Condition category
Mental and Behavioural Disorders
Date applied
Date assigned
Last edited
Prospectively registered
Overall trial status
Recruitment status
No longer recruiting

Plain English Summary

Not provided at time of registration

Trial website

Contact information



Primary contact

Dr Deborah Lycett


Contact details

Primary Care Clinical Sciences School of Health and Population Sciences
B15 2TT
United Kingdom

Additional identifiers

EudraCT number number

Protocol/serial number


Study information

Scientific title

Slimming World in Stop Smoking Services (SWISSS)



Study hypothesis

Quitting smokers gain weight which puts some off attempting to quit, and seems to increase the risk of developing type 2 diabetes. Dieting is the main way to control weight but may worsen cigarette cravings and undermine cessation. A review of trials showed general healthy eating education does not reduce weight gain in quitting smokers and may hamper smoking cessation. However, planning diets to meet individual requirements, setting and reviewing weight targets does reduce weight gain; but whether this reduces the chance of successfully quitting is uncertain.

Commercial weight management programmes (CWMPs) provide this type of individual dietary support and are available on prescription in most primary care trusts. Clinical trials show CWMPs lead to greater weight loss than other primary care interventions or dieting without support. The aim of this trial is to assess whether referral to a CWMP reduces weight gain on smoking cessation. If so, this would lead to a necessary much larger trial to see whether it did so at the expense of successfully quitting smoking.

We will recruit patients from NHS stop smoking services, they must be smokers over 18 without any condition in which weight loss would be harmful. They will be randomised to either a CWMP during their quit attempt or usual care. All will receive usual stop smoking support and be weighed at the start, end of treatment and at six month follow-up.

Ethics approval

First MREC, 29 June 2012 ref:12/SW/0159

Study design

Randomised interventional phase II trial

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 the contact details below to request a patient information sheet


Smoking and weight loss


This will be the withdrawal orientated behavioural support provided by NHS stop smoking services which increase the chance of a successful quit attempt four-fold (West, 2010). This consists of weekly behavioural support typically for two weeks before and until four weeks after quit day focusing on key behavioural change techniques and nicotine replacement, varenicline, or bupropion are given to relieve withdrawal symptoms. Participants are encouraged to quit smoking first, before tackling weight; Usual care plus Slimming World, In addition to usual care, participants will be given a referral voucher for Slimming World when they attend their pre-quit visit. They will be booked in to attend weight management sessions from their quit day (or as near to that date as possible). They will attend SW for 12 weeks receiving support to lose or prevent weight gain. The choice of modest weight loss or weight gain prevention will depend upon whether an individual wants to lose weight or not and whether or not s/he is overweight or ; Follow Up Length: 5 month(s); Study Entry : Single Randomisation only

Intervention type



Phase II

Drug names

Primary outcome measures

Change in weight from baseline (one week before quit date) to twelve weeks

Secondary outcome measures

No secondary outcome measures

Overall trial start date


Overall trial end date


Reason abandoned


Participant inclusion criteria

1. Daily smokers with expired CO >10ppm
2. Aged 18 or over
3. Willing to be randomised to either the control or intervention arm and willing and able to comply with the intervention and all study procedures
4. Male & female participants

Participant type


Age group




Target number of participants

UK Sample Size: 320; Description: We will recruit 320 participants, 160 in each arm. With an alpha error rate of 5% and 90% power this will detect a 2kg (SD=2.5)

Participant exclusion criteria

1. Pregnant smokers
2. BMI<23 kg/m2. Mortality has been shown to be lowest in those with a 22>BMI<25 (Prospective studies collaboration, 2009) so preventing weight gain in those with lower BMIs is may not lead to health gain
3. Any medical condition in which weight loss would be contraindicated e.g. current course of chemotherapy

Recruitment start date


Recruitment end date



Countries of recruitment

United Kingdom

Trial participating centre

Primary Care Clinical Sciences School of Health and Population Sciences, Edgbaston
B15 2TT
United Kingdom

Sponsor information


University of Birmingham (UK)

Sponsor details

Behavioural Brain Sciences Centre
B15 2TT
United Kingdom

Sponsor type




Funder type


Funder name

National Institute of Health Research [NIHR] - National School for Primary Care Research (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

1. 2013 protocol in

Publication citations

  1. Protocol

    Lycett D, Aveyard P, Farmer A, Lewis A, Munafò M, Slimming World in Stop Smoking Services (SWISSS): study protocol for a randomized controlled trial., Trials, 2013, 14, 182, doi: 10.1186/1745-6215-14-182.

Additional files

Editorial Notes