The Nathan is a pair of shorts that sits above the purely casual end of the spectrum without reaching for a formal register it doesn't need. The easy fit and clean construction make them appropriate for smart-casual summer occasions as well as relaxed weekend use, giving them a range that most shorts simply don't have.
Wear them with a polo shirt and loafers for a neat summer look, or keep it simpler with a plain tee and trainers for a relaxed everyday outfit. The easy fit provides comfort throughout a long day in the warmth without the excessive volume that makes some casual shorts look sloppy.