This is one of the earliest tricks of the paper. In the initial discussion they cite numerous authors on why low glucose, i.e. hypoglycemia, affects cognition. I have seen many hypoglycemic diabetics in bad trouble from this. However, the author then silently moves on to asserting that lower levels within the normal glucose range also have this effect, but without any supporting evidence.
In addition, the commonly stated myth that people "feel hypoglycemic" could be easily disproved in 99% of people if it was worth the time and effort to do so. The awareness of hunger, awareness of time since last meal, and the nocebo suggestion that such a thing as hypoglycemia in (most) normal people exists. It is a real thing with some medical problems, and a very few otherwise healthy people, but far overstated.
If we're into anecdotal levels of evidence, I eat once a day, and _feel_ the least energetic after eating, for 30-60 minutes.
We’ll sure, food coma is a thing. But at least my own anecdote is that sipping a sugary drink helps my focus and attention last longer. I haven’t done a formal double blind study but it is something I noticed after the fact—coffee doesn’t really work for me, but a sugary, milky coffe does. I found this by doing regression on a spreadsheet of my intake for a few months and self reported energy and focus levels.
It was after he fact that I found out this a commonly reported correlation. I wouldn’t be so quick to discount it as placebo.
I know from diets that low calorie intake does affect the mind, usually in a positive manner. That's not necessarily something I would call "hypoglycemia" though. I never checked, so far.
Both glucose and insulin levels vary throughout the day, even in healthy people, so I don't see why blood sugar can't be "low", at least with respect to the individual's daily range.
In addition, the commonly stated myth that people "feel hypoglycemic" could be easily disproved in 99% of people if it was worth the time and effort to do so. The awareness of hunger, awareness of time since last meal, and the nocebo suggestion that such a thing as hypoglycemia in (most) normal people exists. It is a real thing with some medical problems, and a very few otherwise healthy people, but far overstated.
If we're into anecdotal levels of evidence, I eat once a day, and _feel_ the least energetic after eating, for 30-60 minutes.