That is not true about Keys.
This "debunking" has been debunked many times. Keys was a good scientist and only matched data that were comparable.
For the record, I am not a vegan, a vegetarian, or an adherent of any particular diet regimen, except the one you can live with for the rest of your life, with a health-promoting metabolism. For some people that's low carb, for some, not.
About insulin resistance, all I've gotta say is that there are knowns, unknowns, known unknowns, and unknown unknowns. So let's all be a little humble and bow down before the amazing complexity of the human body. With that in mind, here's a few thoughts:
There have been many populations that are healthy and non-obese whose staple diet has been starch. So carbs per se don't cause insulin resistance. (I think it's important to note that these people are invariably very active.)
"I think he tries to over-simplify the issue when he says carbs don't cause insulin resistance meat does. If it were that simple, some cultures, such as the Inuit should have had ridiculous type 2 diabetes rates."
I agree that he is oversimplifying massively but just for the record: the Inuit were adapted to their extreme environment (1300 calories a day expended just breathing!),
and the chemical composition of the marine mammals they ate was different from land mammals. Marine mammal meat has lots of glycogen. And they ate as many plants/veg/fruit as they could, gorging themselves on this during thaws.
Back to IR, there is some evidence that high fat is implicated. I could do a "proof-by-Pubmed" but then everyone would say I am confirming a bias. And maybe that would be true. But anyway, here's a couple of studies:
Recent data suggest that IMCL are specifically harmful when combined with reduced mitochondrial function, both conditions that characterize type 2 diabetes.
(That IMCL stuff particularly interests me, because I think that is where it all starts, before the liver & pancreas get blocked up.)
OK, it's just mice, but still.
I'm not here to mess up anyone's great experience doing LCHF. If you're losing weight & getting good results with that, go for it. But facts are facts (until new ones come along) and my take is that the disaster of the modern diet is massive intake of "carbage"
plus high fat,
plus zero movement. = METABOLIC DISASTER.