I once did some casual imaging for a new magazine targeted at the rapidly emerging hip Asian British middle classes. The worker next me was assiduously transforming a caucasian model into an asian one. Apparently, there were simply not enough Asian models available due to cultural and religious traditions which are not in sympathy with the requirements of the glamour industry. So Photoshop was used to alter the hue and darkness of the skin tone, neatly undermining petty cultural barriers to exploitation and profit, and possibly even altering those cultural norms by exposure.
The manipulation of images for commercial purposes is nothing new, and neither is the industrial exploitation of women. Photoshop makes the process easier and cheaper than ever, and is used for all kinds of remedial work which once would have been done in the darkroom or on the lightbox or layout table. So the boundaries of manipulation are very blurred. The entire mood of a landscape can be altered by darkening the sky, as many film photographers used to do. So my guess is that any legislation to discourage the promotion of fascistic body ideals will end up entangled in miles of legalistic wrangling.
Far better to legislate that all images in which the dimensions of any part of the model have been altered should be credited as an Artwork rather than a photograph.
Better still to tax all pornographic, degrading images of women off our streets and screens entirely. But that's apparently a gross abuse of the human rights of the advertising industry to make fortunes from the humiliation and abuse of many. And they're generally prepared to go to the european Court of Human Rights to prove it. As they did when Sweden banned junk food ads on children's TV.