Wait, why is sugar bad but apple juice okay?

It’s not, it’s the same bad. Pediatricians try to drill this into parents.

Agreed. (And for some of us, whole apples also have too much sugar--as do most other fruits with whole raspberries and passionfruit being exceptions, and pureeing the raspberries or incorporating them into a smoothie is just as bad as juicing them.)

Unless you're diabetic I really don't understand how an apple could have too much sugar in it.

Most advice says to avoid sugar, but the sugar in fruit is OK (the advices goes) because the fiber in the fruit slows down the absorption of the sugar. Well, my experience has been that the sugar in fruit is not OK (even if the fruit has not been juiced or pureed or processed in any way). It is quite harmful to me, the largest harm being cognitive decline (Alzheimer's or such, I have yet to get a diagnosis). I have managed to stop and partially reverse my cognitive decline by only ever eating small quantities of carbs. A whole apple in one sittings is too much! (Some apples, such as the Granny Smith variety, have less than half the carbs of an average variety, but even a Granny Smith probably has too much for me to eat a whole apple in one sitting unless I'm doing a lot of physical labor that day, which is rare. It would be OK for me to cut up a Granny Smith and freeze the pieces and eat one fifth of an apple per meal, but I haven't bothered.)

Fructose seems to be the worst carb for me, but I also limit the other carbs (glucose and starch) and one of my guesses as to why I need to do that is that if I eat more than about 12 to 20 g of carbs in any meal, a decent amount gets converted into fructose (e.g., by my liver). I believe that if I had more muscle mass, I could get away with eating more carbs (because my muscles would convert much of the glucose in my bloodstream to glycogen before my body could convert it to fructose) but it is hard for people my age to increase their muscle mass much.

Note that I assiduously avoided refined sugar (e.g., molasses or monk fruit extract or any other refined sugar, by itself or added to processed foods) during the decades during which my cognitive decline was progessing, and that is was only after I started also avoiding fruits and honey (except for a few low-sugar fruits, which in my case are frozen raspberries and frozen passionfruit) and vegetables high in carbs (like winter squash, carrot juice and more than one or two carrots per meal) that I stopped and partially reversed my cognitive decline.

I suspect that I'm far from the only one whose cognitive decline was caused by excessive consumption of carbs because of things I've read, e.g., https://news.cuanschutz.edu/news-stories/study-suggests-fruc...

(People who advise avoiding carbs often extol the benefits of ketosis. I tried ketosis, but do not like it. I've seen things that say spending too much time in the ketotic state can damage the heart, and my heart starts doing funny things when I spend too much time in ketosis, so I eat enough carbs every day to avoid ketosis, which is not much carbs.)

> Most advice says to avoid sugar

Weird advice considering your body literally turns food into sugar anyway. I suspect folks saying that sort of thing are quacks or using sugar as a scapegoat for excess calories.

placebos work

It's the familiar "natural = good, not natural = bad" fallacy. Where "natural" is defined according to the whims of each person.

I'll answer for me and not try to answer for people in general. People's metabolisms are different, different food works for them.

Empirical answer: different sensation basically the minute it enters my body, from refined sugar. I don't enjoy that feeling it and I could feel it in a blind test. My body and brain do not feel good on such sugars, and avoiding them entirely is a good way to remove the craving for them.

Scientific answer: fruit sugars are slower to take up than refined sugars, when delivered in as juice or in fruit.