title: Threshold for improvement in insulin sensitivity with adolescent weight loss.
abstract: OBJECTIVE
  To assess the association of weight loss and insulin sensitivity, glucose tolerance, and metabolic syndrome (MS) in obese adolescents following weight loss treatment, and to determine the threshold amount of weight loss required to observe improvements in these measures.
  
  
  METHODS
  A randomized, controlled behavioral weight loss trial was conducted with 113 obese adolescents. Changes in fasting insulin, homeostasis model assessment of insulin resistance, whole body insulin sensitivity index (WBISI), body mass index (BMI), and MS criteria were assessed at baseline and at month 4.
  
  
  RESULTS
  There was significant improvement in all measures of insulin sensitivity at month 4. Mean fasting insulin dropped from 22.3 to 16.6 μU/mL (P < .0001). Homeostasis model assessment of insulin resistance decreased significantly from 4.9 to 3.7 (P = .001) and WBISI increased significantly from 2.87 to 3.98 (P < .0001). An 8% reduction in BMI led to a significant improvement in WBISI (P = .03) and was the optimal threshold. Fewer individuals met criteria for MS after weight loss (P = .0038), although there were no significant changes in the individual features of the syndrome.
  
  
  CONCLUSIONS
  In this trial, weight loss at month 4 was associated with improved insulin sensitivity in obese adolescents. An approximate decrease in BMI of 8% was the threshold level at which insulin sensitivity improved. As more weight loss programs are designed for obese adolescents, it will be important to have reasonable weight loss goals that will yield improvements in metabolic and cardiovascular disease risk factors.
authors.affiliation: Division of Endocrinology and Diabetes, Department of Pediatrics, The Children's Hospital of Philadelphia, Philadelphia, PA 19104, USA. abramsp@email.chop.edu
authors.forename: Pamela
authors.initials: P
authors.lastname: Abrams
authors.forename: Lorraine E
authors.initials: LE
authors.lastname: Levitt Katz
authors.forename: Reneé H
authors.initials: RH
authors.lastname: Moore
authors.forename: Melissa S
authors.initials: MS
authors.lastname: Xanthopoulos
authors.forename: Chanelle T
authors.initials: CT
authors.lastname: Bishop-Gilyard
authors.forename: Thomas A
authors.initials: TA
authors.lastname: Wadden
authors.forename: Robert I
authors.initials: RI
authors.lastname: Berkowitz
mesh_terms: D000293:Adolescent; D015415:Biomarkers / Q000097:blood; D015992:Body Mass Index; D005260:Female; D018149:Glucose Intolerance / Q000097:blood / Q000209:etiology / Q000628:therapy; D005951:Glucose Tolerance Test; D006801:Humans; D007328:Insulin / Q000097:blood; D007333:Insulin Resistance / Q000502:physiology*; D008297:Male; D024821:Metabolic Syndrome / Q000097:blood / Q000209:etiology / Q000628:therapy; D009765:Obesity / Q000097:blood / Q000150:complications / Q000628:therapy*; D016896:Treatment Outcome; D015431:Weight Loss / Q000502:physiology*; D061217:Weight Reduction Programs
chemical_list: D015415:Biomarkers; D007328:Insulin
keywords: BMI; Body mass index; CD; Conventional diet; HDL; HOMA-IR; High-density lipoprotein; Homeostasis model assessment of insulin resistance; MS; Metabolic syndrome; OGTT; Oral glucose tolerance test; WBISI; Whole body insulin sensitivity index