This is patently false, and even if you are restating something from I book, I wouldn’t. I would also double check that info as sugar isn’t the most important but the most dangerous.

Perhaps you meant carbohydrates which isn’t as blatantly dangerous a statement, but also not necessarily true and it depends on your genetics.

Fats especially healthy ones, like carbs, are likely more important due to their impact on brain heath and cognition.