Glycemic Index and Brain Function

NCT ID: NCT01064778

Last Updated: 2012-02-02

Basic Information

• Recruitment Status: COMPLETED
• Clinical Phase: NA
• Total Enrollment: 12 participants
• Study Classification: INTERVENTIONAL
• Study Start Date: 2010-02-28
• Study Completion Date: 2011-09-30

Brief Summary

The investigators propose examine the effects of the dietary factor glycemic index (GI) on brain areas that control food intake and hunger. This knowledge could help design dietary approaches that decrease hunger, and thus promote new weight loss strategies.

Detailed Description

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.

Conditions

Obesity

Study Design

• Allocation Method: RANDOMIZED
• Intervention Model: CROSSOVER
• Primary Study Purpose: TREATMENT
• Blinding Strategy: QUADRUPLE

Study Groups

Low GI

Group Type: ACTIVE_COMPARATOR

Low GI

Intervention Type: OTHER

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.

High GI

Group Type: EXPERIMENTAL

High GI

Intervention Type: OTHER

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.

Interventions

Low GI

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.

Intervention Type: OTHER

High GI

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.

Intervention Type: OTHER

Eligibility Criteria

Inclusion Criteria

1. Males age 18 to 35 years

2. BMI less than or equal to 25 for age and gender

Exclusion Criteria

1. weight > 300 lbs

2. largest body circumference > 144cm

3. body shape incompatible with MRI scanner or equipment

5. large fluctuations in body weight (5% over preceding 6 months, 2.5% during the study)

6. known medical problems that may affect metabolism or hormones

7. diabetes mellitus (fasting plasma glucose ≥126 mg/dL)

8. other abnormal laboratory screening tests

9. taking any medications or dietary supplements that might affect body weight, appetite, or energy expenditure

10. smoking or illicit substance abuse

11. high levels of physical activity (>30 minutes per day, > 4days per week)

12. currently following a weight loss diet

13. allergies or intolerance to eggs, vanilla extract, equal, canola oil, milk, cornstarch, corn syrup

• Minimum Eligible Age: 18 Years
• Maximum Eligible Age: 35 Years
• Eligible Sex: MALE
• Accepts Healthy Volunteers: Yes

Sponsors

Boston Children's Hospital

OTHER

Sponsor Role: collaborator

Brigham and Women's Hospital

OTHER

Sponsor Role: collaborator

Beth Israel Deaconess Medical Center

OTHER

Sponsor Role: lead

Responsible Party

David Alsop

Director of MRI Research

Responsibility Role: PRINCIPAL_INVESTIGATOR

Principal Investigators

David S Ludwig, MD, PhD

Role: PRINCIPAL_INVESTIGATOR

Boston Children's Hospital

David Alsop, PhD

Role: PRINCIPAL_INVESTIGATOR

Beth Israel Deaconess Medical Center

Belinda S Lennerz, MD, PhD

Role: STUDY_DIRECTOR

Boston Children's Hospital

Locations

Children's Hospital Boston

Boston, Massachusetts, United States

Beth Israel Deaconess Medical Center

Boston, Massachusetts, United States

Brigham and Women's Hospital

Boston, Massachusetts, United States

Countries

United States

References

Lennerz BS, Alsop DC, Holsen LM, Stern E, Rojas R, Ebbeling CB, Goldstein JM, Ludwig DS. Effects of dietary glycemic index on brain regions related to reward and craving in men. Am J Clin Nutr. 2013 Sep;98(3):641-7. doi: 10.3945/ajcn.113.064113. Epub 2013 Jun 26.

Reference Type: DERIVED

PMID: 23803881 (View on PubMed)

Other Identifiers

RA-003

Identifier Type: -

Identifier Source: org_study_id