title: Variations in the size of the major omentum are primarily determined by fat cell number.
abstract: OBJECTIVE
  Accumulation of visceral adipose tissue (VAT) is strongly linked to insulin resistance. Variations in the size of any adipose depot are determined by alterations in adipocyte volume and/or number. The individual contribution of each of the latter factors was determined in the major omentum, a fully resectable VAT depot.
  
  
  METHODS
  Total removal of the major omentum (omentectomy) was performed in conjunction with bariatric surgery in 55 obese patients. Tissue weight as well as mean adipocyte size and number in the omentum were determined. In subgroups, total VAT was estimated by computerized tomography (n = 17) or dual-energy x-ray absorptiometry (n = 34).
  
  
  RESULTS
  The weight of the major omentum (on average 0.6 kg) correlated significantly with total VAT mass estimated by computerized tomography or dual-energy x-ray absorptiometry (r = 0.48-0.7; P < .01). Omental weight in relation to total body fat correlated with several features of the metabolic syndrome and inversely with serum-leptin (P < .001). Mean adipocyte size and total adipocyte number correlated strongly with omental weight (r = 0.6-0.8; P < .0001), irrespective of body mass index and total body fat mass, and accounted almost in total for interindividual variations in omental size. However, stepwise regression analysis demonstrated that adipocyte number was significantly (P < .0001) more important (62%) than adipocyte size (35%).
  
  
  CONCLUSIONS
  The size of the major omentum is representative for VAT mass and correlates with a pernicious metabolic profile. Variations in omental weight are primarily determined by adipocyte number and to a lesser degree by adipocyte size, suggesting that increased VAT mass in obesity is predominantly dependent on adipocyte proliferation.
authors.affiliation: Karolinska Institutet, Department of Medicine, Karolinska University Hospital Huddinge, SE-141 86 Stockholm, Sweden. peter.arner@ki.se
authors.forename: Peter
authors.initials: P
authors.lastname: Arner
authors.forename: Daniel Peter
authors.initials: DP
authors.lastname: Andersson
authors.forename: Anders
authors.initials: A
authors.lastname: Thörne
authors.forename: Mikael
authors.initials: M
authors.lastname: Wirén
authors.forename: Johan
authors.initials: J
authors.lastname: Hoffstedt
authors.forename: Erik
authors.initials: E
authors.lastname: Näslund
authors.forename: Anders
authors.initials: A
authors.lastname: Thorell
authors.forename: Mikael
authors.initials: M
authors.lastname: Rydén
mesh_terms: D050154:Adiposity; D000328:Adult; D050110:Bariatric Surgery; D015992:Body Mass Index; D002452:Cell Count; D048429:Cell Size; D015331:Cohort Studies; D005260:Female; D006801:Humans; D050152:Intra-Abdominal Fat / Q000000981:diagnostic imaging / Q000473:pathology*; D020738:Leptin / Q000097:blood; D008297:Male; D024821:Metabolic Syndrome / Q000150:complications; D008875:Middle Aged; D009767:Obesity, Morbid / Q000097:blood / Q000150:complications / Q000473:pathology* / Q000601:surgery; D009852:Omentum / Q000000981:diagnostic imaging / Q000473:pathology* / Q000601:surgery; D009929:Organ Size; D011859:Radiography; D050507:Subcutaneous Fat, Abdominal / Q000000981:diagnostic imaging / Q000473:pathology; D055815:Young Adult
chemical_list: D020738:Leptin