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Take part in our study about the effects of intermittent carbohydrate restriction on health

Join our study that looks at how short periods of carbohydrate restriction impact health, and whether a new mobile health app can help with lifestyle adherence.

Research background

Understanding what lifestyle strategies can be effective for preventing and managing obesity-related conditions such as type 2 diabetes, heart disease and metabolic syndrome is a public health priority.

Previous studies suggest that limiting how many carbohydrates we eat (from foods like pasta, bread, potatoes and sugar) can help with weight loss and improve certain aspects of health, such as blood sugar and fat levels. It is still unknown whether shorter periods of restricting carbohydrates can have similar effects.

The study from the Centre for Nutrition, Exercise and Metabolism aims to compare two diets that temporarily limit carbohydrate intake at different time frames to see if they work and, if they do, understand how. We also hope to learn whether a new mobile phone application is useful in following diets like these and tracking progress.

Study dates

  • Start date: 23 May 2023
  • End date: 1 June 2026

Participant eligibility

We are looking for volunteers who:

  • are aged between 18-65 years
  • have a waist circumference of ≥ 94 cm (37 inches) if male and ≥ 80 cm (31.5 inches) if female, or a body mass index (BMI) above 25 kg/m2
  • have a stable body weight (in the last 3 months)

Exclusion criteria

You may not be able to participate if you:

  • have a body weight of ≥ 120 kg
  • are planning to undertake other lifestyle changes during the study to manage weight over the next 2 months (e.g. change in diet or activity levels)
  • were currently or previously diagnosed with an eating disorder (e.g. anorexia)
  • were diagnosed with chronic conditions (e.g. type 2 diabetes, coronary heart disease, cancer, chronic kidney disease, etc.)
  • use medication that may impact your weight, blood glucose or cholesterol levels
  • are currently or recently pregnant (within last 6 months), planning to get pregnant or currently lactating
  • donated more than 500 ml of blood in the last 3 months
  • have dietary restrictions to ingredients in test meals (e.g. gluten and dairy)

Your data

Throughout the study, all documents will only contain your unique study code which you will be assigned if you enrol. Any identifiable personal data will be kept on a password-protected file on the University’s servers, in accordance with the current UK Data Protection regulations.

Relevant ethics approval information

This study has been reviewed and given a favourable opinion by Newcastle and North Tyneside 2 research Ethics Committee (IRAS Project ID 323721).

What you'll do

Over the course of the study, you will take part in four lab visits, and complete a 4-week dietary intervention and a 4-week digital phase, while monitoring your lifestyle for a total of 10 weeks.

A blood sample in a test tube

Laboratory visit 1 (around 1 hour):

Body measurements, a scan to measure body composition, and a 15-minute treadmill walk while measuring your heart rate and breathing.

Monitoring phase (2 weeks):

Monitoring of your current lifestyle through wearable devices (such as a smartwatch, activity monitor and a continuous glucose monitor), food diaries and mobile applications.

Laboratory visit 2 (around 7.5 hours):

Body measurements, collection of breath samples and a measure of blood pressure. A fat and optional muscle sample will then be collected. You will then be asked to drink a glucose (sugar) drink, after which we will regularly collect blood and breath samples for 3 hours. We will then provide you with a meal for lunch, after which we will carry out the same measurements for 2 hours.

Dietary phase (4 weeks):

We will ask you to follow one of the following diets for 4 weeks: 1) Restriction of carbohydrates on two days in a row each week 2) Restriction of carbohydrates after 4pm each day 3) No changes to your current diet You will also be asked to continue monitoring your lifestyle throughout.

Laboratory visit 3 (around 8 hours):

Identical as visit 2 except a body composition scan will be included.

Digital phase (4 weeks):

We will ask you to test out a mobile health-tracking application (‘Metabolism’) that provides education and recommendations tailored specifically to you, while continuing to monitor your lifestyle.

Laboratory visit 4 (around 6 hours):

Body measurements, a body composition scan, collection of breath samples and a measure of blood pressure. You will then be asked to consume a drink of glucose, after which blood will be sampled for 3 hours. Afterwards, we will carry out a 30-minute interview about your experience using the mobile health application.

What you'll get for taking part

By taking part in this study, you will be making a valuable contribution to scientific knowledge and will help to pioneer this area of research.

close-up of a fitness watch

At the end of your participation, you will gain lifetime access to the ‘Metabolism’ app, which enables you to collect information on your physical activity, sleep and blood sugar from your wearable devices, and provides you with individualised lifestyle recommendations and education that can help build healthy habits.

You will also receive detailed feedback on your body composition, markers of metabolic health (e.g. blood sugar and cholesterol levels), physical activity levels and dietary intake. We will present your results alongside the recommended ranges (where possible) and explain what they mean.

For example, you will receive information on the following:

  • basal metabolic rate – How many calories your body burns at rest
  • activity energy expenditure – How many calories you burn through physical activity
  • body composition – How many kilograms of muscle and fat you have in your body
  • energy intake – How many calories you eat/drink per day
  • nutrient intake – How many grams of key nutrient to consume per day
  • blood sugar, fat and hormonal responses – How your body handles the nutrients you eat (i.e. sugar, fat)

Contact the lead researcher, Guoda Karoblyte, to sign up or ask questions.


Food image by Freepik

Blood sample image by Freepik