A Free-living, Walking-based, Exercise Programme, With Exercise Timed Relative to Breakfast, to Improve Metabolic Health in People Living With Obesity: A Feasibility Study
Phase: NA
Conditions: Metabolic Disease, Insulin Resistance
Sponsor: Liverpool John Moores University

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Protocol  
 
The effects of a fasted versus fed remote walking-based 
training programme on glycaemic control in overweight 
individuals 
 
Short title: Can fasted exercise enhance glycaemic control in overweight 
individuals? 
 
 
Investigators: 
Ms Jennifer Barrett 
PhD Student, School of Sport and Exercise Sciences, Liverpool John Moores University 
 
Dr Juliette Strauss 
Lecturer in Exercise and Health Metabolism, School of Sport and Exercise Sciences, Liverpool 
John Moores University 
 
Professor Daniel Cuthbertson 
Reader and Honorary Consultant Physician, University of Liverpool and Aintree University 
Hospital 
 
Professor Anton Wagenmakers 
Professor of Exercise Metabolism, School of Sport and Exercise Sciences, Liverpool John Moores 
University 
 
Dr Sam Shepherd 
Lecturer in Sport and Exercise Nutrition, School of Sport and Exercise Sciences, Liverpool John 
Moores University 
 
Background and rational: 
 
According to recent statistics, 64.3% of the UK adult population are now classified as 
overweight or obese.  People who are overweight or obese have high levels of fat in their 
muscle, which is linked to insulin resistance and ultimately the development of type 2 diabetes.  
Interestingly, healthy people also have high levels of muscle fat, but they are highly insulin 
sensitive.  This is because healthy people are able to burn this fat to generate energy during 
exercise, resulting in a reduction in the amount of fat in the muscle that can then be replaced 
with a meal. Healthy people who regularly breakdown these stores during exercise, and 
rebuild them following exercise, have a high turnover of their fat stores.  However, people 
who are overweight or obese have difficulty using muscle fat during exercise. Fasted exercise 
has been shown to increase the reliance on muscle fat stores during exercise and is well 
utilised in trained individuals to improve their capacity to burn fat.  Whether this type of 
exercise has the potential to be beneficial in less healthy individuals is less well known.  Most 
importantly, whether this simple exercise-nutrition strategy can be implemented into the daily 
lives of less healthy individuals to improve glycaemic control and reduce type 2 diabetes risk 
now requires investigation.   
 

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Aim: To determine whether a remote 12-week fasted walking-based intervention can 
increase glycaemic control compared to a fed group.  
 
Participants:  N = 34 
 
Inclusion criteria 
You are likely to be eligible for this study if you fulfil the following criteria: 
• Aged 20-60 years 
• BMI >28 kg.m-2 
• Not currently using any anti-diabetes medication 
• Physically inactive (performing less than two 30 min structured exercise sessions per 
week for the last year) 
• Not pregnant or currently breast feeding 
• Pre-menopausal or peri-menopausal  
• Not currently involved in a weight loss programme or using weight loss medication 
 
Exclusion Criteria 
(Meeting any of the following criteria will prevent you from participating in the study)  
• Involved in regular exercise (engaged in more than 3 sessions of structured exercise 
of >30 min per week) 
• Currently using anti-diabetes medication (e.g. insulin, metformin) 
• Pregnant or breast feeding 
• Currently engaged in active weight loss programme or using weight loss medication  
• Diagnosed with chronic kidney disease 
• Post-menopausal 
 
Plan of investigation  
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Consent  
Pre-testing: Bleep test, CGM, waist-to-hip ratio, food diary, baseline bloods 
Randomized into Fasted or Fed group 
Fasted Group 
(n= 17) 
Fed Group 
(n= 17) 
12-week walking-exercise programme  
Post-testing: Bleep test, CGM, waist-to-hip ratio, food diary, baseline bloods 

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Consent and pre-screening:  
 
Participants will be sent a participant information sheet after expressing interest via email 
and will have the opportunity to contact with any questions about the study before 
providing consent via email.  
 
