at http://itsthewooo.blogspot.com/2011/11/response-to-does-high-circulating.html she references/states
First thing you need, is access to ad lib calories. Obesity cannot occur during food restriction. Second thing you need, is the genetic potential for your fat cells to rapidly, and powerfully, respond to insulin with fat gain. Third thing you will need is excessive insulin production.
I think this is an incomplete statement. We also require a desire to eat. We may have a bit of influence over that. That is where reward/addiction/appetite stimulation/habit/social pressure/life pressures/emotional stress/stress any source/ etc really play a role.
On another post she said:
A far better, more illuminating clinical example of the pure biological actions of insulin would be an otherwise normal subject who happens to unfortunately develop a pancreatic neoplasm, with constant on switch of insulin. And as we can see, these individuals OFTEN become fat, sometimes extraordinarily fat, and they also interestingly enough develop resistance to the actions of insulin. When the disorder starts, they are chronically hypoglycemic, but it is not unheard of for them to progress into total resistance to insulin and diabetes. Sounds like a lot of fat people I know.
Now that sounds like me, always hungry.