"Sounds great, but is this compatible with"

Yes. I guess I can't speak to "bodybuilding" but I have maintained a high level of powerlifting output for years on a schedule of IF (two 16 and one 24 hour fast per week).

In fact, I would go so far as to say that many activities are enhanced while in the fasted state - my distance running (admittedly short, 4-5 mile runs) feels easier and I feel lighter on my feet and I also feel lighter and quicker in my BJJ practice (even though my weight is the same).

I usually do my heavy weight training while in a (16 hour) fasted state, immediately followed by a high protein, 1000+ calorie meal.

The only adjustment I have had to make is that the meal immediately following my 24 hour fast needs to be contain a lot of fiber. If you shut down your digestion for 24 hours, you don't want to fill yourself back up with cheese pizza or a huge steak.

YMMV.

It really isn't a problem once you're adapted which takes a few days normally (my experience). These guys seem to have no problems with their physical strength on a ketogenic diet: http://www.fatchancerow.org/ - so if this isn't fake (which I don't think) most daily energy demands should be satisfied.

Basketball Hall of Famer Hakeem Olajuwon of the Houston Rockets is an observant Muslim; a Reddit post [0] says his game performance dropped a bit during Ramadan, but he still managed to lead the team to two consecutive NBA championships. (Apparently Ramadan never occurred during the playoffs during the years in question.)

[0] https://www.reddit.com/r/nba/comments/3yvhf2/hakeem_olajuwon...

My longest stretch of keto (and lots of IF) was about a year. I lost around 100lbs. During that time, I rode a bit over 3000 miles on my bicycle, longest ride was 120 miles in a day (purely fueled by keto, coffee, and water - do not do this unless you have supervision by a medical professional). Keto is well known by some ultra-marathoner (insane people) buddies of mine.

Being in the ketosis state is amazing for intellectually intense work.

Regarding bodybuilding, I will copy and paste a reply of mine from another comment:

Keto is not exactly compatible with anaerobic exercise. If you're lifting or performing a mix of aerobic and anaerobic (e.g. running / sprinting intervals), your muscles still need some glucose. I'd suggest checking out the cycling ketogenic diet (carb cycling) - it will allow you to refuel your muscles' glycogen stores, allowing anaerobic exercise (weight lifting, etc) while maintaining ketosis 99% of the time (staying lean). Also check out alpha lipoic acid supplements, it will increase the ratio of glucose provided to your muscles vs fat storage during your carb load. Go get ripped :)

Keto and IF can be very dangerous if you don't know what you're doing. I'd suggest getting regular blood testing with your doctor while adjusting and figuring out your routine and meal plans.

Yes, you just need to account for that in your total caloric intake. Your re-feeds are going to need to be bigger.

I've done HIIT in a fasted state just fine, and intellectually I actually feel sharper when fasting, which makes some sense. If we couldn't focus our senses while running on stored fat, the human race would have died out a long time ago. There's some data corroborating this, albeit small studies: https://www.ncbi.nlm.nih.gov/pubmed/18779282 https://www.ncbi.nlm.nih.gov/pubmed/7473300

Anecdotally, if I have something important to do and it's before lunch, I'll delay eating as it seems to slow down my thinking. Not exactly evidence, but thinking on an empty stomach seems to work for me.

You can indeed get very strong and very lean with Intermittent Fasting. This is a goto site backed by plenty of good research.

http://leangains.com/

The leangains subreddit has good summaries of the leangains site, without the Jordan Peterson stuff that the guy has added lately.

https://www.reddit.com/r/leangains/

Yes. Your liver glycogen and muscle glycogen will be fine. Your body can convert protein to glucose when it is needed and use ketones for everything else.

you NEVER want your body to convert protein to glucose. it's your body's last resort of energy and is very destructive.

Gluconeogenesis is not the same thing as muscle catabolism.

Lots of people do Ramadan while bodybuilding, playing international level soccer (football) while fasted including no water.

That's not really fasting in a metabolic sense, though. More like time restricted eating.

It might be, anecdotally I know of a few high performing athletes who are now keto all the way. That said, it is utterly incompatible with my desire for milkshakes and candy bars, both of which are things I crave at the end of an intense bike ride.

Yes. Just increase the number of calories you consume during the feeding window.