From Taubes at http://garytaubes.com/2011/11/catching-up-on-lost-time-%E2%80%93-the-ancestral-health-symposium-food-reward-palatability-insulin-signaling-and-carbohydrates%E2%80%A6-part-iid/
" This cephalic release of insulin also serves to clear the circulation of “essentially anything an animal or a person can use for fuel. Not just blood sugar, but fatty acids, as well. All those nutrients just go away.” Hence, the thought of eating makes us hungry, because the insulin secreted in response depletes the bloodstream of the fuel that the peripheral tissues and organs need to survive."
In general my idea is we need both palatable available food, reward if you like, and insulin resistance, insulin to gain weight.
When I was a young man, I worked in exploration and construction camps many winters. Most people would come in and gain 10 to 20 pounds and then get bored with the good food available. A few of us would be up 50 pounds by spring, when the job ended. When it was our nickle buying the food, it was less plentiful, and we lost weight.
To lose, the only way is to cut both hyper-palatable available food and insulin generating food.