Body composition assessment in extreme obesity and after massive weight loss induced by gastric bypass surgery.
Body composition methods were examined in 20 women [body mass index (BMI) 48.7 +/- 8.8 kg/m(2)] before and after weight loss [-44.8 +/- 14.6 (SD) kg] after gastric bypass (GBP) surgery. The reference method, a three-compartment (3C) model using body density by air displacement plethysmography and total body water (TBW) by H(2)18O dilution (3C-H(2)18O), showed a decrease in percent body fat (%BF) from 51.4 to 34.6%. Fat-free mass hydration was significantly higher than the reference value (0.738) in extreme obesity (0.756; P < 0.001) but not after weight reduction (0.747; P = 0.16). %BF by H(2)18O dilution and air displacement plethysmography differed significantly from %BF by 3C-H(2)18O in extreme obesity (P < 0.05) and 3C models using (2)H(2)O or bioelectrical impedance analysis (BIA) to determine TBW improved mean %BF estimates over most other methods at both time points. BIA results varied with the equation used, but BIA better predicted %BF than did BMI at both time points. All methods except BIA using the Segal equation were comparable to the reference method for determining changes over time. A simple 3C model utilizing air displacement plethysmography and BIA is useful for clinical evaluation in this population.
Das
Sai Krupa
SK
Jean Mayer USDA Human Nutrition Research Center on Aging at Tufts University, Boston 02111, USA.
Roberts
Susan B
SB
Kehayias
Joseph J
JJ
Wang
Jack
J
Hsu
L K George
LK
Shikora
Scott A
SA
Saltzman
Edward
E
McCrory
Megan A
MA
D000273:Adipose Tissue / Q000502:physiology; D000368:Aged; D001823:Body Composition / Q000502:physiology*; D001827:Body Height / Q000502:physiology; D001835:Body Weight / Q000502:physiology; D003720:Densitometry; D017097:Electric Impedance; D005260:Female; D015390:Gastric Bypass; D006801:Humans; D008875:Middle Aged; D008954:Models, Biological; D009767:Obesity, Morbid / Q000473:pathology* / Q000628:therapy; D011865:Radioisotope Dilution Technique; D015431:Weight Loss / Q000502:physiology*