If there is evidence I haven't seen any. Pretty much everything I have seen suggests that A) You should meet your macro needs which are slightly different for everyone, B) after that don't over eat, but what you eat doesn't really matter.

From a weight loss perspective low sugar diets are good for psychological reasons, not thermodynamic ones. Sugar tends to cause quick, but short lived fullness, where fat and protein take longer to kick in but once they do they are much longer lived.

Someone who is highly active can consume a lot more fructose-containing sugar than someone who is sedentary, and in fact fructose-containing sugar is more efficient at restoring liver glycogen than straight glucose. The problem comes when the liver's glycogen stores are full, and primary pathway for disposing of that fructose is via de-novo lipogenesis.

Like anything, the problem is consumption to excess. Unfortunately, excess in this case (for the typical sedentary person) is quite a small amount.

I don't think it's conclusive - that's my point.

I think it is conclusive that there are no old obese people.