title: Effect of olanzapine on body composition and energy expenditure in adults with first-episode psychosis.
abstract: OBJECTIVE
  Weight gain is a commonly observed adverse effect of atypical antipsychotic medications, but associated changes in energy balance and body composition are not well defined. The authors report here the effect of olanzapine on body weight, body composition, resting energy expenditure, and substrate oxidation as well as leptin, insulin, glucose, and lipid levels in a group of outpatient volunteers with first-episode psychosis.
  
  
  METHODS
  Nine adults (six men and three women) experiencing their first psychotic episode who had no previous history of antipsychotic drug therapy began a regimen of olanzapine and were studied within 7 weeks and approximately 12 weeks after olanzapine initiation.
  
  
  RESULTS
  After approximately 12 weeks of olanzapine therapy, the median increase in body weight was 4.7 kg, a significant increase of 7.3% from first observation. Body fat, measured by dual-energy x-ray absorptiometry, increased significantly, with a propensity for central fat deposition. Lean body mass and bone mineral content did not change. Resting energy expenditure, measured by indirect calorimetry, did not change. Respiratory quotient significantly increased 0.12 with olanzapine and was greatest in those who gained >5% of their initial weight. Fasting insulin, C-peptide, and triglyceride levels significantly increased, but there were no changes in glucose levels; total, high density lipoprotein, or low density lipoprotein cholesterol levels; or leptin levels.
  
  
  CONCLUSIONS
  Olanzapine appears to have induced an increase in central body fat deposition, insulin, and triglyceride levels, suggesting the possible development of insulin resistance. The decrease in fat oxidation may be secondary or predispose patients to olanzapine-induced weight gain.
authors.affiliation: Department of Psychiatry, University of North Carolina at Chapel Hill, 27599, USA.
authors.forename: Karen A
authors.initials: KA
authors.lastname: Graham
authors.forename: Diana O
authors.initials: DO
authors.lastname: Perkins
authors.forename: Lloyd J
authors.initials: LJ
authors.lastname: Edwards
authors.forename: Robert C
authors.initials: RC
authors.lastname: Barrier
authors.forename: Jeffrey A
authors.initials: JA
authors.lastname: Lieberman
authors.forename: Joyce B
authors.initials: JB
authors.lastname: Harp
mesh_terms: D000273:Adipose Tissue / Q000187:drug effects / Q000378:metabolism; D000328:Adult; D014150:Antipsychotic Agents / Q000494:pharmacology* / Q000627:therapeutic use*; D001569:Benzodiazepines / Q000009:adverse effects / Q000494:pharmacology* / Q000627:therapeutic use*; D001823:Body Composition / Q000187:drug effects*; D001835:Body Weight / Q000187:drug effects*; D002096:C-Peptide / Q000097:blood; D004734:Energy Metabolism / Q000187:drug effects*; D005260:Female; D006801:Humans; D007328:Insulin / Q000097:blood; D008297:Male; D009765:Obesity / Q000139:chemically induced; D000077152:Olanzapine; D010084:Oxidation-Reduction / Q000187:drug effects; D011618:Psychotic Disorders / Q000188:drug therapy* / Q000378:metabolism / Q000523:psychology; D012143:Respiratory Physiological Phenomena / Q000187:drug effects; D012559:Schizophrenia / Q000188:drug therapy / Q000378:metabolism; D014280:Triglycerides / Q000097:blood
chemical_list: D014150:Antipsychotic Agents; D002096:C-Peptide; D007328:Insulin; D014280:Triglycerides; D001569:Benzodiazepines; D000077152:Olanzapine