Nutrition Trial on the Glycaemic Response to High GI Meals Consumed at Morning vs. Evening-The ChroNu Study

Study Overview
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Brief Summary
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Several studies suggest that meal timing plays an important role in the development of obesity and metabolic diseases. Especially in the evening, a high consumption of carbohydrates, which greatly increase blood glucose levels (i.e. unfavourable carbohydrates with a higher glycaemic index (GI)), has been found to adversely affect glycaemic response. However, avoidance of (unfavourable) carbohydrate consumption appears to be particularly problematic for young adults due to its interference with the timing of social life and their chronotype. The chronotype describes individual differences in sleep timing on free days and is most delayed around the age of 20. Young adults are thus prone to be exposed to a dietary misalignment when socially determined schedules, such as early lectures at universities, collide with their biologically determined later chronotype. Therefore, it is hypothesized that dietary misalignment among young adults has detrimental short-term effects on the glucose metabolism. In this nutrition trial, dietary misalignment is induced by providing the same meal rich in carbohydrates with a high glycaemic index (GI) on two separate days at different times: breakfast at 7:00 is assumed to reflect a schedule potentially inducing dietary misalignment among later chronotypes. Vice versa, providing this meal at dinner (20:00) may cause dietary misalignment among earlier chronotypes. Adverse glycaemic responses are expected when the high GI meal is consumed at a time which is deviating from the schedule of the individual chronotype. A regular increase in postprandial glycaemia due to constant dietary misalignment may be important in the development of metabolic diseases.

Detailed Description
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To address the hypothesis that dietary misalignment among young adults has detrimental short-term effects on glucose metabolism, participants will consume a meal rich in high GI carbohydrates on two separate days either at breakfast (7:00) or at dinner (20:00). Glycaemic responses will be monitored by a continuous glucose monitoring device (CGM) (G6, Dexcom, Inc., San Diego, CA). The CGM electrochemically measures subcutaneous interstitial glucose concentrations of each participant during the whole study. A blood glucose meter will be used to verify the functionality of the CGM (CONTOUR®NEXT ONE). The caloric content of the meals will be tailored to the energy needs of the participants based on their age, sex and anthropometric measurements. Participants will be requested to consume the meals without any break. During the controlled nutrition trial, participants will be asked to abstain from alcohol consumption and heavy exercise and not consume any food in addition to that provided or drinks that should be explicitly avoided. To objectively corroborate their chronotype participants will be asked to wear an accelerometer (E4 wristband, Empatica) attached to the wrist during the controlled nutrition trial. Moreover, participants are asked to record their bed times, meal timings, daily routines, and physical activities during the trial. On day 1 and day 8, anthropometric measurements will be performed to compare the body composition (Bioimpedance Analysis, SECA mBCA) before and after the controlled nutrition trial. On day 4, fasting blood samples will be collected. Before the controlled nutrition trial will start, questionnaires on daily routines, food frequency, and chronotype will be carried out. The chronotype is defined as mid-sleep point and assessed by the Munich Chronotype Questionnaire, which is a validated questionnaire. Earlier and later chronotypes will be defined as 20% of the participants with each the earliest and later mid-sleep points among the participants of the ChroNu cohort.

Official Title
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Controlled Nutrition Trial on the Glycaemic Response to Morning and Evening Meals With High Glycemic Index Carbohydrates Among Students With Early and Late Chronotypes-The ChroNu Study

Conditions
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Healthy

Intervention / Treatment
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* Other: Glycaemic response to high GI carbohydrates consumed at morning versus evening meals.


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Healthy students of Paderborn University 18 - 25 years old at time of screening for the ChroNu cohort 18,5 kg/m² < BMI > 30 kg/m² Free of diseases requiring constant or chronic medical treatment (except for oral contraceptives) Willingness to participate in the nutrition trial (8 days) including invasive measurements Fluent knowledge of the German language Exclusion Criteria: students studying nutrition science at the University Paderborn regular smokers pregnancy or lactation chronic diseases: diabetes mellitus (all types), pre-diabetes, individuals with bleeding disorders (thrombocytopenia, haemophilia) contact dermatitis to adhesive plaster or skin disease that prevents the participant from wearing the CGM intake of medication which influence the chronotype: such as antidepressants or sleeping pills shift work in the past 3 months crossing of > 1-time zone in the past 3 months strict vegetarians /vegans individuals having an allergy or intolerance to food that is included in the diet

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 25 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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Accepts Healthy Volunteers

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Basic Science
Allocation: Randomized
Intervention Model: Crossover Assignment
Interventional Model Description: 60 participants will be invited of which 20 participants with an earlier and 20 participants with a later chronotype are expected to finish the study. Participants will consume a meal rich in carbohydrates with a high GI on two separate days at different times. Hence, participants are randomly assigned to one group stratified by chronotype: intake of a meal with a high GI on day 5 either in the morning or in the evening. On day 7, meal timing of the high GI meal is switched. Following a 3 - day observational part on free days, the controlled nutrition trial will last 4 days: run - in (day 4), high GI meal for breakfast/dinner (days 5 / 7), and wash - out (day 6). The trial is a two-arm cross-over study in which each participant serves as his / her own control to account for inter-individual variations in diurnal glycaemic responses.
Masking: None (Open Label)


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: High GI carbs breakfast / dinner<br>Participants will receive a meal rich in high GI carbohydrates for breakfast (day 5) first. After the wash-out day (day 6), the identical meal will be provided for dinner (day 7). | Other: Glycaemic response to high GI carbohydrates consumed at morning versus evening meals.<br>* Controlled nutrition trial on the glycaemic response to morning and evening meals with high glycemic index carbohydrates among students with early and late chronotypes.<br>|
| Experimental: High GI carbs dinner / breakfast<br>Participants will receive a meal rich in high GI carbohydrates for dinner (day 5) first. After the wash-out day (day 6), the same meal will be provided for breakfast (day 7). | Other: Glycaemic response to high GI carbohydrates consumed at morning versus evening meals.<br>* Controlled nutrition trial on the glycaemic response to morning and evening meals with high glycemic index carbohydrates among students with early and late chronotypes.<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Differences in the 2-h pp glycaemic response between the high GI carbohydrate meal consumed for breakfast (7:00) and the high GI carbohydrate meal consumed for dinner (20:00). | 2 hour post prandial response (iAUC) is calculated as the incremental area under the curve of measurements taken within the two hours after the test meals. | 2 hour postprandial after test meals | 
| Differences in the 2-h pp glycaemic variability between the high GI carbohydrate meal consumed for breakfast (7:00) and the high GI carbohydrate meal consumed for dinner (20:00). | the 2-h pp glycaemic variability (MAGE) is calculated as the mean amplitude of glycaemic excursions during the two hours after the test meals, i.e. both resemble summary measures calculated from repeated measurements taken the 2 h pp. | 2 hours postprandial after test meals | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Diurnal differences in the glycaemic response (iAUC) and in response to the high GI carbohydrates for dinner and the high GI carbohydrates for breakfast. | 24 hour post prandial response (iAUC) is calculated as the incremental area under the curve of measurements taken within the 24 hours after the test meals. | 24 hours after test meals | 
| Diurnal differences in the glycaemic variability (MAGE) in response to the high GI carbohydrates for dinner and the high GI carbohydrates for breakfast. | 24-h pp glycaemic variability (MAGE) is calculated as the mean amplitude of glycaemic excursions during the 24 hours after the test meals, i.e. both resemble summary measures calculated from repeated measurements taken the 24 h pp. | 24 hours after test meals | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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chronotype, social jetlag, glycaemic response, glycaemic index, continuous glucose monitoring, body composition