Glycemic Index and Brain Function
The Effects of Dietary Glycemic Index on Brain Function
Aperçu de l'étude
Description détaillée
Most individuals have great difficulty following reduced calorie diets because they experience increased hunger. This process is regulated by specific brain areas. Though many psychological and environmental factors are involved, physiological effects of diet may have a significant impact. The postprandial rise in blood glucose, quantified by the glycemic index (GI), is of particular interest. High GI meals elicit hormonal events that limit availability of metabolic fuels, causing hunger and overeating, especially in people with high insulin secretion.
Our aim is to examine how postprandial changes after high versus low GI meals affect hunger and brain function in areas of intake control. Specifically, we speculate that obese individuals will demonstrate functional changes in brain areas of intake control and increased hunger after a high versus low GI meal.
We will recruit obese, young adults and quantify their insulin secretion during a 2-hour oral glucose tolerance test. A brief practice MRI session will serve to familiarize the subjects with the scanning process. During the two test sessions, standardized test meals with high versus low GI will be given in a randomized, blinded cross-over design. Serial blood levels of hormones, metabolic fuels, and metabolites will be correlated with perceived hunger, and a perfusion MRI scan will be performed to assess brain activation during the late postprandial phase, at the nadir of blood sugar and insulin levels (4 hours postprandial).
This work will inform an integrated physiological model relating peripheral postprandial changes to brain function and hunger. In addition, findings may provide evidence of a novel diet-phenotype, in which baseline clinical characteristics can be used to predict which weight loss diet will work best for a specific individual. Metabolite profiling might shed light on the mechanisms linking diet composition to brain function, and provide feasible clinical markers of the identified phenotype to facilitate translation into practice.
Type d'étude
Inscription (Réel)
Phase
- N'est pas applicable
Contacts et emplacements
Lieux d'étude
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Massachusetts
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Boston, Massachusetts, États-Unis, 02215
- Beth Israel Deaconess Medical Center
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Boston, Massachusetts, États-Unis, 02115
- Children's Hospital Boston
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Boston, Massachusetts, États-Unis, 02215
- Brigham and Women's Hospital
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Critères de participation
Critère d'éligibilité
Âges éligibles pour étudier
Accepte les volontaires sains
Sexes éligibles pour l'étude
La description
Inclusion criteria
- Males age 18 to 35 years
- BMI less than or equal to 25 for age and gender
Exclusion criteria
- weight > 300 lbs
- largest body circumference > 144cm
- body shape incompatible with MRI scanner or equipment
- MRI exclusion criteria
- large fluctuations in body weight (5% over preceding 6 months, 2.5% during the study)
- known medical problems that may affect metabolism or hormones
- diabetes mellitus (fasting plasma glucose ≥126 mg/dL)
- other abnormal laboratory screening tests
- taking any medications or dietary supplements that might affect body weight, appetite, or energy expenditure
- smoking or illicit substance abuse
- high levels of physical activity (>30 minutes per day, > 4days per week)
- currently following a weight loss diet
- allergies or intolerance to eggs, vanilla extract, equal, canola oil, milk, cornstarch, corn syrup
Plan d'étude
Comment l'étude est-elle conçue ?
Détails de conception
- Objectif principal: Traitement
- Répartition: Randomisé
- Modèle interventionnel: Affectation croisée
- Masquage: Quadruple
Armes et Interventions
Groupe de participants / Bras |
Intervention / Traitement |
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Comparateur actif: Low GI
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Subjects will be instructed to consume a liquid test meal with a low GI over 5 minutes after baseline laboratory evaluations.
The low and high GI meal contain similar amounts of milk, oil, dried egg whites, equal, and vanilla extract.
The low GI meal corn-starch as a carbohydrate.
Both meals have similar macronutrient composition (60% carbohydrate, 15% protein, 25% fat), micronutrient profiles, physical properties, palatability and sweetness.
The high vs. low GI meals have a predicted difference in GI of 90 vs. 40, and consistent with this prediction, a pilot study in obese young adults found a 2.2-fold difference in glycemic response (p<0.001).
The test meals will provide 25% of individual daily energy requirements.
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Expérimental: High GI
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Subjects will be instructed to consume a liquid test meal with a high GI over 5 minutes after baseline laboratory evaluations.
The low and high GI meal contain similar amounts of milk, oil, dried egg whites, equal, and vanilla extract.
The high GI meal contains corn-syrup as a carbohydrate.
Both meals have similar macronutrient composition (60% carbohydrate, 15% protein, 25% fat), micronutrient profiles, physical properties, palatability and sweetness.
The high vs. low GI meals have a predicted difference in GI of 90 vs. 40, and consistent with this prediction, a pilot study in obese young adults found a 2.2-fold difference in glycemic response (p<0.001).
The test meals will provide 25% of individual daily energy requirements.
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Que mesure l'étude ?
Principaux critères de jugement
Mesure des résultats |
Délai |
|---|---|
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Blood Flow in Brain Areas of Intake Control.
Délai: 4 hours postprandial
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4 hours postprandial
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Mesures de résultats secondaires
Mesure des résultats |
Description de la mesure |
Délai |
|---|---|---|
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Subjective Hunger Rating
Délai: Every 30 minutes for 5 hours.
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Every 30 minutes for 5 hours.
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Blood Glucose Level
Délai: Every 30 minutes for 5 hours.
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Every 30 minutes for 5 hours.
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Blood Insulin Level
Délai: Every 30 minutes for 5 hours
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Every 30 minutes for 5 hours
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Blood Glucagon Level
Délai: Every 30 minutes for 5 hours.
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Every 30 minutes for 5 hours.
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Blood Growth Hormone Level
Délai: Every 30 minutes for 5 hours.
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Every 30 minutes for 5 hours.
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Blood Epinephrine Level
Délai: Every 30 minutes for 5 hours.
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Every 30 minutes for 5 hours.
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Blood Fatty Acids Level
Délai: Every 30 minutes for 5 hours.
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measuring metabolite profiles
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Every 30 minutes for 5 hours.
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Collaborateurs et enquêteurs
Parrainer
Les enquêteurs
- Directeur d'études: Belinda S Lennerz, MD, PhD, Boston Children's Hospital
- Chercheur principal: David Alsop, PhD, Beth Israel Deaconess Medical Center
Publications et liens utiles
Dates d'enregistrement des études
Dates principales de l'étude
Début de l'étude
Achèvement primaire (Réel)
Achèvement de l'étude (Réel)
Dates d'inscription aux études
Première soumission
Première soumission répondant aux critères de contrôle qualité
Première publication (Estimation)
Mises à jour des dossiers d'étude
Dernière mise à jour publiée (Estimation)
Dernière mise à jour soumise répondant aux critères de contrôle qualité
Dernière vérification
Plus d'information
Termes liés à cette étude
Autres numéros d'identification d'étude
- RA-003
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