> promoting the absorption of, especially, glucose from the blood into fat, liver and skeletal muscle cells
> in the tissues that can carry out these reactions, glycogen and fat synthesis from glucose are stimulated
> The breakdown of triglycerides by adipose tissue into free fatty acids and glycerol is also inhibited
> Increased lipid synthesis – insulin forces fat cells to take in blood glucose, which is converted into triglycerides (aka fat)
> Increased esterification of fatty acids – forces adipose tissue to make neutral fats (i.e., triglycerides) from fatty acids
> Decreased lipolysis – forces reduction in conversion of fat cell lipid stores into blood fatty acids and glycerol
Kcals in kcals out fails practically every overweight person over 30 I know. But they won't hear about biochemistry. Poor folks aren't even eating that much, but what they do eat sufficiently inhibits liberation of the many-months-worths of energy stores they carry around all day. Don't envy them, full of energy yet out of energy!
"As far as the laws of mathematics refer to reality, they are not certain; and as far as they are certain, they do not refer to reality." - Albert Einstein
The human body is a complex system, with hormones controlling how energy is stored and made available, and nutritional content continuously altering the levels of those hormones.
Your statements completely ignore variables such as:
Bioavailability of the calories - how much of it remains in the waste (urine/feces) or is being metabolized by gutteral bacteria, for example. These variables strongly depend on the types of calories consumed, particularly the presence of dietary fiber. Soluble fiber for example is especially effective at capturing sugars and preventing their absorption in the small intestine, resulting in flatulence after arrival in the large intestine.
Insulin levels - when insulin levels are high energy is stored as fat. Hormones like insulin also influence mood and activity levels. Obese people are generally lethargic and low-energy/low-activity individuals, regardless of what is obviously an excess of energy available. This is due to the hormonal dysfunction. Hormones can cause a person to be internally starving when they're ingesting excessive calories, simply because their hormones are signaling the fat stores to effectively steal all the energy in the blood stream.
Bioavailability of calories isn't relevant here. There literally is not enough energy in that amount of sugar. Why does it matter if 80% of the available calories is absorbed of 90%?
"Insulin levels - when insulin levels are high energy is stored as fat."
It doesn't matter where energy is stored. 100% of it could have gone to fat.
He was already eating more calories than he needed. The difference is that after changing his diet he was excreting less calories, since sugar (specifically fructose in the absence of fiber) is absorbed quickly and almost entirely.
He didn't just increase his concentration of fat, he straight up gained 8.5 kilograms of mass.