This seems like an out-of-the-blue type question and granted, it just may be. But, it is worth bringing up as some people probably have countless piercings on their body or at least enough to warrant intrigue. Really, as long as you are not carrying metal that eclipses pounds (just staying in ounces) then it should not ever be an issue. At the worst, though, it may affect the reading by one or two pounds. However, unless you are obsessed with every pound possible, this will also not become an issue for you.