I doubt that. Maybe that's the average range of what's considered "healthy," but no way can it be the actual average. I'm only slightly overweight -- and look downright fit by American standards -- and my body fat is somewhere in the low 30s. If I got down to 20%, I'd be one of the leanest-looking adults I know.
I dont know what measurements you had, but
many body fat measurement methods are prone to high errors:
Body Calipers
Body calipers are used to measure skinfold thickness at various sites to estimate body fat percentages. Because the degree of error is potentially high, this method of fat measurement is just about useless if not in the hands of an expert-–and that means someone with a lot of practice and validation in order to judge the correct places on the body and the right amount of skinfold to capture. A quality pair of medical calipers is a good start.
Bioelectrical Impedance Analysis (BIA)
BIA uses a small electronic pulse that passes through muscle and fat at different rates. However, its measurements may be thrown off by how hydrated you are and how much you've eaten; it may be too inaccurate for anything other than comparative use. Users are encouraged to establish a baseline measurement and repeat measurements under consistent conditions over time to detect changes. Tanita is a popular brand.
DEXA Scanning
DEXA stands for dual energy x-ray absorptiometry and is sometimes simply called DXA. DEXA is most often used to measure bone density and lean mass, but it can also deliver fat mass readings. The system uses a body scanner, and the process can take about 15 minutes and cost upward of $100 depending on where you live and the availability and use of such technology. It appears to be quite accurate within about a 3 percent error.
Water Weighing
Essentially this entails dunking you completely underwater while you sit on scales and expel all air from the lungs. The technology is based on the displacement of water and the different density of fat and lean muscle mass. This is also an accurate method, although mainly restricted to academic and research establishments because of the enveloping nature of the procedure.
The Bod Pod
This device has been around for about 10 years and may be the best of all. The
Bod Pod is an egg-shaped cocoon within which you are enclosed for about 5 minutes. It works on the same principle as water weighing except you displace air instead of water. It's called "plethysmography". No mess, no fears of drowning. It is reported to have an accuracy of 2 percent.
So you may not have as high a body fat as you think.