Meta & Children's Online SafetyMeta terminology
NAC
Negative Appearance Comparison
The measured harm of comparing one's appearance unfavourably with what one sees on the platform. Content is scored for it, so internal documents speak of "high-NAC" content and of NAC prevalence rising with time spent.
Sources
Internal documentUnsealed internal messages ("these appearance comparisons are made much more frequently on IG vs competitors (including FB)")
Internal documentUnsealed internal messages ("Teen Well-being Communities 11/8 check-in")
Internal documentInstagram Appearance Comparison Decision - A/C PrivUndated