Any diet restrictions with radiation? What were your side effects?

A. I didn't get any diet restrictions with my Salvage Radiation Therapy, not sure if they give any for the primary treatment radiation. It's going to be important to be as "regular" as you can so I eat mainly fruits, veggies and nuts.

B. The radiation gave me a kind of burning sensation in the anus and made me tired. I have an ongoing battle with a hemorrhoid that flared up as well. That was pretty much the extent of it for me, those things disappeared in about a month after completion. I was told I could expect diarrhea as well, I only had one or two bouts, given that it might just be coincidence. Everyone is different.

Are you considering a Space Oar or some other type of protectant?

I had 39 IMRT sessions starting in May 2022. I watched what I ate but didn't change much from normal diet. There where some mild bowel changes (I'll spare you the details). Fatique was tolerable. To sum up:
Keep your lazy boy close and the bathroom closer.
Just kidding. It wasn't bad at all.
Watch out for the month or so after, the Fatique was much worse.

Meeting with radiation oncologist next Monday for mapping so many unknown?

Fire away any questions you have, but, my radiation was salvage radiation, so, I'm guessing less of a dose. I did still have fatigue as suggested by @spryguy but mostly during the last 10 or so visits then a couple weeks after.

I'd get zapped around 9, go tot the gym for a couple hours, eat lunch and out like light for an hour or so! 39 visits seems like a lot from this end, but, for me, it went by fairly quickly.

I am unsure what it is called post radical prostatectomy first 8week PSA less than 0.1 surgeon failed to show for 3 followup appointments different reasons?? I know right!! Urinary infection with catheter sent me to GP for help.. then informed Surgeon had been removed from practice At hospital and office closed??? No explanation in the confusion GP order another PSA from hospital lab at 3month mark risen 0.2 received referral to new Urologist scheduled PMSA PET SCAN results clean and onto Radiation Oncologist 4month PSA 0.331 started ADT 2 months 0.05 scheduled for Radiation 40treatments doing Mapping next Monday
The biopsy from RP clean edges neg nodes, seminal vessels and the extra ??? No signs of any problems.. so microscopic..
I have already lost about 25 pounds I do work on the farm every day but eat well, being told no fiber really no fresh fruits or vegetables kinda fear more weight loss? Curious to diet requirements..

That makes no sense to me, I was told the opposite. I eat mostly fruit and veggies with maybe 4-6 oz of protein a day. I'd confirm that if I were you at this point.

The 40 treatments will go by pretty quickly, I know it doesn't seem like it now but it'll be in the rear view before you know it.
Best of Luck to you!

I had CyberKnife, five sessions. I was on a low-fiber diet for aiming session and then the radiation sessions (to shrink the rectum so it's less of a target), plus a Fleet enema before each session. The diet's not great, but it's worth it.

How did you decide to do CyberKnife? I am haven’t heard much about it. Is it best for less aggressive cancer? Did you have to take hormones? What are the side effects?

So the diet is specific to the treatment option ? As opposed to the disease I guess?

The purpose of the diet is to shrink the rectum so it is less of a target for stray radiation, so I think it would be helpful for any type of radiation.