Sugar does not cause inflammation. Sugar lowers cortisol and adrenaline levels. These stress hormones suppress existing inflammation. So in people with elevated catecholamine levels sugar intake tends to unmask damage and initiate a healing process.

This is related to the reason people think low carb diets work. Low carb dieting sends stress hormones way up, because cortisol is necessary to break down proteins into needed sugars. People tend to feel pretty good at first in this state. The problem is it totally breaks down into bad endocrine and metabolic problems after two or three years. Nobody debates that ketogenic diets seem to work for weight loss in the short run; the issue is that in the long run they're a health disaster.