"Now, some people have argued that fat lowers the glycemic index of foods and should therefore be included in carb meals. But remember, the glycemic index only gives a measure of glucose response to a meal, not insulin response. And sometimes the glucose responses to a meal and the insulin responses to a meal aren't well correlated. So although you might be slowing the rate of glucose absorption into the blood by adding fat to your meals, you'll promote high blood levels of fats, carbs, and insulin. And that's a no-no!"
I’m not arguing either way, just a little food for thought.
While it is true that some foods that are high in fat can also spike insulin levels, this only applies to high II or GI foods. It is also true that a cell will not convert fat into energy if there is glucose present. But that would only be a problem if a violent insulin spike was produced.
There is also a difference between an insulin response and a violent insulin spike. A meal consisting of both protein and carbs will cause an insulin response, but that doesn’t mean a violent insulin spike will be produced.
Glucose absorbtion will already be slower if you’re eating food that is not high on the II or GI, so any additional dietary fat will not facilitate fat storage, unless pure sugar is being consumed with your high fat meal.