The Effect of Flexitarian, Time-restricted Eating on Cardiometabolic Traits in Normal Weight, Young Men

Study Overview
=================
Brief Summary
-----------------
The goal of this factorial randomized controlled trial is to find out whether time-restricted eating and flexitarian diet (on its own and combined) can improve cardiometabolic health markers in normal weight, young men with metabolic abnormalities? Participants will be assigned to four groups: control, flexitarian, time-restricted eating and time-restricted eating + flexitarian. Investigators will look for men with elevated fasting blood glucose or blood lipids level or blood pressure and with normal body weight and waistline. Participants from the flexitarian group will be asked to follow a diet that has been carefully designed for them by the PI and dietitian for the period of 8 weeks. Participants from the control group will receive general healthy eating recommendations. We aim to investigate if the experiment had any effect on changes in metabolic, inflammation and nutritional markers, blood pressure and body weight and composition. Also, the effect of diets on men's sleep, general wellbeing and satisfaction with treatment will be investigated. The proposed study can test a potentially effective nutritional intervention which is feasible to adopt and sustainable (in line with recent planetary diet recommendations). Confirming its effectiveness can fill the research gap, providing new knowledge and approach to the prevention and treatment of metabolic abnormalities in young, lean men.

Official Title
-----------------
The Effect of Flexitarian, Time-restricted Eating on Cardiometabolic Traits in Normal Weight, Young Men: a Factorial Randomized Controlled Trial (FlexiFast Study)

Conditions
-----------------
Cardiometabolic Syndrome, Glucose Metabolism Disorders, Blood Pressure, Lipid Metabolism Disorders

Intervention / Treatment
-----------------
* Behavioral: Dietary


Participation Criteria
=================
Eligibility Criteria
-----------------
Inclusion Criteria: Males Age 18-40 years Normal body weight At least one of metabolic abnormalities (elevated fasting glucose level - but not diabetes, elevated blood lipids, elevated blood pressure) Exclusion Criteria: Females Age <18 and >40 years Overweight or obesity (BMI>25 kg/m2) WC > 94cm Alcohol >14 units/week Smoking On medication Diabetes or other chronic diseases Vegetarians or vegans Don't own or unable to use a Smartphone with Apple iOS or Android OS

Ages Eligible for Study
-----------------
Minimum Age: 18 Years
Maximum Age: 40 Years

Sexes Eligible for Study
-----------------
Male

Accepts Healthy Volunteers
-----------------
Accepts Healthy Volunteers

Study Plan
=================
How is the study designed?
-----------------

Design Details

Primary Purpose: Prevention
Allocation: Randomized
Intervention Model: Factorial Assignment
Masking: None (Open Label)


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| No Intervention: Control group<br>Habitual diet - healthy eating guidelines provided for ethical reasons, no restrictions on the time of eating | |
| Experimental: Flexitarian diet group<br>Flexitarian diet (FD) will be based on planetary diet recommendations (predominantly plants; pulses and legumes as protein sources, meat and poultry consumed occasionally). Ways to facilitate this diet will be presented in the booklet prepared for them by the PI and a dietitian. | Behavioral: Dietary<br>* Depending on the allocation arm, participants will be advised to follow a particular dietary plan (either flexitarian eating, time-restricted eating or both combined).<br>|
| Experimental: Time-restricted eating group<br>Time restricted eating (TRE) with 6 hour eating window - start and end hour to be an individual choice (some may prefer to consume their meals within an early window, e.g. 10am-4pm, some may prefer to consume their meals later in the day, e.g. 12:00-6pm). However, participants will be asked to be fairly consistent with their choice of their timing of eating hours. During fasting only water will be permitted; | Behavioral: Dietary<br>* Depending on the allocation arm, participants will be advised to follow a particular dietary plan (either flexitarian eating, time-restricted eating or both combined).<br>|
| Experimental: Flexitarian diet & time-restricted eating group<br>Treatment TRE and FD combined. | Behavioral: Dietary<br>* Depending on the allocation arm, participants will be advised to follow a particular dietary plan (either flexitarian eating, time-restricted eating or both combined).<br>|

