title: Effects of weight loss on substrate oxidation, energy expenditure, and insulin sensitivity in obese individuals.
abstract: To evaluate the effect of weight loss on substrate oxidation, energy expenditure, and insulin sensitivity we studied 12 obese subjects (body mass index 33.4 +/- 1.1) before and after 6 wk of a very-low-calorie diet (VLCD) with euglycemic insulin clamp in combination with indirect calorimetry. Body weight decreased from 105.3 +/- 4.6 to 94.1 +/- 4.0 kg (P less than 0.001) and fat mass from 47.2 +/- 3.6 to 37.7 +/- 3.0 kg (P less than 0.001). Total glucose disposal during insulin clamp increased from 30.4 +/- 4.3 to 38.4 +/- 4.4 mumol.kg lean body mass (LBM)-1.min-1 (P less than 0.05), insulin-stimulated glucose oxidation from 14.3 +/- 4.6 to 19.1 +/- 1.4 mumol.kg LBM-1.min-1 (P less than 0.05), and non-oxidative glucose metabolism from 16.0 +/- 3.8 to 19.3 +/- 3.6 mumol.kg LBM-1.min-1 (NS). Lipid oxidation decreased in the basal state (P less than 0.05) and during the insulin clamp (P less than 0.01). The basal rate of energy expenditure decreased from 99.1 +/- 4.6 to 88.5 +/- 2.7 kJ.kg LBM-1.min-1 (P less than 0.05) after weight reduction. A reduction in fat mass achieved by VLCD is associated with reduced lipid oxidation and, because of substrate competition, enhanced glucose oxidation. The physiological consequence is improved insulin sensitivity.
authors.affiliation: Department of Psychiatry, Helsinki University Hospital, Finland.
authors.forename: A
authors.initials: A
authors.lastname: Franssila-Kallunki
authors.forename: A
authors.initials: A
authors.lastname: Rissanen
authors.forename: A
authors.initials: A
authors.lastname: Ekstrand
authors.forename: A
authors.initials: A
authors.lastname: Ollus
authors.forename: L
authors.initials: L
authors.lastname: Groop
mesh_terms: D000328:Adult; D001786:Blood Glucose / Q000032:analysis; D001835:Body Weight; D004038:Diet, Reducing; D004734:Energy Metabolism; D005215:Fasting; D005260:Female; D005947:Glucose / Q000378:metabolism; D006801:Humans; D007328:Insulin / Q000494:pharmacology*; D050356:Lipid Metabolism; D008297:Male; D009765:Obesity / Q000378:metabolism* / Q000473:pathology; D010084:Oxidation-Reduction
chemical_list: D001786:Blood Glucose; D007328:Insulin; D005947:Glucose