title: A twin study of weight loss and metabolic efficiency.
abstract: OBJECTIVE
  To assess the genetic contribution to determinants of therapeutic weight loss in obese female identical twins.
  
  
  METHODS
  Subjects were studied for 40 days on an inpatient unit in three phases: 7 baseline days; 28 days of weight reduction by a very low calorie diet (1.6 MJ per day); and 5 days after weight reduction.
  
  
  METHODS
  Fourteen pairs of premenopausal obese female identical twins (age: 39.0+/-1.7 y; body weight (BW): 93.9+/-21.2 kg; body mass index (BMI): 34.2+/-7.8 kg/m2).
  
  
  METHODS
  : Body composition by hydrodensitometry and resting metabolic rate by indirect calorimetry were assessed before and after weight loss.
  
  
  RESULTS
  : There was great variability among pairs in loss of weight (5.9-12.4 kg) and body fat (3.1-12.4 kg). By contrast, the intraclass correlation (ICC) within twin pairs was 0.85, P<0.001 for weight and 0.88, P<0.001 for body fat. A measure of metabolic efficiency, calculated as the difference between 'estimated' and 'measured' energy deficit showed high intrapair correlation (ICC=0.77; P<0.001).
  
  
  CONCLUSIONS
  The high correlation in metabolic efficiency within twin pairs in response to therapeutic weight loss suggests a strong genetic contribution.
authors.affiliation: Obesity Unit, 3rd Department of Internal Medicine, The First Medical Faculty, Charles University, Prague, Czech Republic. vhai@lf1.cuni.cz
authors.forename: V
authors.initials: V
authors.lastname: Hainer
authors.forename: A
authors.initials: A
authors.lastname: Stunkard
authors.forename: M
authors.initials: M
authors.lastname: Kunesová
authors.forename: J
authors.initials: J
authors.lastname: Parízková
authors.forename: V
authors.initials: V
authors.lastname: Stich
authors.forename: D B
authors.initials: DB
authors.lastname: Allison
mesh_terms: D000328:Adult; D001481:Basal Metabolism / Q000235:genetics; D001823:Body Composition / Q000235:genetics*; D002153:Calorimetry, Indirect; D004038:Diet, Reducing; D004734:Energy Metabolism / Q000235:genetics*; D005260:Female; D006801:Humans; D009765:Obesity / Q000178:diet therapy / Q000235:genetics* / Q000378:metabolism; D015431:Weight Loss / Q000235:genetics*