Certified personal trainers will suggest to male bodybuilders that they aim for a body fat percentage between 2–4% by contest time. However it is unclear that such levels are ever actually attained since (a) the means to measure such levels are, as noted below, lacking in principle, are inaccurate, and (b) 4-6% is generally considered a physiological minimum for human males.
From forum.bodybuilding.com:
There's also guys that get leaner than me and probably are on the verge of the high 2's if not at least in the low 3's.
From forum.bodybuilding.com:
the presumption is usually 2-3 but I heard some say it is more 4-5
People are claiming that 2-4% bodyfat percentage is attainable for bodybuilding competitions. Wikipedia expresses doubt about that claim due to lacking a means of measurement at that level and cites a paper claiming that 4-6% is the physiological limit.
What does the evidence say?