I fast for 40 hours before chemo and then eat only a very light snack (<100 cal) the 2 days that I'm on the pump. I have done this for my last 9 chemo sessions. I told my oncologist and 2 liver surgeons, since I don't wont to compromise the rest of my body, and they are ok with it (although not encouraging it).
I do it because otherwise I don't think i can take the chemo. My first round of chemo after colon resection was horrible, I thought I would die. I was not fasting them although I knew about the research. I even contacted the PI of the group doing the research and he kindly replied back with instructions on the fasting. I finally decided not to fast at that time because I was underweight.
When I was diagnosed with mets I decided to try the fasting, and it has been much easier since. I recover well from the chemo rounds. I am still underweight (guess is becoming my normal), so it was a difficult decision. But giving my terrible experience with the first chemo round, I will be even more underweight if I don't fast. Now at least I am able to keep my weight more or less stable from chemo to chemo session. Lose a little during the fasting and then gain it back since my appetite, smell and taste stays good.
I would recommend anybody starting the fasting to do it slowly, as in only a few hours to start with and then increase it. The first time was really difficult, so I ended up having a snack. And obviously, talk to your doctors first about it!
Clinical trials are going on at the moment and recruting, here is the one at Mayo Clinic:
http://clinicaltrials.gov/show/NCT01175837