Impact of body-composition methodology on the composition of weight loss and weight gain

Eur J Clin Nutr. 2013 May;67(5):446-54. doi: 10.1038/ejcn.2013.35. Epub 2013 Feb 20.

Abstract

Background/objectives: We intended to (i) to compare the composition of weight loss and weight gain using densitometry, deuterium dilution (D₂O), dual-energy X-ray absorptiometry (DXA), magnetic resonance imaging (MRI) and the four-compartment (4C) model and (ii) to compare regional changes in fat mass (FM), fat-free mass (FFM) and skeletal muscle as assessed by DXA and MRI.

Subjects/methods: Eighty-three study participants aged between 21 and 58 years with a body mass index range of 20.2-46.8 kg/m(2) had been assessed at two different occasions with a mean follow-up between 23.5 and 43.5 months. Body-weight changes within < 3% were considered as weight stable, a gain or a loss of >3% of initial weight was considered as a significant weight change.

Results: There was a considerable bias between the body-composition data obtained by the individual methods. When compared with the 4C model, mean bias of D₂O and densitometry was explained by the erroneous assumption of a constant hydration of FFM, thus, changes in FM were underestimated by D₂O but overestimated by densitometry. Because hydration does not normalize after weight loss, all two-component models have a systematic error in weight-reduced subjects. The bias between 4C model and DXA was mainly explained by FM% at baseline, whereas FFM hydration contributed to additional 5%. As to the regional changes in body composition, DXA data had a considerable bias and, thus, cannot replace MRI.

Conclusions: To assess changes in body composition associated with weight changes, only the 4C model and MRI can be used with confidence.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Absorptiometry, Photon / methods
  • Adipose Tissue*
  • Adult
  • Bias
  • Body Composition*
  • Body Fluid Compartments*
  • Body Mass Index
  • Body Water*
  • Body Weights and Measures / methods*
  • Densitometry / methods
  • Deuterium Oxide
  • Electric Impedance
  • Female
  • Humans
  • Indicator Dilution Techniques
  • Magnetic Resonance Imaging / methods
  • Male
  • Middle Aged
  • Muscle, Skeletal
  • Obesity
  • Weight Gain*
  • Weight Loss*

Substances

  • Deuterium Oxide