In this paper of the WHO, it is claimed that we should limit our consumption of free sugars:
WHO recommends a reduced intake of free sugars throughout the lifecourse. [...]
Free sugars include monosaccharides and disaccharides added to foods and beverages by the manufacturer, cook or consumer, and sugars naturally present in honey, syrups, fruit juices and fruit juice concentrates.
At first, I was wondering if the sugars in a fruit can be different from sugars in a juice. According to the answer to my question here, the sugar molecules are exactly the same in both (in the case of a 100% pure juice).
So, why this recommendation? Why doesn't our body digest sugars from fresh fruit the same way as sugars from juice? To make it simple, my question only concerns 100% pure juice with no added sugars.
I tried to find an answer and, according to the answers of this question, because our body is slow to digest sugars from a fruit, it assimilates it better. Is it right? And, if it is the case, if we eat fiber and starch with our fruit juice, it should be the same as a fresh fruit, right?