If all carbohydrates get broken down to their most simple form, sugar, why is it unhealthy to just eat tablespoons of sugar?
In: Biology
“Sugar” is a slightly problematic term, because it is a term for a class of compounds.
Table sugar, which is normally what we have around, is sucrose, which is made up of two simple sugars stuck together. Your body has no issue splitting them up, so each molecule of sucrose becomes 1 glucose and 1 fructose.
Most sweet foods contain either sucrose directly, or “high fructose corn syrup” which, is a mixture of fructose and glucose all mixed together.
Carbs are mostly just long chains of glucose, and enzymes happily cleave off glucose from the chains and use it. So carbs become sugar, but mostly, become glucose. This is energy for the whole body, every cell.
The difference comes with fructose…. remember the sucrose is a source of it…. When your liver processes sugars, it makes fats and cholesterol. This is “de novo lipogenysis” which is just the fancy latin way of saying “the creation of new fat”.
The thing is, remember how I said glucose is food for your whole body? Because of that, only a small percentage <10% ever gets processed by the liver.
Fructose however is not an energy source for every cell. Fructose is processed in the liver, and 90% of it goes there. [Fructolysis](https://en.wikipedia.org/wiki/Fructolysis) is the process:
> Unlike glucose, which is directly metabolized widely in the body, fructose is almost entirely metabolized in the liver in humans, where it is directed toward replenishment of liver glycogen and triglyceride synthesis.[1] Under one percent of ingested fructose is directly converted to plasma triglyceride.[2] 29% – 54% of fructose is converted in liver to glucose, and about a quarter of fructose is converted to lactate. 15% – 18% is converted to glycogen.[3] Glucose and lactate are then used normally as energy to fuel cells all over the body.[2]
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