I have held off on posting here as the topic has bounced all over the place. I look at the discussions you have but to me it all comes down to what is your goal. Diet vs bike performance. I see your last comment talks about teeth. Here is my 2cents.
I started to cycle regularly when I was told I need to lose weight. So i dropped 500 calories a day and for the next 15 weeks I dropped 30 pounds. I didnt fuel on the bike till near the end as I did struggle on some rides with no fuel. So I did this work to lose weightā¦hit goal weight and then went back to my new diet which was no sugar off the bike. Food intake went back to what I previously did. I fueled my rides. Not to the high levels but more like 60g an hour.
So now I was riding regularly, eating my healthy meals each day and consuming carbs on the bike. My weight continued to drop. I had to start eating more.
Seven years later I consciously have to eat more to maintain my weight. My weight is one pound more then what I dropped it to as my goal weight. This is where I have stabilized. I fuel the rides that are more then 90 minutes. I may fuel some of the others but it often is just some electrolytes or how I feel. My own take is I do everything I can to reduce my RPE. If my RPE is low I ride a lot easierā¦
So my take is fueling my zone 2 workouts only helps me. I fuel to make my rides feel easier. If I dont fuel I am starving after my ride. I am now in my early 60s. My ftp has improved. Improvement roughly 30% higher then when I started riding 7 years ago. No idea if I will keep improving. I dont think what I did to lose weight was smart. Too much too fast. I should of just let my body adjust over time from the diet changes at a slower pace. The cycling accelerated what I was doing. I personally dont see the benefit to not fueling long zone 2 rides other then crash dieting. I did it and wouldnt recommend it.

