Discriminating between body fat and fluid changes in the obese adult using bioimpedance vector analysis

A. Piccoli, A. Brunani, G. Savia, L. Pillon, E. Favaro, M. E. Berselli, F. Cavagnini

Research output: Contribution to journalArticlepeer-review


OBJECTIVE: Conventional body composition methods may produce biased quantification of fat and fat-free mass in obese subjects, due to possible violation of the assumption of constant (73%) tissue hydration. We used an assumption-free, graphical method for interpreting body weight variation in obesity using bioelectrical measurements. DESIGN: 540 obese subjects with body mass index (BMI) > 31 kg/m2 without apparent edema were compared to 726 healthy subjects with BMI <31 kg/m2 and to 50 renal patients with apparent edema. A subgroup of 48 obese subjects were evaluated again after weight loss (8.6 kg, 3 BMI units) following one-month energy restriction (5 MJ/d, 1200 kcal/d). 32 obese uremic patients were evaluated before and after a dialysis session (3.2 kg fluid removed). Direct measurements obtained from standard 50 kHz frequency bioelectrical impedance analyzer were used as impedance vectors in the Resistance-Reactance Graph. RESULTS: 1) Impedance vectors of obese subjects could be discriminated from those of edematous patients with 91% correct allocation; 2) A significant lengthening of vectors was observed after fluid loss of 3 kg in obese subjects; but 3) A body weight loss of about 9 kg after energy restriction was associated with no vector displacement. CONCLUSION: A different impedance vector pattern was associated with body weight loss in obesity due to fluid removal (vector lengthening) versus an energy-restricted diet (no vector displacement).

Original languageEnglish
Pages (from-to)97-104
Number of pages8
JournalInternational Journal of Obesity
Issue number2
Publication statusPublished - 1998


  • Bioelectrical impedance
  • Edema
  • Energy restriction
  • Hemodialysis
  • Obesity
  • Weight loss

ASJC Scopus subject areas

  • Food Science
  • Endocrinology
  • Medicine (miscellaneous)
  • Endocrinology, Diabetes and Metabolism
  • Public Health, Environmental and Occupational Health


Dive into the research topics of 'Discriminating between body fat and fluid changes in the obese adult using bioimpedance vector analysis'. Together they form a unique fingerprint.

Cite this