\> Sugar is a simple carbohydrate, as opposed to complex carbohydrates (starch and fiber).
There are are three common simple sugars - glucose, fructose, and galalactose.
There are compound sugars (disaccharides) that are made up of those:
sucrose = glucose + fructose
lactose = glucose + galactose
maltose = glucose + glucose
The underlying metabolism of the simple sugars is different; glucose can be burned by many cells in the body, while fructose can only (mostly, really) be converted to glucose or fat by the liver.
\>Both types of carbs supply blood glucose, but complex carbs do it in a healthier way.
Complex carbs are mostly starches - chains of glucose - and they get broken down to glucose quickly, and therefore have the quickest impact on blood glucose. If you look at glycemic index and glycemic load, all of the highest ranking foods are starchy.
Having said that, fructose is likely more of an issue because of its link to metabolic disease.
\> It has no nutritional value at all, whether natural or added (unless you have hypoglycemia).
Sugars are not *structural* in the body; they are just used for fuel. All sugars.
\>Natural sugar is only better because it generally comes with a healthier ratio of sugar to other nutrients, while added sugar worsens that ratio.
\>It’s okay to consume in moderation. The ratio of sugar to healthier nutrients is what matters most.
Whether this is true depends on the kind of sugar, how metabolically sick you are (only 12% of US adults are metabolically healthy), and what you mean by “moderation”.