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Doctor Referral of Overweight People to Low Energy total diet replacement Treatment (DROPLET): pragmatic randomised controlled trial

BMJ 2018; 362 doi: (Published 26 September 2018) Cite this as: BMJ 2018;362:k3760

Linked BMJ opinion

Interventions to treat obesity work—so why am I not celebrating?

  1. Nerys M Astbury, senior researcher,
  2. Paul Aveyard, professor,
  3. Alecia Nickless, clinical trial statistician,
  4. Kathryn Hood, research assistant,
  5. Kate Corfield, clinical trial administrator,
  6. Rebecca Lowe, research assistant,
  7. Susan A Jebb, professor
  1. Nuffield Department of Primary Care Health Sciences, University of Oxford, UK
  1. Correspondence to: NM Astbury nerys.astbury{at}
  • Accepted 3 August 2018


Objective To test the effectiveness and safety of a total diet replacement (TDR) programme for routine treatment of obesity in a primary care setting.

Design Pragmatic, two arm, parallel group, open label, individually randomised controlled trial.

Setting 10 primary care practices in Oxfordshire, UK.

Participants 278 adults who were obese and seeking support to lose weight: 138 were assigned to the TDR programme and 140 to usual care. 73% of participants were re-measured at 12 months.

Interventions The TDR programme comprised weekly behavioural support for 12 weeks and monthly support for three months, with formula food products providing 810 kcal/day (3389 kJ/day) as the sole food during the first eight weeks followed by reintroduction of food. Usual care comprised behavioural support for weight loss from a practice nurse and a diet programme with modest energy restriction.

Main outcome measures The primary outcome was weight change at 12 months analysed as intention to treat with mixed effects models. Secondary outcomes included biomarkers of cardiovascular and metabolic risk. Adverse events were recorded.

Results Participants in the TDR group lost more weight (−10.7 kg) than those in the usual care group (−3.1 kg): adjusted mean difference −7.2 kg (95% confidence interval −9.4 to −4.9 kg). 45% of participants in the TDR group and 15% in the usual care group experienced weight losses of 10% or more. The TDR group showed greater improvements in biomarkers of cardiovascular and metabolic risk than the usual care group. 11% of participants in the TDR group and 12% in the usual care group experienced adverse events of moderate or greater severity.

Conclusions Compared with regular weight loss support from a practice nurse, a programme of weekly behavioural support and total diet replacement providing 810 kcal/day seems to be tolerable, and leads to substantially greater weight loss and greater improvements in the risk of cardiometabolic disease.

Trial registration International Standard Randomised Controlled Trials No ISRCTN75092026.


  • Contributors: SAJ and PA designed the study, NA was the trial manager and AN was the trial statistician. NA, KH, KC and RL were responsible for data collection. SAJ and NA drafted the paper and all authors contributed to the interpretation of the data and critical review of the paper.

  • Funding: This study was supported through a research grant from Cambridge Weight Plan UK to the University of Oxford and also supported by the National Institute for Health Research (NIHR) Collaboration for Leadership in Applied Health Research and Care Oxford at Oxford Health NHS Foundation Trust. SAJ, PA, and NA are supported by the Oxford NIHR Biomedical Research Centre and NIHR Collaboration for Leadership in Applied Health Research and Care Oxford at Oxford Health NHS Foundation Trust. The study was conducted and analysed in collaboration with an NIHR accredited clinical trials unit. All authors had access to all data after the statistical analysis was complete. The funders had no access to the data. SAJ had final responsibility for submission for publication. The investigators have no personal financial relationships with the funder. The funders had no role in study design, data collection, data analysis, data interpretation, or writing of the report. The views are those expressed by the authors and not necessarily those of the NHS, NIHR, or Department of Health. The University of Oxford holds the relevant clinical trials insurance policy for this study and acted as the study sponsor.

  • Competing interests: All authors have completed the ICMJE uniform disclosure form at and declare: the trial was in part funded by Cambridge Weight Plan UK but the authors receive no personal financial benefit. The study was an investigator initiated protocol and the funder had no access to the data. The investigators had an independent right to publish the results of the trial regardless of outcome. PA and SAJ have previously conducted studies in which weight loss interventions were provided to the NHS by WeightWatchers, Slimming World, or Rosemary Conley.

  • Ethical approval: This trial was approved by South Central Oxford B NHS Research Ethics Service Committee (NHS REC No 15/SC/0337).

  • Data sharing: Requests for access to data from the DROPLET study should be addressed to the chief investigator at All the individual participant data collected, after deidentification (including the data dictionary) will be available on request following publication. All proposals requesting data access will need to complete a data request form with details of the research question and analysis plan. All proposals will require the approval of the investigator team before any data are released.

  • Transparency: The guarantor (SAJ) affirms that the manuscript is an honest, accurate, and transparent account of the study bring reported; that no important aspects of the study have been omitted; and that any discrepancies from the study as planned (and, if relevant, registered) have been explained.

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