What I’ve come to believe is that not fatmax is the ultimate endpoint but the breadth of the fat ox curve:
https://www.alancouzens.com/blog/Kona_fatburn.html
And to develop this breadth, which is characteric for a massive diesel:
pro vs moderate active
one has to work on the edge. Which is still the base. For a beginner or someone with poor engine fatmax may be equal to the outer edge, but once you’ve developed an engine this edge moves to the right. And this agrees so well with all my pro strava hacks where they do their “base” and why they do so much lower tempo. It’s this outer edge.
These days people are scared of carbs. Base training to them means only fat. However, once you go the edge you burn plenty of fat but you also need carbs. Therefore, chronically riding base without carbs may stall your development to move this edge out.