research showed that higher body mass index, higher percentage of body fat, higher
central adiposity, and fat gain are associated with higher rates of hotflash reporting
(Gold et al. 2006 ; Thurston et al.2008b,2011b, 2013 ). These latterfindings are
consistent with a thermoregulatory role of body fat in hotflash reporting whereby
the insulating properties of subcutaneous fat (Anderson 1999 ) reduces the ability of
the body to dissipate body heat and thus increases hotflashes (Freedman 2005 ).
Refinement of this model in more recent research suggests that relations between
adiposity and hotflashes may vary by menopause stage, with higher adiposity
associated with more hotflashes early in the transition and fewer hotflashes later
into the postmenopause as adipose tissue becomes a woman’s primary estrogen
source (Thurston et al.2008b,2009b,2011b, 2013 ). Research on the role of adi-
posity in hotflash occurrence is currently an area of intensive investigation.
In addition to playing a role in the occurrence of hotflashes, adiposity may
impact the physiologic measurement of hotflashes. In hotflash research, BMI was
found to be inversely related to the magnitude of skin conductance rises with hot
flashes (Thurston et al.2009b,2011a). The reason for this difference is not clear but
may include subcutaneous adipose tissue modifying the density or functioning of
sweat glands (Havenith and van Middendorp 1990 ), the relative influence of body
characteristics (e.g., BMI) in heat dissipation responses (Havenith et al. 1995 ;
Buskirk et al. 1965 ), and/or differences in heat dissipation responses by physical
fitness, which typically varies by BMI (Havenith and van Middendorp 1990 ;
Armstrong and Pandolf 1988 ). Given“submaximal rises” among higher BMI
women, in some research higher BMI has been associated with lower sensitivity of
skin conductance measures using the standard 2μmho (0.61 normal vs. 0.20 obese;
Thurston et al.2009a,2011a). Importantly, most midlife women living in the USA
are overweight or obese (Flegal et al. 2010 ), and thus, thesefindings have important
implications for the validity of hotflash measures in research with sampling from
average populations of US women. For this reason, some investigators have
implemented methods to code these submaximal rises that fail to reach a 2μmho
criterion (Thurston et al.2009a,2011a; Gibson et al. 2014 ).
Thus, there appears to be important relations between adiposity and hotflashes
that vary by stage. However, further development of physiologic measures valid
across women of varying body sizes may be warranted to support further investi-
gation of adiposity–hotflash relations using these measures.
What is the“Gold Standard”Measure of Hot Flashes?
There have been several debates and controversies regarding the optimal, or“gold
standard,”measure of hotflashes. Proponents of physiologic measures point to their
utility for measuring hotflashes without relying upon self-report, which can be
influenced by psychological factors as well as adherence. Physiologic measures are
also useful in assessing hotflashes during sleep and other times that a woman
cannot provide a report. They further provide precise information on the timing of
11 Hot Flashes: Phenomenology and Measurement 245