Low Versus High-glycemic Index Post-exercise Diets for Improving Metabolism and Body Composition

Endurance Training and Post-exercise Low Glycemic Index Recovery Diet for Improving Postprandial Triglycerides

Postprandial triglycerides are a strong risk factor for heart disease. The purpose is to assess the effects of a low-glycemic versus high-glycemic meal after 90 minute exercise sessions that are done 4 times a week for 6 weeks on postprandial triglyceride level. Secondary measurements include other lipids and body composition.

Study Overview

• Status: Completed
• Conditions: Hypercholesterolemia
• Intervention / Treatment: Dietary supplement: Low glycemic index post-exercise diet; Dietary supplement: High glycemic index post-exercise diet

Detailed Description

The increase in triglycerides after a meal (i.e. postprandial triglycerides) is a strong risk factor for cardiovascular disease. Overweight/obese individuals have a greater triglyceride response to the same meal compared to lean individuals; therefore they are at greater risk. If exercise is performed the evening before a high-fat breakfast, the postprandial levels of triglycerides after the breakfast are reduced; however, if high glycemic index (GI) foods are consumed after the exercise session, the benefits of exercise on next-day postprandial triglycerides is negated. The investigators recently showed (HSFC funded) that consuming low GI foods after exercise is similar to fasting after exercise and superior to consumption of high GI foods for lowering next-day postprandial triglycerides. Low GI food was also superior for increasing fat oxidation, and lowering insulin, and low and very low density lipoproteins and preventing a decrease in high density lipoproteins. The benefits of an acute exercise session followed by low GI food consumption is now clear; however, it is not known whether this practice over weeks of exercise training results in accumulated and sustained benefits.

The purpose of this study is to determine the chronic effects of consuming low compared to high GI foods after exercise sessions over six weeks in overweight and obese individuals.

Twenty-four overweight and obese males and females will be randomized to consume either high or low GI foods immediately after exercise sessions (four sessions per week, 90 minutes per session, six weeks). At all other times of the day over the six weeks, they will be supplied a moderate GI diet, with calories and macronutrients based on four-day food diaries completed before the study. Two weeks before the intervention, participants will be required to go on the moderate GI diet, as a lead-in. One week into the lead-in, a baseline test will be done to determine postprandial metabolic responses (i.e. triglycerides, low and very low density lipoproteins, high density lipoproteins, insulin, and fat oxidation) after a morning high-fat breakfast. A week later, the same postprandial testing will be carried out the morning after the first exercise and post-exercise consumption of a low or high GI recovery meal. Participants will continue the training and post-exercise food consumption for the next six weeks, with postprandial measures taken again following the final exercise and feeding session. Body composition and aerobic fitness will be determined before and after the six week intervention.

The investigators hypothesize that the low GI post-exercise feeding will be superior to the high GI post-exercise feeding for reducing body fat, improving fat oxidation, and reducing postprandial triglycerides, insulin and other harmful lipids. The results of the study will provide clinicians, exercise professionals and dietitians unique and experimentally tested strategies for their clients to lose body fat and improve metabolic profiles, to reduce the risk of heart disease.

• Study Type: Interventional
• Enrollment (Actual): 25
• Phase: Not Applicable

Contacts and Locations

Study Locations

• Canada
  • Saskatchewan
    • Saskatoon, Saskatchewan, Canada, S7N 5B2
      • University of Saskatchewan

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 18 years to 44 years (ADULT)
• Accepts Healthy Volunteers: Yes
• Genders Eligible for Study: All

Description

Inclusion Criteria:

• Overweight or obese (BMI 25 or greater)

Exclusion Criteria:

• Smokers
• Diabetic
• Taking medications that affect carbohydrate or lipid metabolism

Study Plan

How is the study designed?

Design Details

• Primary Purpose: PREVENTION
• Allocation: RANDOMIZED
• Interventional Model: PARALLEL
• Masking: NONE

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
EXPERIMENTAL: Low glycemic index post-exercise diet; Lentil-based post-exercise meal	Dietary supplement: Low glycemic index post-exercise diet; Feeding of a low-glycemic index, lentil meal after 90 minutes of walking exercise
ACTIVE_COMPARATOR: High glycemic index post-exercise diet; Instant potato, white bread, and egg white post-exercise meal	Dietary supplement: High glycemic index post-exercise diet; Feeding of a high-glycemic index meal (i.e. instant mashed potatoes, white bread, egg whites) after 90 minutes of walking exercise

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Postprandial triglycerides	Triglyceride from serum	Change from baseline to 1 week and 6 weeks

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Postprandial cholesterol	Cholesterol from serum	Change from baseline to 1 week and 6 weeks
Postprandial low density lipoprotein	Low density lipoprotein from serum	Change from baseline to 1 week and 6 weeks
Postprandial high density lipoprotein	High density lipoprotein from serum	Change from baseline to 1 week and 6 weeks
Postprandial glucose	Glucose from serum	Change from baseline to 1 week and 6 weeks
Postprandial insulin	Insulin from serum	Change from baseline to 1 week and 6 weeks
Fasting Triglyceride	Triglyceride from serum	Change from baseline to 1 week and 6 weeks
Fasting cholesterol	Cholesterol from serum	Change from baseline to 1 week and 6 weeks
Fasting LDL-cholesterol	LDL from serum	Change from baseline to 1 week and 6 weeks
Fasting HDL-cholesterol	HDL from serum	Change from baseline to 1 week and 6 weeks
Fasting glucose	Glucose from serum	Change from baseline to 1 week and 6 weeks
Fasting Insulin	Insulin from serum	Change from baseline to 1 week and 6 weeks
Postprandial fat oxidation	Fat oxidation assessed by expiratory gases	Change from baseline to 1 week and 6 weeks
Fat mass	Fat mass assessed by dual energy x-ray absorptiometry	Change from baseline to 6 weeks
Waist Girth	Waist girth assessed by a measurement tape	Change from baseline to 6 weeks

Collaborators and Investigators

• Sponsor: University of Saskatchewan
• Collaborators: Heart and Stroke Foundation of Canada

Study record dates

Study Major Dates

• Study Start (ACTUAL): July 15, 2018
• Primary Completion (ACTUAL): September 30, 2019
• Study Completion (ACTUAL): December 30, 2019

Study Registration Dates

• First Submitted: June 27, 2018
• First Submitted That Met QC Criteria: July 12, 2018
• First Posted (ACTUAL): July 16, 2018

Study Record Updates

• Last Update Posted (ACTUAL): June 11, 2020
• Last Update Submitted That Met QC Criteria: June 10, 2020
• Last Verified: June 1, 2020

More Information

Terms related to this study

• Additional Relevant MeSH Terms: Metabolic Diseases; Lipid Metabolism Disorders; Hyperlipidemias; Dyslipidemias; Hypercholesterolemia
• Other Study ID Numbers: 17-171

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No