Hey Deborah.
I too have heard good things about fasting before chemotherapy, though my gut feeling is that it’s quite an individual thing. As @Darcy mentioned, the anti-nausea medications also work well at times.
I know quite a few people with cancer in their past - my mom, dad, grandmother, a cousin, step-mother, father-in-law, etc. The common thread is that the anti-nausea drugs have really improved over time, even in just the last decade or two.
Ten years ago I had an infection in my back, two vertebrae that were literally shrinking, getting eaten by something - bacterial or viral. Never found out which, but for nine weeks went to the hospital twice a day for intravenous infusions of antibiotics, which apparently fixed me up in the end. I sat with other patients every day, many of them receiving chemotherapy, and everybody had had good or excellent results with keeping the nausea to a minimum.
No doubt you’re already on this, but keep communication open with the doctors; sometimes it takes a few tries to get things right. Hope I don’t sound like I’m pushing anti-nausea drugs too much - what I’ve been impressed with is that what was often a truly wrenching experience is frequently mitigated a good bit nowadays.
Good luck to you, and good thoughts always.