Sugar is it bad for health?

Apart from the fact that it contributes by its caloric intake to obesity, sugar is it toxic in itself as we hear?

Short answer

The toxicity of sugar, when consumed in larger amounts than necessary, is a theory of Dr. Robert Lustig, that is confirmed by experience.
Refined sugar or beverages with fructose make liver working at warp speed, prevent the body do its job of processing and eliminating sugar and induce adverse effects on the body that reduce life expectancy.

Long answer

What sugar?

The theory of Dr. Lustig denounces both fructose as glucose when in liquid form for the first and refined for the second.
Generally all sugars, consumed in pieces or in beverages.
Unlike carbohydrates of pasta for example, which can contribute to weight gain, but did not themselves have a negative effect on the body.

Refined sugar is a combination of fructose and glucose, whereas carbohydrates contain only glucose. But this one in the case is part of complex molecules that are assimilated slowly, that changes everything.

Why is sugar harmful?

Sugar is a poison. Not only because it provides calories, but for the effects it causes in the body.
Sugars, by definition, always put us in a situation of excess because the body can not eliminate them as it does for carbohydrates.
While glucose is used by all body cells for fuel, fructose is metabolized by the liver, wherever it comes from refined sugar or drinks.
And we know that the liver will tend to turn it into fat. The body can not provide enough insulin to eliminate it and becomes a machine to produce fat.

What consequences?

There is a correlation between diabetes and the consumption of refined sugar throughout the World.
Cancer is also linked to excess fat, which can be consumed directly or derived from sugar processing.

But the three main modern evils, cardiac risk, cancer and Alzheimer's are closely linked to metabolic syndrome (MetS) which is caused by resistance to insulin, so a poor metabolism of glucose.
Whether the cause of the metabolic syndrome or not, sugar is always a factor in the ills MetS causes...

How sugar can we consume per day?

It is a question that lacks an objective response, unfortunately there is no specific value to measure the excess which is based on a scientific study.
The recommended maximum daily intake in simple sugar (brown or white) are 20 g per day (we tend to consume more).

It is actually recommended to consume mostly carbohydrates and we can therefore regard sugar as a food to consume exceptionally.

If you want to put sugar in coffee, prefer brown cane sugar which contains minerals and vitamins, as opposed to white sugar. In addition, thanks to minerals, it promotes less caries.

Dr. Robert Lustig is an expert in childhood obesity in the school of medicine at the University of California. It conducts research on obesity-related disorders in 1999.