[hammock]

>nonalcoholic fatty liver disease, decreased insulin sensitivity, type two diabetes, and metabolic syndrome

All of these ailments are typically comorbid with obesity, so saying "fat" is a shorthand way of getting at these things in a limited-space headline.

[lazyguy]

Right but you don't need to be fat to get any of them. They are just 'associated' with it. As in they are diseases that are more likely to impact fat people.

[AstralStorm]

Is there any direct evidence of causation or is someone shooting the wind again?

(There are ways to do it, but it's extremely hard and finicky math.)