down our metabolisms, and we end up just lying around and not getting anything useful done all week, we also planned to stay energetic by engaging in vigorous physical exercise for at least a couple of hours daily during the fast. Neither one of us had ever done anything of the sort before.
Since my wife had a week’s break in February from her work as a schoolteacher, we decided to try our fast then. Our preparation was pretty minimal. I would keep a journal in which I would record my weight, blood pressure, activities and, several times a day, just note how I was feeling. We bought some emergency supplies in case one or both of us ended up feeling ill or fainting: some energy drinks, a couple of bars of Swiss milk chocolate, some fruit, and some bread and cheese, and put them in the refrigerator. My wife also told me to stop locking the bathroom door from the inside, just in case she needed to rescue me.
On our final day before beginning, we measured our weight, blood pressure, pulse rate, and waist size. My wife and I don’t normally eat breakfast (she has a cup of coffee and I drink a Coke Zero — yes, yes, I know it’s bad) but that day we had a light lunch and in the evening we had an early dinner of chicken, potatoes, broccoli, cauliflower, and brown rice. And some chocolate pudding. And then we stopped eating.