title: Weekly changes in basal metabolic rate with eight weeks of overfeeding.
abstract: OBJECTIVE
  The contribution of basal metabolic rate (BMR) to weight gain susceptibility has long been debated. We wanted to examine whether BMR changes in a linear fashion with overfeeding. Our hypothesis was that BMR does not increase linearly with 1000-kcal/d overfeeding in lean healthy subjects over 8 weeks. The null hypothesis states that BMR increases linearly with 1000-kcal/d overfeeding in lean healthy subjects.
  
  
  METHODS
  Initially, 16 lean healthy sedentary subjects completed 2 weeks of weight maintenance feeding at the General Clinical Research Center. The subjects were then overfed by 1000 kcal/d over 8 weeks. BMR was measured under standard conditions each week using indirect calorimetry.
  
  
  RESULTS
  Baseline BMR was 1693 +/- 154.5 kcal/d. BMR increased from 1711 +/- 201.3 kcal/d at week 1 of overfeeding to 1781 +/- 171.65 kcal/d at the second week of overfeeding (p = 0.05). BMR fell during the third week of overfeeding to 1729 +/- 179.5 kcal/d (p = 0.05). After 5 weeks of overfeeding, BMR reached a plateau. Thereafter, there was no further change. Comparison of BMR with weeks of overfeeding was significantly different compared with the linear model (p < 0.05).
  
  
  CONCLUSIONS
  Increases in BMR in lean sedentary healthy subjects with 1000-kcal/d overfeeding are not linear over 8 weeks. There seems to be a short-term increase in BMR in the first 2 weeks of overfeeding that is not representative of longer-term changes.
authors.affiliation: Endocrine Research Unit, Mayo Clinic, Rochester, MN 55905, USA.
authors.forename: Ann M
authors.initials: AM
authors.lastname: Harris
authors.forename: Michael D
authors.initials: MD
authors.lastname: Jensen
authors.forename: James A
authors.initials: JA
authors.lastname: Levine
mesh_terms: D050154:Adiposity; D000328:Adult; D001481:Basal Metabolism / Q000502:physiology*; D050218:Body Fat Distribution; D015992:Body Mass Index; D001835:Body Weight; D002153:Calorimetry, Indirect / Q000379:methods; D005247:Feeding Behavior / Q000502:physiology*; D005260:Female; D006801:Humans; D008297:Male; D044343:Overnutrition / Q000378:metabolism*