Basically it's a way of saying "the most these can measure is a body fat percentage of 49%, if you're at 50% body fat or above ask for a trainer" They're not saying "if your body fat percentage is over 25 ask a professional" they're saying "if 50% of you is just a coat of fat maybe don't worry about body fat percentages right now, just eat like a person for years and come back and ask again." Edit: I probably should have explained that it's a table for caliper measurements.  You pinch your fat in 3 specific parts of your body (can be more, but this table is for 3), and you use those measurements to work out your estimated body fat percentage. You normally want someone else to be pinching and measuring for you so you don't twist your body in funny ways and get false measurements. If you add those up, you can look at a chart like this one and estimate your body fat percentage. It's not perfect but, really, unless you pay for something like a dexa scan it's hard to get an exact number. This one talks about 188 as it's limit, 188 seems to be the number for around 48% body fat, which obviously is waaaayyyy too much.