Cookies on this website

We use cookies to ensure that we give you the best experience on our website. If you click 'Accept all cookies' we'll assume that you are happy to receive all cookies and you won't see this message again. If you click 'Reject all non-essential cookies' only necessary cookies providing core functionality such as security, network management, and accessibility will be enabled. Click 'Find out more' for information on how to change your cookie settings.

Accept all cookies Reject all non-essential cookies Find out more

The Online Weight Loss Study

Testing the short-term effectiveness of Online Weight loss programmes


The OWL study is now closed to recruitment

Thank you for your interest in taking part in the OWL study.

We have now recruited all the participants we needed for this study.

So, unfortunately, it is not possible for you to take part.

We hope you will consider taking part in other research studies in the future.



If you like to know the results of the OWL study, please click on 'Plain English Summary OWL Results' for the plain English summary. The full paper can be found here.

Plain English Summary OWL Results

One of the best ways to improve your overall health is to lose at least 5% of your body weight, and weight loss programmes can help. But for some people, attending a regular weight-loss group can be a challenge.

Online weight loss programmes could provide a more convenient option – enabling you to access support from the comfort of your own home, in your own time.  

Are you interested in joining the Online Weight Loss Study?

We are a group of researchers at the University of Oxford and have started a new research study to look into three well-known online weight loss programmes to see how effective they can be in helping people to kick-start their weight loss.

We are looking for people with a BMI of 30 or more, who are not already taking part in a weight loss programme, to join this study.

Who is eligible to take part?

To take part, you should

  • be aged 18 years or above
  • have a Body Mass Index of 30kg/m2 or more (what is my BMI?)
  • have access to a mobile phone, the internet and a set of weighing scales
  • not be pregnant, breastfeeding, or planning to become pregnant during the course of the programme
  • not already be following a weight-loss programme

What is involved

Participants will be allocated randomly to one of four groups, three of which will be provided with access to an online weight loss programme for eight weeks.

After eight weeks, all participants will be asked to report their weight and complete a short questionnaire.

As a thank you for completing the study, they will receive a £10 voucher for taking part.

Frequently asked questions

Why have I had a letter inviting me to take part in the OWL study?

Your GP practice is one of those that have decided to take part in this study. The OWL researchers at the University of Oxford have NOT had access to your contact information or your medical records.

You have been invited to take part in the study because the information on your medical record indicates that you fulfil the inclusion criteria and are eligible to take part in the study. It is now up to you to decide whether you are interested in taking part in the study.

How do I enrol on the study?

If you are interested in taking part in this study, please follow the Participant information and eligibility link. This link will take you through the steps required to enrol yourself on to the OWL study.

Can both my husband and I take part?

Due to the random allocation it is very likely that you will be enrolled in two different groups, which we would not reccommend as it makes it more difficult for you to follow. But what you could do is for just one of you to enrol to the study and you can then both follow the allocated group together.

You're enrolled in the control group. What does that mean?

This study aims to find out whether online programmes help people to lose weight. If they work, we will compare weight loss between people who follow an online programme with weight loss and people who follow their normal routine. 

If you have been assigned to the control group, you might wonder what this means. It tells you that you should continue your normal routine. 

You may feel let-down because you are not getting the chance to try one of the online programmes on offer. But it is important for the study that you follow the instructions by continuing with your normal routine. Your contribution is valuable for the study and we appreciate that you are taking part.

get involved

How to enrol

Please click the following link to read the details in our participant information sheet and to access the eligibility questionnaire.

The study team

There are no team members found
There are no team members found

OWL study protocol version 3.1, 02/10/2019

The OWL study protocol

OWL: Testing the short-term effectiveness of Online Weight loss programmes

Funder: NIHR Oxford Biomedical Research Centre

Sponsor: University of Oxford

owl@phc.ox.ac.uk

This trial has been approved by the South Central - Oxford A Research Ethics Committee, reference: 19/SC/0210