I do not use them as a marketing tool. The ones you see in advertising are often not real (ie. photoshop, one enlarged/one smaller, etc. and a lot are of the same people from other ads.)
But I do use photos for clients that want them. I use them for posture improvement, alignment issues, etc. and sometimes as a tool for weight loss.
When I first started out, I tried to use them but came up against a lot of resistance from clients(some people don’t even like getting weighed or measured). Although they are sometimes powerful marketing tools, the client’s wishes come first in terms of what they are comfortable with. I find that clients are much more agreeable to testimonials, to the point where most of them allow their first and last names to be used(not just initials that you see all the time.)
I use them. I’ve often found that the client forgets how far they have come. I use them as a way to show how their posture has changed, as well as their weigt. As the other trainers have mentioned, I always keep the client in mind and never use the pictures for marketing without the client’s permission.
I think that if used ‘properly’ they can be a good tool. In my opinion, whatever tool speaks to a particular person and gets them motivated to engage in HEALTHY exercise is potentially useful. Since so many in our society are focused on and motivated by the cosmetic aspects of fitness, ‘before and after’ pictures can be useful. I would caution however that this ‘motivation’ needs to be tempered by the person’s trainer so that they are not solely, or even primarily, motivated by what they see in the mirror and use that as their sole or primary indicia of becoming healthier.
My two cents.