I wonder if a strict keto diet is compatible with endurance-type activities, such as audax, in the longer term.
It is! ...for me at any rate.
Last year I gave the ketosis a hard push. I stuck to the rules militantly from the beginning of the year. I didn't start to see performance gains immediately. The weight loss was quick, but it took quite a while for my riding style on the bike to adapt to it. There were plenty of ups and downs to start off with. During the low points I seriously considered quitting it.
I got a good result on the 24hr TT (PB and club record) and had a very successful PBP, achieving a time that way exceeded my expectations.
While there are many factors to manage to ensure a good result on events like those I felt that the nutrition part was spot on. It is great not to have to have to carefully manage ones carb intake - too much = sick / too little = bonk.
Am I a changed man? Yes...well I was. As the year drew to a close and I didn't have any firm goals and events planned I eased off a bit: I don't miss beer, bread, pasta, potatoes, etc, but I have a real weakness for chocolate!
I'm trying to claw it back now, but it's not easy to make a such a dramatic change to one's lifestyle. I'd definitely recommend giving it a solid try out to see if it works for you...and if you feel that you can stick to it.
In my experience though you have to commit 100% to see the results.