Q: I have a comment on question 38.skinfold calipers only measures the fat under the skin but the human body also has fat which is not in that area so isnt the BI method more accurate?

A: No, bioimpedance measures are notorious for poor accuracy and poor consistency. They rely on the fact that fat tissues conduct electricity much worse than tissues with water content. The problem is that water content can vary greatly in your body both in short-term (hours) and long-term (days, months, years) time scales due to any number of reasons. The main reason for the popularity of bioimpedance devices is good marketing and ease of use. Unfortunately most people don't know better and assume that BI measures are as trustworthy as weight measures and that is just not the case.

The amount of subcutaneous (under-skin) fat is roughly directly proportional to the total amount of fat in the body. So measuring subcutaneous fat with calipers and plugging the results into empirically derived equations (such as 3-point or 7-point provided on this site, as well as several others) gives you a good approximation of the total percent body fat. I definitely recommend calipers over BI for tracking BF%.