title: The effect of breakfasts varying in glycemic index and glycemic load on dietary induced thermogenesis and respiratory quotient.
abstract: OBJECTIVE
  Glycemic index (GI) and Glycemic Load (GL) are parameters of carbohydrate bioavailability able to influence risk of chronic diseases. GL can be lowered either by reducing carbohydrate intake or by reducing the GI of the carbohydrate moiety of a mixed meal. These two approaches might have a different impact on Dietary-Induced Thermogenesis (DIT) and preferential substrate oxidation in the postprandial period, which are variables known to be involved in the regulation of body weight and body composition. This dietary, crossover intervention trial was designed to evaluate the effect on DIT and Respiratory Quotient (RQ) of three isocaloric breakfasts different in GI and/or GL (high GI and high GL [HGI-HGL] vs. low GI and low GL [LGI-LGL]; vs. high GI and low GL [HGI-LGL]) followed by a standard meal.
  
  
  RESULTS
  RQ and DIT were measured in 16 lean young males by indirect calorimetry for 8h. DIT resulted significantly higher after the LGI-LGL compared to the HGI-HGL breakfast (p<0.05). Postprandial changes in RQ differed among all breakfasts (p<0.001). RQ increased from baseline after the two breakfasts with highest carbohydrate content and significantly more after the HGI-HGL than after the LGI-LGL (p<0.02), whereas it decreased after the HGI-LGL breakfast, which contained a higher amount of fat.
  
  
  CONCLUSIONS
  Reducing the GL of a meal by reducing GI seems an effective strategy to increase energy expenditure while maintaining a good rate of lipid oxidation. This might be related to different profiles of postprandial hormones affecting substrate oxidation.
authors.affiliation: Human Nutrition Unit, Department of Public Health, University of Parma, Via Volturno, 39, 43100 Parma, Italy. francesca.scazzina@unipr.it
authors.forename: F
authors.initials: F
authors.lastname: Scazzina
authors.forename: D
authors.initials: D
authors.lastname: Del Rio
authors.forename: L
authors.initials: L
authors.lastname: Benini
authors.forename: C
authors.initials: C
authors.lastname: Melegari
authors.forename: N
authors.initials: N
authors.lastname: Pellegrini
authors.forename: E
authors.initials: E
authors.lastname: Marcazzan
authors.forename: F
authors.initials: F
authors.lastname: Brighenti
mesh_terms: D000328:Adult; D000704:Analysis of Variance; D001786:Blood Glucose / Q000378:metabolism; D001823:Body Composition; D001835:Body Weight; D018592:Cross-Over Studies; D004032:Diet; D004040:Dietary Carbohydrates / Q000008:administration & dosage*; D004734:Energy Metabolism; D038321:Glycemic Index; D006801:Humans; D008297:Male; D010101:Oxygen Consumption; D019518:Postprandial Period; D012307:Risk Factors; D022722:Thermogenesis; D055815:Young Adult
chemical_list: D001786:Blood Glucose; D004040:Dietary Carbohydrates