Published 14th February 2024

Information Sheet: Opting in to ZOE’s Intermittent Fasting Study

Written byZOE Health Study

    Why is ZOE studying Intermittent Fasting?

    We, ZOE, in collaboration with King’s College London, hope to understand the effect of Intermittent Fasting, specifically Time Restricted Eating, on various outcomes of health. We want to understand how this eating behaviour affects your levels of hunger, mood, energy, body weight and symptoms already reported in the Health Study App. 

    The Intermittent Fasting Study has been launched as a sub-study within the ZOE Health Study. You should read through this information sheet and provide your consent to participate before you can take part. 

    Why have I been invited to participate?

    We are asking you to take part in this study because you are currently a participant in the ZOE Health Study. 

    You must be able to fast for the stated period in this study (14 hours per day) and to do so safely. If you have any concerns about this study and how if affects your health, you should consult your healthcare provider about whether this study is right for you.

    How long will I take part in this research study?

    This study takes 3 weeks to complete. You have the option to extend your study duration beyond this time.

    What will happen if I take part?

    You will be asked to complete a dietary questionnaire before you start the study.

    For the first week of the study, you will be asked to follow your normal eating behaviour and report in the Health Study App the exact time when you start/finish eating or drinking each day. Alongside this you will be asked to record your mood, energy, hunger, body weight (optional) and health symptoms, on a daily basis. You may also be asked to log your food and drink using a food diary.

    For the second and third weeks of the study, you will be asked to repeat the daily tasks from the first week. However, for these weeks you will be asked to fit all your food and drink (except for water) into a 10 hour period. This means that you can start to eat and drink when you like during the day, but that you should finish eating and drinking on that day no later than 10 hours after the start time. 

    For example, if you start eating at 8 AM, you should stop eating at 6 PM on that day. This forms a 10 hour ‘eating window’. 

    You may choose to continue to follow the modified eating behaviour beyond the second and third study weeks. This is entirely optional. You may also choose to shorten your eating window to less than 10 hours. However, you should not shorten the eating window to 6 hours or less.

    This behaviour modification is for research purposes only, and does not have a medical purpose. The Health Study App is not intended as a medical device and you will not receive treatment based on your reports.

    Participation in this study is optional, and you can withdraw at any time. It is up to you how much or little you wish to contribute.

    Do I have to take part?

    Participation is completely voluntary. You should only take part if you want to and choosing not to take part will not disadvantage you in any way. Once you have read this information sheet, please contact us if you have any questions that will help you make a decision about taking part. If you decide to take part we will ask you to indicate your consent through the app and you will be given a copy of this information sheet to keep.

    What are the possible benefits from taking part?

    There are potential benefits to participating in the Intermittent Fasting Study. Provided you complete the study, your study results will be shared with you. These will include how you personally responded to the 10 hour eating window while on the study in terms of the health outcomes you logged, including hunger, mood, energy, and symptom burden.

    What are the possible risks of taking part?

    We do not expect you to experience any serious side effects while taking part in this study. However, you should speak to your healthcare provider if you are concerned about your health being impacted by this study. In particular, the fasting involved in this study may affect the following groups: people suffering from diabetes; people that have a history of eating disorders; those that have an uncontrolled chronic medical condition; those medicating with insulin; those medicating with sulphonylureas; those medicating with meglitinides. Individuals in these groups are encouraged to speak with their doctors before consenting to this study.

    If at any point while on the study you start to feel unwell as a result of fasting, you should stop fasting and consult your healthcare provider.

    How will ZOE share the findings of research?

    ZOE will display or provide links to key research findings in the app, share them through webinars, and produce informative blogs. 

    ZOE and KCL will publish detailed results in preprints and peer-reviewed scientific papers and present them at scientific conferences so others in the research community can learn from what we have found. 

    How will ZOE use my data?

    ZOE will never sell your data. 

    When we share data with anyone, information such as name, address and email address will be removed. We will delete your data at any time on request.

    Read our privacy policy to find out more about how we collect and use data.

    What else will ZOE do with my data?

    ZOE is a commercial company that develops data science tools to help understand health. 

    In the future, ZOE may develop commercial products using data and insights from this study. This is needed to sustain the tools, technology and personnel that are needed to carry out our work for the long term.

    Any commercial product will always be based on combined data or the summary results of our analyses and will not contain any individual’s data.

    More details on this in our privacy notice under Research Studies.

    How can I opt out or withdraw from ZOE research?

    Taking part in this study is entirely optional. You can opt-out after signing up if you change your mind about participating. You can email if you would like to stop receiving study invitations.

    If you would like to delete all your Intermittent Study information, you should email We will remove all data from this study within 14 days. 

    Who should I contact for further information?

    If you have any questions about the app itself or how we collect and manage your data before sharing for the purposes of research, please contact ZOE at

    You can also contact the study team at

    What if I have further questions, or if something goes wrong?

    If this study has harmed you in any way or if you wish to make a complaint about the conduct of the study you can contact King's College London using the details below for further advice and information: 

    The Chair, Biomedical & Health Sciences, Dentistry, Medicine and Natural & Mathematical Sciences (BMD) Research Ethics Panel –

    Thank you for reading this information sheet and for considering taking part in this research.