title: Metabolic response to experimental overfeeding in lean and overweight healthy volunteers.
abstract: Possible adaptive mechanisms that may defend against weight gain during periods of excessive energy intake were investigated by overfeeding six lean and three overweight young men by 50% above baseline requirements with a mixed diet for 42 d [6.2 +/- 1.9 MJ/d (mean +/- SD), or a total of 265 +/- 45 MJ]. Mean weight gain was 7.6 +/- 1.6 kg (58 +/- 18% fat). The energy cost of tissue deposition (28.7 +/- 4.4 MJ/kg) matched the theoretical cost (26.0 MJ/kg). Basal metabolic rate (BMR) increased by 0.9 +/- 0.4 MJ/d and daily energy expenditure assessed by whole-body calorimetry (CAL EE) increased by 1.8 +/- 0.5 MJ/d. Total free-living energy expenditure (TEE) measured by doubly labeled water increased by 1.4 +/- 2.0 MJ/d. Activity and thermogenesis (computed as CAL EE--BMR and TEE--BMR) increased by only 0.9 +/- 0.4 and 0.9 +/- 2.1 MJ/d, respectively. All outcomes were consistent with theoretical changes due to the increased fat-free mass, body weight, and energy intake. There was no evidence of any active energy-dissipating mechanisms.
authors.affiliation: Dunn Clinical Nutrition Centre, Cambridge, UK.
authors.forename: E O
authors.initials: EO
authors.lastname: Diaz
authors.forename: A M
authors.initials: AM
authors.lastname: Prentice
authors.forename: G R
authors.initials: GR
authors.lastname: Goldberg
authors.forename: P R
authors.initials: PR
authors.lastname: Murgatroyd
authors.forename: W A
authors.initials: WA
authors.lastname: Coward
mesh_terms: D001481:Basal Metabolism; D001833:Body Temperature Regulation; D001835:Body Weight; D002151:Calorimetry; D002149:Energy Intake; D004734:Energy Metabolism; D005502:Food; D006801:Humans; D008297:Male; D015430:Weight Gain