Hmm it’s odd. They did feed them chow, but the chow diet was significantly fewer calories than the HCHF or LCHF diets so it can’t really be compared with them. In fact they didn’t control for calorie intake so for all it’s known the higher calorie consumption of HCHF could be the cause.

According to the results section they also did not evaluate the hyperthalmic microglial activities of the Chow (HCLF) diet so it’s unknown from the paper if If the high carb only diet had detrimental results.

Wish I could ask the authors about these holes.

I agree with your concerns. I am also concerned that the chow diet (HCLF) does not provide the same type of carbs (wheat and corn) as the other diets tested (sucrose or starch).