@sandyjr, I am confused about your question about intermittent diet and reference to your oncologist. Primary Sclerosing Cholangitis is managed by a liver specialist or a Gastroenterologist.

Here is some diet/nutrition information specific to PSC.
Primary Sclerosing Cholangitis (PSC) is a rare liver disease that damages the bile ducts inside and outside the liver. I want to introduce you and your daughter to 'PSC Partners Seeking a Cure'. PSC Partners Seeking a Cure is a nonprofit organization with various programs to give support to patients, caregivers, and to educate patients and the medical community about PSC. Here is what I read about diet-
"There is no specific PSC diet and most patients do not have to make any changes, except to continue to eat in a healthy, sensible way. However, many PSCers have related digestive issues, such as ulcerative colitis and other gastrointestinal problems, and need to stick to a specific diet, as advised by professionals."
https://pscpartners.org/about/treatment-options/nutrition.html

Another resource is NIH where you will find this information: Eating, Diet, & Nutrition for Primary Sclerosing Cholangitis - What should I eat if I have PSC?
https://www.niddk.nih.gov/health-information/liver-disease/primary-sclerosing-cholangitis/eating-diet-nutrition

@sandyjr, PSC is a rare disease, it is a progressive disease. I was transplanted in 2009 due to PSC. Throughout my entire PSC journey, my GI (Gastroenterologist) monitored my condition with routine labs and consults. Without any additional conditions, I was advised to maintain a healthy lifestyle with a heart healthy diet and to get regular exercise. He guided me and answered all of my questions.

Does your daughter have regular visits and labs with her doctor? Is she an adult or a child, for example, How active is she in maintain her own diet and health management? What has he advised about her dietary needs?

I agree with you on "the old food pyramid". I have EPI (yet another GI disease that is hard to diagnose and hard to adjust diet to. I eat keto and my only issue is sometimes high fat is a "ahem" problem. I have adjusted to "medium fat" (typically less around 50% of my calories) and still stick with 20-40 grams of carbs. My carbs are salad or non-starchy vegetables. I also fast (one meal per day every day and one whole day each week). Nothing like it to reboot the GI tract and improve energy. I really appreciate my food after a fast and it costs NOTHING.
This may not help your daughter, except that relying on old nutrition information leads us down the wrong path. It sounds like you've already adapted to non-processed food and that helps alot. Processed food is bad for the body and only makes you hungrier.
Probably the best key to any diet but especially one that helps deal with a GI disease is nutrient dense, high quality, non industrial food. I wish you both the best of luck.