Sugar and motivation

I reread Are Wireheads Happy?[1], which is about the difference between liking and wanting.

I’ve noticed that too much simple carbs (not terribly much—three twenty ounce Cokes on consecutive days will do it) severely damages my desire to do much of anything, and the effects take approximately two low-simple carbs days to clear out.

This is obviously something physiological, even though it looks like an emotional problem. Failing to remember clue to avoid simple carbs (a dessert once a week might not be a problem) might be an emotional issue. Too much sugar used to lead to an internal voice saying “I don’t care”. This time, it didn’t, but if I thought of something I might do, there was a clear feeling of “no reward there” and a sense that it was too much effort. I was capable of enjoying things, but not of anticipating that I would like them.

I’m wondering if anything is known about simple carbs, motivation, and/​or serotonin/​dopamine.

[1]Recommended here.