Density of Body Fat

[jacquilynne]

This seems like it should have been googleable, but all I kept getting was sites to calculate BMI and such, which didn't seem to have the information I actually needed. The density of water (assuming certain standards, etc) is 1kg/liter. I'd like to know similarly what the density of body fat is likely to be, or if it varies too much to say specifically.

[Blake]

The term you need to search for is "specific gravity".

The density of subcutaneous and internal fat of five human subjects examined (3 males and 2 females) at 37°C was 900.0±1.03 kg/m3 and 900.0±5.1 kg/m3, respectively....It is interesting to note that the above findings indicated a mean density of 916.7 at 15°C for human fat or a specific gravity of 917.5, very close to the old value of 917.9 obtained in 1906.

Densities of subcutaneous and internal fat of the dog were almost identical to those for the man, and subcutaneous fat of the steer, pig, and lamb were also very similar. But internal fat in these three species was consistently more dense: steer 907.6, pig 904.4, lamb 921.7, at 37°C. No significant differences were found
between subcutaneous and internal fat of the rat, rabbit, and guinea pig, but the densities of these fats were higher than human fat, ranging from 902.9 to 904.6 at 37°C. The density of butter was like that of steer internal fat. The modulus of thermal expansion from measurements at 25°C and 37°C ranged from 0.84 to 1.76 m3/kg/°C.

Fidanza, F. 2003 "Body fat in adult man: semicentenary of fat density and skinfolds" Acta Diabetol 40 242–245