Morg the low carbohydrate high fat diet decreasing insulin sensitivity has been discussed here in the past, also berardi mentioned it in a couple of his articles too.
here is one
"RW ? Does insulin sensitivity vary or change?
JB ? Insulin sensitivity is unique to each individual but the cool thing is that it can be manipulated by exercise, diet, and supplementation. And that’s what I do with my clients to dramatically change their body composition.
Both aerobic and resistance training greatly increase insulin sensitivity through some different and some similar mechanisms. In addition, supplements like omega 3 fatty acids, fish oils, alpha-lipoic acid, and chromium can increase insulin sensitivity. Finally, moderate carbohydrate diets that are rich in fiber can increase insulin sensitivity.
On the flip side, the low-carb, high-fat diets that have become popular can decrease insulin sensitivity. That’s why none of my trainees go on no-carb diets, unless they’re dieting down for a show and then they’ll do occasional no carb diets every few months for a maximum of 3 weeks at a time"
and this from massive eating…
“On the flip side, stimulants like ephedrine and caffeine can decrease insulin sensitivity due to their effects on metabolism. Furthermore, the low carb, high-fat diets that have become popular can also lead to decreased insulin sensitivity. That’s why my trainees don’t take stimulants or go on no-carb diets (unless they’re dieting down for a show and then they’ll do occasional no-carb diets every few months for a maximum of three weeks at a time).”
Ummm now for some studies
“The available data support the idea that consumption of diets high in total carbohydrate does not adversely affect insulin sensitivity compared with high fat diets.”
this refers to what cyco was saying about glycemic index
Now I realize that some of the studies are on rats, but there are other human studies i promise, this was the best i could do with the time that i have.