title: Effect of prolonged moderate and severe energy restriction and refeeding on plasma leptin concentrations in obese women.
abstract: BACKGROUND
  Plasma leptin in humans is subject to both long- and short-term regulation; it correlates with indexes of body fat that can only change slowly. However, short-term fasting causes large and rapid decreases.
  
  
  OBJECTIVE
  We tested the interactions between energy intake and fat loss on plasma leptin during prolonged moderate and severe energy restriction, with a view to understanding mechanisms of control.
  
  
  METHODS
  Postabsorptive leptin was measured with an enzyme-linked immunosorbent assay specific for the human peptide in 21 obese women aged 41 +/- 3 y (weight: 102 +/- 4 kg; 48 +/- 1% body fat) after 1 wk of a weight-maintaining diet and then weekly for 4 wk during a total fast (group 1); a 1.9-MJ/d all-protein, very-low-energy diet (VLED) (group 2); or a low-energy, balanced-deficit diet (BDD) providing 50% of maintenance energy (group 3). In groups 1 and 2, leptin was also measured after 1 wk of refeeding with a diet equivalent to the BDD.
  
  
  RESULTS
  Mean leptin decreased markedly by up to 66% (P < 0.001) at week 1 of energy restriction and then gradually thereafter. The change in leptin per kilogram fat mass correlated with that in glucose concentrations [r = 0.538 (P = 0.012) at week 1 and r = 0.447 (P = 0.042) at week 4] but not with that in fat mass. During refeeding postfasting, leptin increased (P = 0.008), despite an ongoing loss of fat mass and correlated positively with changes in resting energy expenditure. At times with comparable cumulative energy restriction and fat loss between diets, the percentage change in leptin paralleled that in glucose.
  
  
  CONCLUSIONS
  In obesity, changes in energy intake over days to weeks are a primary modulator of plasma leptin concentrations that are related to the change in glycemia and are able to override the regulatory influence of fat mass.
authors.affiliation: McGill Nutrition and Food Science Centre, Royal Victoria Hospital, Montréal, Canada.
authors.forename: B E
authors.initials: BE
authors.lastname: Wisse
authors.forename: L A
authors.initials: LA
authors.lastname: Campfield
authors.forename: E B
authors.initials: EB
authors.lastname: Marliss
authors.forename: J A
authors.initials: JA
authors.lastname: Morais
authors.forename: R
authors.initials: R
authors.lastname: Tenenbaum
authors.forename: R
authors.initials: R
authors.lastname: Gougeon
mesh_terms: D000328:Adult; D000704:Analysis of Variance; D004032:Diet; D002149:Energy Intake; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D006801:Humans; D020738:Leptin; D009765:Obesity / Q000097:blood*; D011506:Proteins / Q000378:metabolism*
chemical_list: D020738:Leptin; D011506:Proteins