title: Validity of the leg-to-leg bioimpedance to estimate changes in body fat during weight loss and regain in overweight women: a comparison with multi-compartment models.
abstract: OBJECTIVE
  To investigate changes in body composition and the validity of the leg-to-leg bioimpedance (LTL) method to measure body fat during active weight loss (WL) and weight regain (WR).
  
  
  METHODS
  Longitudinal, 12-week weight loss intervention (3.3-3.8 MJ/day) and subsequent follow-up at 1 year.
  
  
  METHODS
  Fifty-eight adult women aged between 24 and 65 years (mean age: 46.8+/-8.9 years) and with a body mass index (BMI) > or =25 kg/m(2) (mean BMI: 31.6+/-2.5 kg/m(2), range=26.0-48.2 kg/m(2)) participated in the study.
  
  
  METHODS
  Fat mass (FM) was measured at baseline, 12 weeks, 24 weeks and 52 weeks using three- and four-compartment (4-C) models, air displacement plethysmography (ADP), deuterium dilution - total body water (TBW), dual-energy X-ray absorptiometry (DXA), skinfold thickness (SFT), tetrapolar bioelectrical impedance analysis (T-BIA) and LTL.
  
  
  RESULTS
  At the end of the weight loss programme, subjects lost 9.9+/-3.5 kg weight (P<0.001) and 7.6+/-0.5 kg fat (P<0.001) but after 1 year they had regained 4.9+/-3.7 kg of weight and 3.7+/-2.9 kg of fat. The 4-C model showed that FM and TBW accounted for 76.2 and 23.6% of the loss in body mass and 81.8 and 17.7% of the tissue accrued during weight regain, respectively. The estimate of body fat change by LTL relative to multi-compartment models (WL(bias+/-2s.d.)=0.51+/-3.26 kg; WR(bias+/-2s.d.)=-0.25+/-2.30 kg) was similar to ADP, DXA and TBW in both phases but it was better than T-BIA (WL(bias+/-2s.d.)=0.17+/-7.90 kg; WR(bias+/-2s.d.)=-0.29+/-7.59 kg) and skinfold thickness (WL(bias+/-2s.d.)=2.68+/-6.68 kg; WR(bias+/-2s.d.)=-0.84+/-3.80 kg).
  
  
  CONCLUSIONS
  Weight loss and regain were associated with minimal changes in lean tissue as measured using multi-compartment models. The LTL system is a useful method to measure body composition changes during clinical weight management programmes.
authors.affiliation: MRC Human Nutrition Research, Elsie Widdowson Laboratory, Fulbourn, Cambridge, UK. susan.jebb@mrc-hnr.cam.ac.uk
authors.forename: S A
authors.initials: SA
authors.lastname: Jebb
authors.forename: M
authors.initials: M
authors.lastname: Siervo
authors.forename: P R
authors.initials: PR
authors.lastname: Murgatroyd
authors.forename: S
authors.initials: S
authors.lastname: Evans
authors.forename: G
authors.initials: G
authors.lastname: Frühbeck
authors.forename: A M
authors.initials: AM
authors.lastname: Prentice
mesh_terms: D000273:Adipose Tissue / Q000502:physiology*; D000328:Adult; D000368:Aged; D001823:Body Composition / Q000502:physiology*; D015992:Body Mass Index; D004038:Diet, Reducing; D017097:Electric Impedance; D005260:Female; D006801:Humans; D008137:Longitudinal Studies; D008875:Middle Aged; D008954:Models, Biological; D015203:Reproducibility of Results; D015430:Weight Gain / Q000502:physiology*; D015431:Weight Loss / Q000502:physiology*