title: Effects of weight gain and weight loss on regional fat distribution.
abstract: BACKGROUND
  Normal-weight adults gain lower-body fat via adipocyte hyperplasia and upper-body subcutaneous (UBSQ) fat via adipocyte hypertrophy.
  
  
  OBJECTIVE
  We investigated whether regional fat loss mirrors fat gain and whether the loss of lower-body fat is attributed to decreased adipocyte number or size.
  
  
  METHODS
  We assessed UBSQ, lower-body, and visceral fat gains and losses in response to overfeeding and underfeeding in 23 normal-weight adults (15 men) by using dual-energy X-ray absorptiometry and abdominal computed tomography scans. Participants gained ∼5% of weight in 8 wk and lost ∼80% of gained fat in 8 wk. We measured abdominal subcutaneous and femoral adipocyte sizes and numbers after weight gain and loss.
  
  
  RESULTS
  Volunteers gained 3.1 ± 2.1 (mean ± SD) kg body fat with overfeeding and lost 2.4 ± 1.7 kg body fat with underfeeding. Although UBSQ and visceral fat gains were completely reversed after 8 wk of underfeeding, lower-body fat had not yet returned to baseline values. Abdominal and femoral adipocyte sizes, but not numbers, decreased with weight loss. Decreases in abdominal adipocyte size and UBSQ fat mass were correlated (ρ = 0.76, P = 0.001), as were decreases in femoral adipocyte size and lower-body fat (ρ = 0.49, P = 0.05).
  
  
  CONCLUSIONS
  UBSQ and visceral fat increase and decrease proportionately with a short-term weight gain and loss, whereas a gain of lower-body fat does not relate to the loss of lower-body fat. The loss of lower-body fat is attributed to a reduced fat cell size, but not number, which may result in long-term increases in fat cell numbers.
authors: Division of Cardiovascular Diseases, Mayo Clinic, Rochester, MN, USA.
authors: Prachi
authors: P
authors: Singh
authors: Virend K
authors: VK
authors: Somers
authors: Abel
authors: A
authors: Romero-Corral
authors: Fatima H
authors: FH
authors: Sert-Kuniyoshi
authors: Snigdha
authors: S
authors: Pusalavidyasagar
authors: Diane E
authors: DE
authors: Davison
authors: Michael D
authors: MD
authors: Jensen
mesh_terms: D017667:Adipocytes / Q000378:metabolism; D000328:Adult; D001823:Body Composition; D050218:Body Fat Distribution; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D050152:Intra-Abdominal Fat / Q000378:metabolism; D008137:Longitudinal Studies; D008297:Male; D050151:Subcutaneous Fat / Q000378:metabolism*; D015430:Weight Gain; D015431:Weight Loss; D055815:Young Adult