Condition category
Nutritional, Metabolic, Endocrine
Date applied
Date assigned
Last edited
Prospectively registered
Overall trial status
Recruitment status
No longer recruiting

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

Trial website

Contact information



Primary contact

Dr Nerys Astbury


Contact details

Nuffield Department of Primary Care Health Sciences
New Radcliffe House
Radcliffe Observatory Quarter
Woodstock Road
United Kingdom
+44 (0)18656 17958

Additional identifiers

EudraCT number number

Protocol/serial number


Study information

Scientific title

A randomised controlled trial of a low energy liquid diet treatment compared with usual care for weight management in primary care



Study hypothesis

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?

Ethics approval

We intend to apply for ethical approval in April to South Central - Oxford B ethics committee.

Study design

Open individually randomised two-arm parallel group study

Primary study design


Secondary study design

Randomised controlled trial

Trial setting

GP practices

Trial type


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

Intervention type



Drug names

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


Reason abandoned


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

Participant type


Age group




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.
11. Porphyria
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

United Kingdom

Trial participating centre

Oxfordshire Clinical Commissioning Group
Jubilee House, John Smith Drive Oxford Business Park South
United Kingdom

Sponsor information


University of Oxford

Sponsor details

Research Services
University of Oxford
Joint Research Office
Block 60
Churchill hospital
United Kingdom

Sponsor type




Funder type


Funder name

Cambridge Weight Plan Ltd (UK)

Alternative name(s)

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

Publication summary

Publication citations

Additional files

Editorial Notes