What is the name of the medical condition that affects African
American women that stipulates there are more fat deposits in the
hips, thighs and buttocks? This can also be linked  to higher rates of
diabetes, hypertension, etc. (related topics include, adiposity,
BMI/body mass index). I believe the word begins with an 's' and ends
in 'ia'?

I believe the word you're looking for is "steatopygia."

"Buttock size also shows moderate population-specificity, being fairly
small among East Asian populations and larger among European and
African populations. Among the Kalahari bushwomen and the Hottentots,
female buttock size is particularly exaggerated into a condition known
as 'steatopygia'; this condition bears no clear relation to any
ecological requirement for fat storage."

Human Evolution
http://www.humanevolution.net/a/africanamerican.html

"steatopygia: Extreme accumulation of fat on and about the buttocks,
especially of women, as among the Hottentots, Bushmen, and certain
other South African peoples."

WebRef
http://www.webref.org/anthropology/s/steatopygia.htm 

"Many African groups have individuals with well-developed buttocks and
thighs, resembling steatopygia. These probably represent some past
interracial mixture, as the archaeological record reveals that the
Bushmen-Hottentot (Capoid) group once dominated most of Africa and
have been pinched into a relic area, replaced by more dominant
groups."

Linda Mealey's Home Page
http://employees.csbsju.edu/lmealey/hotspots/Chapter12.htm

Google search strategy:

Google Web Search: "steatopygia"
://www.google.com/search?hl=en&ie=UTF-8&q=steatopygia

I hope this is the word you were seeking. If it is not, please request
clarification, and I'll resume the quest.

Best regards,
pinkfreud

Thank you very much for the five-star rating and the generous tip!

~pinkfreud