I don’t think that promoting exercise as a component of healthy living makes a statement on body image. People who exercise have all types of bodies, all of which are acceptable.
It is paternalistic to “force” people to go to the gym to receive this compensation for their work. But there’s also plenty of research showing positive benefits of exercise on overall well-being for it to make sense for businesses to incentivize it from a worker performance perspective without body image entering into the discussion.