You ommitted the bodys main fuel source, glycogen stored in muscles.
You get fat......if you consume more calories than what you requires.
Always
At a micro time level, and at a macro one.
In-out=accumulation. Its an energy balance.
Despite what many want to believe, it doesnt matter what it is you eat.
No magic, just math.
Some foods are more efficienty converted to stored fuel
Some are less
Some are better as instant fuel for performance as they are absorbed
Some fuel sources may be better suited to different activity
That doesnt change fact. Just makes it fuzzy for some to think about. Those are performance issues. Body can convert fat stores slower than demand, you hit the wall. Barely able to walk.
Look at big picture
Energy balance still controls
Body is constantly storing energy and drawing on stores
24 hrs, 7 days
It has to, its a law of nature, Energy is neither created nor destroyed, it just changes forms.
A lttle cardio per day to keep metabolism high, dont consume more cal than needed, and you can eat anything you want, when you want, and have low body fat. Restraint is the key, which most have none.
Hikers burning 4500 cal per day dont get fat