Odds are you and almost everyone you know are in an abnormal metabolic condition that’s putting a constant stress on your body. Human normal is keto-adapted, not carb-adapted. This matters a lot because, depending on your personal genetic and physiological weak points, there’s a cascade of diseases, pathologies, that you can suffer.
Let’s go over the two states you can be in metabolically. I’m not a physiologist or biochemist, and I want to explain the basic concepts, so those of you who know the gory details be patient with my simplifications. When you eat a high carbohydrate (i.e. sugar) diet, it mimics our ancestors state in fruit and berry season. Simple sugars absorb quickly and elevate glucose, carbohydrates less quickly, but still trigger some insulin response. When insulin is elevated, that signals your organ systems, including your brain, to use the glucose first for normal metabolism. If there’s any glucose, fats, or proteins in excess, the only way your body can store that excess energy is as fat, mostly in the fat cells, although the liver and muscle cells can store some, too. The liver works away turning excess food into “triglycerides,” the transport and storage form of fat. Those get packaged into “lipoproteins” and shipped to the fat cells. The insulin also signals your fat cells to hold onto the fat they have and take up more fat from the lipoproteins. As I’ve mentioned elsewhere, if you’re eating one of the sugars like sucrose (table sugar) or high fructose corn syrup, that doesn’t generate an insulin response, but both those sources are about half glucose, so you’re still getting an insulin response. Meanwhile, the liver is going nuts converting the fructose to triglycerides, which are being transported out to the fat cells. Unless of course you’re eating so much sugar, and are sensitive enough to sugr, that the liver and transport systems don’t keep up. The fat builds up on and around your liver, resulting in Fatty Liver Disease (FLD). Any excess weight around your middle correlates very well with some amount of FLD. As I’ve mentioned before, you’re also wired to eat more when you’re eating sweet stuff, because your body think it needs to gorge on the fruits and berries until they’re gone.
If you’re eating a high carbohydrate diet all the time, your body adapts; carb-adaptation. It ramps up it’s glycogen storage.