Someone who goes to the gym but doesn't use the equipment. The average gym nerd continually talks about form and caloric intake. Being a gym nerd is often accompanied by a PT certification.
Me:"If u used ur hours from playing roblox to going to the gym you'd be ripped asf"
10 year old on roblox:"YoUr SUcH a GyM nErD yOu ShOuLdN't Be FoRcInG PeOpLe" blah blah blah.