> Gastric bypass is really a very low calorie diet, enforced by surgery. In the very low calorie cases, the body necessarily has much less carbohydrate than a normal calorie variant; the body is in a state of semi-starvation, and that's exactly when gluconeogenesis and fat burning both ramp up.
I think you would need to address the finding that gastric bypass essentially reverses diabetes immediately after surgery. Insulin dependent diabetics end up not needing insulin immediately after surgery. The mechanism of this is described in the coursework provided by Coursera and the University of Copenhagen.
https://www.coursera.org/learn/diabetes-essential-facts
Sorry, I don't remember which lecture exactly, but it's around the one about incretins.
If you take the courses, you'll have a thorough understanding of the various ways in which insulin resistance arises. It is merely a symptom with many different mechanisms leading to the same symptom.