I have clients who fast one day a week. Gives the digestive system a break and allows cleansing .. this is combined with a clean healthy diet of course.
I finish the 3 day fast with a colon cleanse.
People don't appreciate just how hard they overwork the GI. I'm not saying I'm turning vegetarian or anything, but I almost eat no more red meat because that stuff takes a fair bit of processing power to be broken down and pushed out the pooper. I'm not against it at all and I'm not a red meat fear mongerer, but you don't need a solid kilo of red meat per day and you don't need to eat it 5 times a day.
Fasting and/or intermittent fasting is a good way to enjoy these things without putting the GI tract on the chopping block. We weren't made to be eating things like red meat multiple times a day. It's extremely nutritious but we don't need such a crazy overabundance. I found that my shits have been way better since intermittent fasting and cutting back on things like red meat, which is usually something the all-day-grazers/6-meals-a-day-crews like to promote like it's going out of style.
Lots of veggies are great, especially coming off a fast. Easy on the body and you can cook them to taste amazing. I used to shun veggies and figured a multivitamin gave me all I need, but I'm embarrassed to admit how wrong I was. I've found lots of ways to make them quickly, make them way more than palatable (they taste awesome) and it does the body good. Keeps you from over-eating as well. You can go to town on a huge plate of veggies without remorse. After a big fast I'll slowly add a bit more meat back in and my stomach doesn't gurgle and turn like it used to. I'm getting way leaner and feel stronger too, so eating properly isn't a submission or compromise at all.

What do you like eating before and after fasts, sev? And how do your clients respond? It can be a big change for people, so you probably see a myriad of reactions. Would love to hear more. I'm a fucking newb when it comes to eating properly as the bodybuilding propaganda was the only commitment to food I ever made.