In the 70s, it was the Pritikan Diet which was low fat with no salt or sugar. Then there was Sugar Busters and the Zone. And of course, there was Atkins. Most of these diets make some claim to eating like ancient man and that our digestive systems cannot handle modern food. That may all be correct.

What I have found is that getting the right balance of fat, protein and carbs does make a difference but so does counting calories and having discipline to not eat. I like to ride in the morning without eating breakfast. First, there is more blood available for power production since one is not digesting anything. Second, it trains the body to burn a greater percentage of fat which is a good thing especially if you are a RAAM rider or Stage racer.

This morning I did flying kilos at above pursuit race pace and I did the first one on an empty stomach. I did a shot of PowerBar gel which is glucose and fructose. What I have learned from our nutritionist is that eating any sugar will cause an insulin reaction and inhibit fat burning. However, the kilos were going to be fueled predominantly by glycogen, hence the gel.

I have not been able to find any literature on fat burning using less oxygen. In fact, it seems to be the opposite. However, we all know that if one researches optimum cadence, one will find that 80 to 100 is optimum yet many pros and amateurs are doing time trials at over 100 rpm and think it is better.

For my breathing to become a limiter, I have to be going really hard. What happens to me is that my legs start to feel the pain and I have to tell them to STFU. At the point I go anaerobic and light the fuse, my breathing increases and gets gaspy and at some point I blow and have to reduce power to recover.

My question to OP is where is the supporting research that says that oxygen requirements are lower in Ketosis? Also, is it not feasible that better fitness and lower requirements for oxygen is due to training i.e. OP is getting stronger?

An example of bonking is a marathoner collapsing at mile 20 and cannot go on. He is disoriented and cannot stand. OP's bonk seems like fatigue. But I may be wrong.