I had colon cancer in 1996. My main side effect from chemo and radiation was severe diarrhea. The only food I could begin to hold in was rice soaked with chicken broth. I lost about 40 pounds over the 7 week period of diarrhea.
After the end of the diarrheal period, and after the internal radiation burns healed up, my doc said I needed to gain weight. That was not a problem at all, because I was always hungry and everything tasted wonderful. After 3 months I had gained all the weight back, and then some.
The treatment was in the neck so my taste buds were racked and I couldn’t detect sweet for 3 months, which reduces the enthusiasm, but I managed to get back in shape and climbed a 14er several month latter.