You've heard about them doing it to models and celebrities, and now ordinary people are doing it too. The Photoshop diet is the digital manipulation of photos to make the body look slimmer or in some cases fatter.
Look up "Photoshop fat to thin" on YouTube and countless emails pop up in the style of the Dove evolution adds. As calorielab points out, they show the transition from before to after, mostly on women, but as the video above show, on male models too.
Most of these videos are pretty extreme, and mostly done just for fun. Worth1000.com, a website known to host extremely creative Photoshop contests, has hosted extreme digital makeover competitions like slim celebrities turned obese and other celebrities made anorexic, complete with bobble heads. Examples from both can be seen in the gallery.