Questionnaire: Participants will complete a Readiness to Exercise questionnaire and send 
via email to ensure they are fit to undertake exercise as part of the study.   
 
 
Pre-testing: 
 
Waist-to-hip ratio and weight: Participants will be provided with a tape measure and 
instructions on how to measure waist circumference and hip circumference. From this, waist-
to-hip ratio will be calculated. Additionally, participants will be asked to use their own scales 
to provide their weight (if they don’t have any they will be provided).  
 
Blood pressure: (pending Matts suggestion for this) 
 
Baseline blood sample: Participants will receive blood sample kits containing (Thriva) full 
instructions that will be used to measure fasting insulin, glucose, lipid profile, HbA1c, 
cholesterol (includes triglycerides), liver enzymes (ALT usually elevated in people with 
NAFLD). A researcher will be available to video call if needed while these are being 
completed.  
 
CGM: Participants will receive a continuous blood glucose monitor that contains full 
instructions to fit and use. These will be worn for two weeks – 1 week before the intervention 
and during the first week of the intervention (see Fig. 1). 
 
Diet: Participants will receive a food diary to record their habitual dietary intake for three 
days (24 hours after the CGM is fitted). During the first week on the intervention they will 
also be asked to write down what they eat for lunch on the days they exercise. 
 
Fitness test: Participants will receive a polar beat heart rate monitor and instructions on 
how to download an app containing a bleep test protocol. They will be asked to complete the 
bleep test wearing the HR monitor at least 48 hours before they begin the intervention.  
 
Exercise intervention: 
 
Pairs of participants from each group (matched for gender, age, BMI and) will be randomized 
to undertake 12 weeks of steady walking in either a fasted state (before breakfast each day) 
or a fed state (after breakfast each day). They will be asked to eat the same breakfast on each 
day they complete the exercise, whether it is before or after.  
Walking sessions will be 4 times per week and will be two continuous sessions (~50% HR 
max) and two interval sessions (3 minutes at 40% HR max, 3 minutes 80% HR max) monitored 
by the polar beat app. Participants will initially walk for 30 minute sessions in week 1 and this 
will increase by 5 minutes each week until they are completing 4x 60 minute sessions per 
week (see table.1).  

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A CGM will be in place during week 1 to measure the glycaemic response to exercise. And a 
second CGM will be inserted at the beginning of week 12 to see the changes in glycaemic 
control on exercise days and will remain in place for post-intervention CGM monitoring.  
 
Post-testing:  
 
The post intervention assessments will be identical in all aspects to the pre-intervention 
assessments and will begin ≥72 hours after the final training session. 
 
Proposed analysis: 
 
Adherence: From the training data, we will monitor adherence to the study intervention since 
this is remotely ran. We will also monitor whether participants hit their target HR zones 
during each exercise bout.  
 
Blood samples: All blood samples will be analysed by Thriva. 
 
CGM: The 24 h glycaemic profile obtained during the CGM period will be used to determine 
average glucose levels, and the prevalence of hyperglycaemia and hypoglycaemia.  Based on 
the ADA/EASD guidelines, the prevalence of hyperglycaemia and hypoglycaemia will be 
defined as the total time during which glucose concentrations are >10 mmol.L-1 or <3.9 
mmol.L-1, respectively.  The primary outcome from the CGM data will be the time spent in 
range (3.9 – 10 mmol.L-1). 
 
 
 
 
 
 
 

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Figure 1. Plan of CGM data collection. Participants will wear a CGM at two time points; once at the 
beginning of the study and once at the end. Each CGM time point will measure one resting week 
and one intervention week. 

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Table 1. An outline of the walking-based exercise programme. All participants will follow the same 
intervention make up of 4 sessions per week; 2 continuous walking sessions and 2 interval walking 
sessions.