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Take part in our study exploring how glycogen use affects gut hormones and appetite

Volunteer in our study to help further our understanding of using fat or carbohydrate as fuel during exercise.

Background information

Find out more about our study.

We are currently recruiting for a randomised control trial to investigate the effect of using fat or carbohydrate as fuel during exercise on certain blood markers and appetite. Research in this area has shown people who exercise frequently are better at regulating food intake. We would like to know if whether the type of fuel used during the exercise has an influence on how much you eat. Furthermore, we will investigate if there are differences between men and women.

Study information

We will be recruiting for this study until Spring 2024, or until we reach capacity.

What's involved in the study

The study will involve visiting the university on 4 occasions. There will be 1 preliminary testing day and 3 main trial days where you will exercise for 1 hour after being given a high-carbohydrate drink, vitamin B3 or a placebo and will have blood and muscle samples taken.

Preliminary visit:

This will last approximately 2 hours, we will take some measures of body composition and you will perform a short (approximately 24 minutes) sub-maximal exercise test on a stationary bike.

Main trial days:

These will last for approximately 5 hours. You will have blood samples and a muscle biopsy (optional) taken before and after 1 hour of exercise. You will be given either a carbohydrate drink, vitamin B3 or a placebo to take at various time points. You will then be provided with a lunch in which we will assess how much you eat.


We are looking for women who meet the following criteria:

  • Aged 18 to 60 years old and in general good health. Women must be premenopausal
  • Have a BMI between 18 and 30 kg∙m-2
  • Be physically active and perform at least 30 minutes of exercise 3 times a week

Exclusion criteria

  • Weight instability (>5kg change in body mass over last 6 months)
  • Being a restrained eater (e.g. limiting food intake, calorie counting)
  • Current smoker
  • Aversion or allergy to test meal foods
  • pregnant or lactating
  • Amenorrhoea in women (absence of a menstrual period)
  • Any medical condition or medication that could introduce bias into the study (e.g. diabetes, CVD, lipid or glucose metabolism altering medications)
  • Any cardiopulmonary condition prohibiting exercise testing
  • Any contraindication to vitamin B3 or aspirin (e.g., diabetes, gout, clotting disorders, allergy to non-steroidal anti-inflammatory drugs)
  • Sleeping disorders such as snoring or sleep apnoea

What you'll get for taking part

The main benefit of taking part is that you will be provided with detailed feedback on your physiological health. This will include details about your fitness level and metabolic rate, body composition and BMI, and blood markers and hormones. You will also be making an invaluable contribution to scientific knowledge that will pioneer new findings in this area of research.


All identifiable data will be kept in a locked cabinet or in a password protected spreadsheet on the university server. For this reason, only the lead investigator and principal supervisor will have access to this. As a participant you will have access to your own data upon request.1

We'd love for you to be involved.

Take part in our research

Contact us

If you have any questions about this research study, please contact the lead researcher.

1 The study has been approved by Bristol Research Ethics Committee (ref 22/SW/0062).