Does the underlined mean "covering any one part like arms, legs, etc has the same effect as covering other parts"? I don't get it.
ex) It is said that a cozy hat is a must on a cold winter’s day. We are often led to believe that most of our body heat is lost through our heads. Closer inspection of heat loss in the hatless, however, reveals that is nonsense. The myth has arisen through a flawed interpretation of an experiment in the 1950s. In the study, volunteers were dressed in Arctic survival suits and exposed to bitterly cold conditions. Because the head was the only part of their bodies left uncovered, most of their heat was lost through their heads. In fact, covering one part of the body has as much effect as covering any other. If the experiment had been performed with people wearing only swimming trunks, they would have lost no more than 10% of their body heat through their heads.
[AmE - not a teacher]
I'm confused by your confusion. You've basically repeated the phrase:
covering .......one part of the body ..........has as much effect as covering any other.
"covering any one part like arms, legs, etc has the same effect as covering ......other parts"?
But, to answer your question, yes, it's saying that there is nothing special about the head with regards to heat loss.