What is the study measuring?
-----------------
Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Change in glucose homeostasis | Change in fasting glucose concentration [mg/dL]. Blood samples will be collected after the overnight fast and the analysis will be performed on the Cobas Integra 400 plus analyzer. | baseline, after 8 weeks and after 20 weeks from baseline | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Change in total cholesterol (TC) | The blood serum concentration of total cholesterol (in mmol/L). Blood samples will be collected after the overnight fast and the analysis will be performed on the Cobas Integra 400 plus analyzer. | baseline, after 8 weeks and after 20 weeks from baseline | 
| Change in high-density lipoprotein (HDL) cholesterol | The blood serum concentration of high-density lipoprotein cholesterol (in mmol/L). Blood samples will be collected after the overnight fast and the analysis will be performed on the Cobas Integra 400 plus analyzer. | baseline, after 8 weeks and after 20 weeks from baseline | 
| Change in low-density lipoprotein (LDL) cholesterol | The blood serum concentration of low-density lipoprotein cholesterol (in mmol/L). Blood samples will be collected after the overnight fast and the analysis will be performed on Cobas Integra 400 plus analyzer. | baseline, after 8 weeks and after 20 weeks from baseline | 
| Change in serum triglycerides (TG) | The concentration of serum triglycerides (in mmol/L). Blood samples will be collected after the overnight fast and the analysis will be performed on Cobas Integra 400 plus analyzer. | baseline, after 8 weeks and after 20 weeks from baseline | 
| Change in body weight | Body weight (in kg) will be measured using a digital medical scale witl stadiometer. | baseline, after 8 weeks and after 20 weeks from baseline | 
| Change in body mass index (BMI) | The measured values of body height and weight will be used for the calculation of body mass index (in kg/m^2). | baseline, after 8 weeks and after 20 weeks from baseline | 
| Change in body fat mass percentage | Determination of body fat percentage will be performed using SECA® mBCA 515 analyser | baseline, after 8 weeks and after 20 weeks from baseline | 
| Change in waist circumference | Waist circumference measuring (in cm) will be performed using a non-strechable measuring tape. | baseline, after 8 weeks and after 20 weeks from baseline | 
| Change in waist-to-hip ratio | The waist-to-hip ratio will be calculated from the measured values of waist and hip circumferences: waist circumference (cm) / hip circumference (cm). | baseline, after 8 weeks and after 20 weeks from baseline | 
| Change in visceral adipose tissue (VAT) | Determination of abdominal fat volume will be measured in litres and performed using SECA® mBCA 515 analyser | baseline, after 8 weeks and after 20 weeks from baseline | 
| Change in inflammatory markers-1 | interleukin-6 [pg/mL] - COBAS e411 analyser | baseline, after 8 weeks and after 20 weeks from baseline | 
| Change in inflammatory markers-2 | C-reactive protein (CRP) [mg/L] - COBAS Integra 400 Plus analyser | baseline, after 8 weeks and after 20 weeks from baseline | 
| Change in nutrition markers-1 | Homocysteine [μmol/L] - COBAS Integra 400 Plus analyser | baseline, after 8 weeks and after 20 weeks from baseline | 
| Change in nutrition markers-2 | Vitamin B12 [pg/mL] - COBAS e411 analyser | baseline, after 8 weeks and after 20 weeks from baseline | 
| Change in insulin concentration | Insulin [units/mL] - COBAS e411 analyser | baseline, after 8 weeks and after 20 weeks from baseline | 
| Change in haemoglobin glycosylated (HbA1c) concentration | HbA1c [mmol/l] - COBAS e411 analyser | baseline, after 8 weeks and after 20 weeks from baseline | 
| Change in systolic and diastolic blood pressure | The assessment of blood pressure (in mmHg) will be performed prior to and immediately after the intervention using electronic monitor (Omron M3 Intellisense Automatic Blood Monitor, Omron Healthcare, Mannheim, Germany). | baseline, after 8 weeks and after 20 weeks from baseline |