Will a body wave alter my natural color?

I haven't had a perm in fifteen years, but am considering a body wave
now in order to add volume to my very fine, rather thinish, shoulder
length hair. The problem I had with perms in the past is that they, when
combined with exposure to the sun, MARKEDLY altered the natural color
of my hair. It went from very dark brown to a brassy, orangy red in one
summer. This color does not go at all well with my olive skin tone. My
hair has always had very warm undertones. I try to avoid "getting sun"
but it doesn't seem to take much exposure to have great effect. I don't
really mind hats, but they do give me hat hair and are not always
practical. So, my questions is, have perm formulations changed enough
over the last fifteen years, that I don't have to expect the same result as
before regarding my color? I very much like the color of my hair and do
NOT want to have to color it after the perm. My current hairdresser
seems unconcerned, assuring me that the color will be only slightly
altered after the perm, if at all, but he is focusing on its immediate
effects. It's what the sun will do to my chemically altered hair that
concerns me.