Research in the United Kingdom found, "Younger men and women who read fitness and fashion magazines could be psychologically harmed by the images of perfect female and male physiques." Young women and men exercise excessively in an effort to achieve what they consider an attractively-fit and muscular body, which may lead to body dysmorphic disorder or muscle dysmorphia. Although the stereotypes may have remained constant, the value attached to masculine stereotypes has changed; it has been argued that masculinity is an unstable phenomenon, never ultimately achieved.