Fats are metabolized to glycerol that is fed into the exact same metabolic cycle as sugar to derive energy.
One can make the argument that as Americans have increased caloric intake and decreased caloric expenditure they have grown more and more obese.
On a molecular basis there is no exemption that somehow excess calories, if they are from fat or protein, cannot be converted into lipids and stored as fat by the body.
Excess calories, from whatever source, will be stored as fat by the body.
I know that’s what it says on paper.
But it doesn’t play out.
Remember, I’ve been living on meat and fat only for over 5 years. I’ve lost 60 lbs.
I conducted a experiment 3 years ago. For a solid 4 weeks, I literally gorged myself on meat and fat (and this is very hard to do!); with the totals exceeding 4,000 calories per day. I wound up within 1 lb of my starting weight.
The calories in/calories out thing doesn’t work out. Every calorie is not equivalent to every other calorie.
Simplisticly: They don’t work in a vacuum. Meat and fat do not cause the insulin response (fat storage) mechanism like sugars (carbs, included). Without that, fat storage is minimized and excess is excreted.