I just read the book: "Volek & Phinney's Art & Science of LC". Fascinating, but then it raised a serious question that undermined my understanding:

page 86: "pretty consistently, as dietary fat percent is increased from 30% to 60% in animals and in humans, insulin sensitivity does get worse. But once above 60% of energy as fat, which typically translates to less than 20% of energy as carbohydrates (assuming 15-20% from protein), insulin resistance turns around and starts to improve."

"does get worse"?! They did describe an "island effect" where going half-way low carb might not get you there (better insulin sensitivity and other beneficial effects). But, that both duration of diet (at least 2 weeks long) and degree of carb restriction were important.

This is very confusing and yet is very important to understand. So, cutting out that baked potato might be making matters worse for someone w/ IR or T2D? That is, unless they're willing to go full ketogenic?

The book is acknowledging that increasing fat does cause a worsening of IR. Can anyone provide any insights?