Plain English Summary
Background and study aims
Around 1 in 4 people in the UK are seriously overweight (obese). Being obese makes it more likely that a person will develop diabetes, heart disease and some types of cancer. Extra body weight also puts a strain on muscles and joints, making it difficult and sometimes painful to move around. Together, these factors increase the likelihood that people who are overweight will experience poor health and a reduced quality of life. At the moment, doctors and nurses in primary care support people to lose weight by referring patients to a commercial weight loss provider offering support in a group setting, such as Weight Watchers. But weight loss in a group setting does not suit everybody. Another alternative available is low-energy liquid diets. Low-energy liquid diets have been used to help people lose weight for many years and there are a number of companies who provide liquid diet products together with individual advice and support. Low-energy liquid diets usually provide a person with around 800 calories a day, mostly in the form of specially prepared drinks. The diet has all the vitamins and minerals that are essential for good health, but a lot less calories than most people eat on a regular weight loss diet. This means that liquid diets usually lead to faster weight loss, especially in the early weeks. However, it is not known whether low-energy liquid diets are effective at helping people maintain weight loss a year or more later. The aim of this study, the DROPLET study, is to test whether GPs referring patients who are obese to a low-energy liquid diet, in this case the Cambridge Weight Plan, can help people to lose more weight than a weight loss programme provided by the GP practice nurse. The weight loss of participants in both groups will be measured over 1 year.
Who can participate?
Adults diagnosed as obese.
What does the study involve?
Participants are randomly allocated into one of two groups. Those in group 1 (intervention group) are put on a low energy liquid diet plan by their GP. Those in group 2 (control group) are given standard care for weight management by their GP. Participants visit their GP practice at the start of the study, and then again 4, 12, 26 and 52 weeks later to see a GP, nurse or a member of the research team for follow up. Participants also speak to the study team over the phone at 4, 8 and 12 weeks into the study. Participants who lose a lot of weight during the trial may be invited to a follow up interview 1 year later to see whether they are able to keep the weight off. Blood samples are taken at the start of the study, and again after 1 year, to see if there is any change in blood markers, such as cholesterol and insulin. This is to assess participants’ risk of developing heart disease or diabetes. Participants also complete questionnaires at the end of the trial.
What are the possible benefits and risks of participating?
Everyone who takes part in the trial should benefit as both groups will receive support to help them to lose weight.
Where is the study run from?
Oxfordshire Clinical Commissioning Group (UK)
When is the study starting and how long is it expected to run for?
January 2015 to January 2018
Who is funding the study?
Cambridge Weight Plan Ltd (UK)
Who is the main contact?
Dr N Astbury
Dr Nerys Astbury
Nuffield Department of Primary Care Health Sciences
New Radcliffe House
Radcliffe Observatory Quarter
+44 (0)18656 17958
A randomised controlled trial of a low energy liquid diet treatment compared with usual care for weight management in primary care
Does a GP referral of obese adults to a low energy liquid diet treatment result in a larger reduced weight change after 52 weeks than usual care for weight management in primary care?
We intend to apply for ethical approval in April to South Central - Oxford B ethics committee.
Open individually randomised two-arm parallel group study
Primary study design
Secondary study design
Randomised controlled trial
Patient information sheet
Not available in web format, please use contact details to request a participant information sheet.
Obesity in adults
Participants are allocated to one of two groups:
1. GP referral to a low energy liquid diet treatment
2. Standard care for weight management offered by primary care providers
Primary outcome measures
Change in mean body weight from baseline to 52 weeks.
Secondary outcome measures
1. Change in mean weight between baseline, 12 and 26 weeks.
2. Change in mean fat mass between baseline and 12, 26 and 52 weeks.
3. Change in mean low-density lipoprotein (LDL) cholesterol between baseline and 52 weeks
4. Change in mean HOMA IR (insulin resistance) between baseline and 52 weeks
5. Change in mean systolic and diastolic blood pressure between baseline and 12 weeks, 26 weeks and 52 weeks.
6. Change in the SF-12 physical functioning scale between baseline and 52 weeks
Overall trial start date
Overall trial end date
Participant inclusion criteria
1. Participant is willing and able to give informed consent for participation in the study
2. Male or female, 18 years and older.
3. Body Mass Index ≥30 kg/m2
4. Likely to benefit from weight loss in the GP’s opinion
Target number of participants
Participant exclusion criteria
1. Unable to understand English
2. Currently or recently (within 3 months of study entry) attended a weight management programme, currently participating in another weight loss study or ever had bariatric surgery.
3. Breastfeeding, pregnant or planning to become pregnant during the course of the study.
4. Receiving insulin therapy
5. Heart attack or stroke within the last 3 months, heart failure of grade II New York Heart Association and more severe, or prolonged QT syndrome.
6. MAOI medication
7. Chronic renal failure of stage 4 or 5
8. Active liver disease except fatty liver or anyone with a past history of hepatoma or within 6 months of onset of acute hepatitis.
9. People having active treatment for cancer other than skin cancer treated with curative intent by local treatment only, or people taking hormonal or other long-term secondary prevention treatment after initial cancer treatment.
10. Active treatment or investigation for possible or confirmed gastric or duodenal ulcer. Maintenance treatment with acid-suppression is not a contraindication.
12. Scheduled or on a waiting list for surgery within 1 year
13. Any member of household is already enrolled in the study
14. Unwilling to provide blood samples
15. Patients that the GP judges not able to meet the demands of either treatment programme or measurement schedule. This may include severe medical problems not listed above or severe psychiatric problems including substance misuse that make following the treatment programme or adhering to the protocol unlikely.
Recruitment start date
Recruitment end date
Countries of recruitment
Trial participating centre
Oxfordshire Clinical Commissioning Group
Jubilee House, John Smith Drive Oxford Business Park South
Cambridge Weight Plan Ltd (UK)
Funding Body Type
Funding Body Subtype
Results and Publications
Publication and dissemination plan
Not provided at time of registration
Intention to publish date
Participant level data
Not provided at time of registration
Results - basic reporting