In a video filmed at a shoot for the company's new adverts, the company joins the growing number of firms criticising unrealistic body ideals and stereotypes.
"We are controlled by the media. Whatever the media and a selected few in the media think is good, everyone is supposed to think is good," one model, who does not conform to conventional standards of male beauty, says in the video.
Dressmann's brand director Jens Bonesmo blamed Calvin Klein, and its 1990s ads featuring the honed physique of models such as Mark Wahlberg, for the way male underpants are advertised.
"What's really interesting is that there's a standard, originally from Calvin Klein, on how to make advertising for underwear. The only differences are the logo on the underwear and which of the famous models is wearing them. But they all have extremely fit, well-defined bodies with six, or eight, packs," he says in the video.
The new move in advertisement is in line with the new "dad-bod" trend set by Leonardo DiCaprio, who this summer went out sporting a beer belly and love handles.
Trond Blindheim of the Oslo School of Management thinks the new adverts will strike a chord, as Dressman's previous campaigns were disconnected from its typically rather unfashionable, unglamorous customer base.
"It was a bit pathetic before," he told Norwegian broadcaster TV2. "So far all of the Dressmann models have looked like superman."
"Right now, I am in a meeting with a lot of people, people who are fat and thin, tall and short. That's reality, and these are the people who use the clothes."
Bonesmo hopes the new advert will give men more confidence.
"All men are perfect. We think people will drop their shoulders and let their belly out a bit. I hope people react by relaxing a bit more," he told TV2.