A Lloyd

A-M Glenny

AL Ahern

Amanda Avery

Carolyn Pallister

David Johnathan Brogelli

DL Streiner

H Truby

J Poulter

J Stubbs

Jacquie Lavin

Jenny Barber

JH Lavin

K Jolly

National Institute for Health and Clinical Excellence

Richard James Stubbs

RJ Stubbs

SA Jebb

Stephen Whybrow

BMC Research Notes

English

PubMed

Stubbs, Richard James

Brogelli, David Johnathan

Barber, Jenny

Pallister, Carolyn

Whybrow, Stephen

Avery, Amanda

Lavin, Jacquie

The Open University

Stubbs et al. BMC Research Notes 2013, 6:161http://www.biomedcentral.com/1756-0500/6/161SHORT REPORT Open AccessService evaluation of weight outcomes as afunction of initial BMI in 34,271 adults referred toa primary care/commercial weight managementpartnership schemeRichard James Stubbs1,2*, David Johnathan Brogelli1, Jenny Barber1, Carolyn Pallister1, Stephen Whybrow3,Amanda Avery1 and Jacquie Lavin1AbstractBackground: It is not clear if behaviour change programmes are more or less effective for weight management inpeople with high BMIs than for those who are moderately overweight. An earlier service evaluation reported on therate and extent of weight loss in a primary care/commercial weight management organisation partnership scheme,in 34,271 patients were referred by their health care professionals to a UK commercial weight managementorganisation, Slimming World for 12 weekly sessions. This project updated that service evaluation by examiningweight loss outcomes as a function of initial BMI in the same 34,271 patients.Findings: Patients referred to the scheme (n = 34,271) were categorised by BMI groups <30 kg/m2, 30-34.9 kg/m2,35-39.9 kg/m2 and to ≥ 40 kg/m2. Mean weight losses after 12 weekly sessions were 2.9, 3.6, 4.1, and 4.8 kg for eachBMI category respectively. Regression analysis showed that after adjusting for age and gender, relative to the <30 kg/m2 group, absolute weight losses were 0.8, 1.4 and 2.4 kg more for the 30-34.9 kg/m2, 35-39.9 kg/m2 and to ≥ 40 kg/m2 groups, respectively (all p<0.001). Percent weight loss was similar in each BMI category: 3.7%, 4.0%, 4.0% and 3.9%,respectively (p<0.001).Conclusions: This service evaluation demonstrates that 12 week referral to a commercial organisation is as effective forpeople with high BMIs as for those who are moderately overweight.Keywords: Obesity, Treatment, Weight management, Body mass index, Weight outcomesBackgroundIn a previous paper we have examined the rate and extentof weight loss in a primary care/commercial weightmanagement organisation (CWMO) partnership scheme(called Slimming on Referral). In that paper 34,271 patientswere referred by their health care professionals to a UKcommercial weight management organisation, SlimmingWorld, for 12 weekly sessions [1]. Data were reported forthe whole population, for completers (those who attended10 of 12 sessions) versus non-completers, and for men andwomen [1]. There is now a growing body of data* Correspondence: james.stubbs@slimming-world.com1Nutrition and Research Department, Slimming World, Clover Nook Road,Somercotes, Alfreton, Derbyshire DE55 4RF, UK2University of Derby, Kedleston road, Derby, Derbyshire DE22 1GB, UKFull list of author information is available at the end of the article© 2013 Stubbs et al.; licensee BioMed CentralCommons Attribution License (http://creativecreproduction in any medium, provided the orsuggesting that commercial diet and lifestyle programmesare effective in the general population [1-8]. However, it isnot clear from current published studies whether lifestyleinterventions are as effective in patients with higher BMIsthan for those who are moderately overweight [1,2].The purpose of the current analysis was to examinethe effectiveness of a primary care/CWMO partnershipscheme in patients of different BMI categories. Data werecollected from participants in the slimming on referralscheme between May 2004 and November 2009, who hadtime to finish their full 12-week referral. This resulted inthe inclusion of 38,614 patients who were referred fromwithin 77 Primary care Trusts or NHS Trusts, for whomdata on weight, height, age and gender were collected. Ofthese there were 2,625 cases where the data for one orLtd. This is an Open Access article distributed under the terms of the Creativeommons.org/licenses/by/2.0), which permits unrestricted use, distribution, andiginal work is properly cited.Table 1 Patient characteristics at week 1 of the referral scheme and weight change by start BMI categoryBMI < 30 kg/m2 BMI 30–34.9 kg/m2 BMI 35–39.9 kg/m2 BMI ≥ 40 kg/m2Total n=3697 Total n=11759 Total n=9902 Total n=8913Mean SD Mean SD Mean SD Mean SD f-value p-valueHeight (m) 1.65 0.08 1.64 0.08 1.64 0.08 1.64 0.08 48.60 <0.001Weight (kg) 76.8 8.0 88.0 9.6 100.8 10.9 122.3 18.6 19885.38 <0.001Age (years) 48.1 15.0 48.1 14.8 47.2 14.6 45.8 13.4 64.43 <0.001Weight change (kg) −2.9 2.8 −3.6 3.2 −4.1 3.7 −4.8 4.4 346.58 <0.001Percent weight change −3.7 3.6 −4.0 3.6 −4.0 3.6 −3.9 3.5 7.06 <0.001Weeks attended 8.7 3.6 8.9 3.5 8.8 3.6 8.9 3.5 0.19 0.905Start BMI (kg/m2) 28.2 1.4 32.5 1.4 37.3 1.4 45.4 5.2 44536.13 <0.001End BMI (kg/m2) 27.2 1.7 31.2 1.8 35.8 1.9 43.6 5.3 37989.02 <0.001BMI change (kg/m2) −1.1 1.0 −1.3 1.2 −1.5 1.3 −1.8 1.6 387.75 <0.001Proportion achieving 5% Weight loss 33.4% 36.6% 36.4% 35.8% 4.10 0.006Proportion achieving 10% Weight loss 5.5% 6.1% 6.2% 5.4% 3.69 0.011Stubbs et al. BMC Research Notes 2013, 6:161 Page 2 of 4http://www.biomedcentral.com/1756-0500/6/161more of the 12 referral vouchers issued per participant wasunclear or could not be resolved (spoiled vouchers, illegiblewriting etc.) and 1,718 cases where the participant com-pleted the scheme outside of the 14 (12 plus 2) week timewindow, due to circumstances such as bereavement or ill-ness. This left 34,271 in the present study. 80 participantswere included in the database but there was no data fortheir date of birth. Age data are reported excluding thesesubjects. Some participants went on to self-fund further at-tendance following the initial 12-week referral and otherswere offered subsequent 12-week referral packages fromtheir health care team. Results for the latter are reportedelsewhere [9]. The data in this analysis covers the initial12-week sessions of the referral scheme.Data for this service evaluation was collected as part ofroutine data collection within the referral programme. Atthe point of referral patients’ gender, date of birth andheight were recorded by the health professional. When thepatient enrolled at the weight management group (week 1of the referral), their start weight and date were recorded.Each week the patient returned to group their weightchange was recorded along with date of attendance. Thesame calibrated scales were used each week at a givengroup to record weight and weight change. The collecteddata were sent to the research team for input into the refer-ral database.This work is categorised as a service evaluation under theAd Hoc Advisory Group on the Operation of NHS Re-search Ethics Committees, guidelines (2006). Existing datawere anonymised and analysed as an intervention in useonly to ask the question "What standard does this ser-vice achieve?"Data were extracted from the referral database, andsubjected to a number of parameter checks for outliers,and anomalous data entry. Anomalies were checked againstthe raw source data to resolve any issues that arose. Fromthe raw data collected, start BMI, end BMI, BMI change,weight change and percent weight change were calculated.There was considerable variability in the number of ses-sions attended, ranging from 1–12 weeks. Mean attendancewas 8.9 of 12 sessions.The end weight was calculated based on the members’last attendance at group during the referral period usingthe Last Observation Carried Forward approach [10].For the current analysis weight loss outcomes wereanalysed by the BMI categories <30 kg/m2, 30–34.9 kg/m2,35–39.9 kg/m2 and ≥40 kg/m2. The effects of different fac-tors on weight loss between BMI categories were assessed,by fitting linear models and examining the significance offitted terms in these models, through regression and ana-lysis of variance. All analysis was performed using theGENSTAT 5 statistical program (Genstat 5 RothampsteadExperimental Station, Harpenden, UK). Results are ex-pressed as mean (SD).FindingsThe physical characteristics and weight outcomes by BMIcategory are given in Table 1. Eleven percent had a startBMI <30 kg/m2, 34% between 30–34.9 kg/m2, 29% be-tween 35–39.9 kg/m2 and 26% had a start BMI ≥40 kg/m2.Weight, end BMI, BMI change and absolute weight loss allincreased with increasing BMI category (all p<0.001). Ab-solute weight losses over the 12 week study period were2.9, 3.6, 4.1, and 4.8 kg for the BMI categories <30 kg/m2,30–34.9 kg/m2, 35–39.9 kg/m2 and ≥40 kg/m2, respect-ively. Regression analysis showed that after adjusting forage and gender, relative to the <30 kg/m2 group, absoluteweight losses were 0.8, 1.4 and 2.4 kg more for the 30–34.9kg/m2, 35–39.9 kg/m2 and ≥40 kg/m2, groups, respectively(all p<0.001). Percent weight loss was similar in each BMIStubbs et al. BMC Research Notes 2013, 6:161 Page 3 of 4http://www.biomedcentral.com/1756-0500/6/161category at 3.7, 4.0, 4.0 and 3.9% for BMI categories <30kg/m2, 30–34.9 kg/m2, 35–39.9 kg/m2 and ≥40 kg/m2.Regression analysis showed that after adjusting for age andgender, relative to the <30 kg/m2 group, percent weightlosses were 0.3, 0.3 and 0.2% greater for the 30–34.9 kg/m2, 35–39.9 kg/m2 and ≥40 kg/m2 groups, respectively(all p<0.001). For each BMI category those achieving 5%weight loss were 33, 37, 36 and 36%, respectively (maineffect, p=0.006). Regression analysis showed that significantdifferences occurred between the BMI categories <30 kg/m2 and 30–34.9 kg/m2 (p=0.028). The percentage of thoselosing 10% in their first 12 sessions by BMI category were6, 6, 6 and 5% respectively (main effect, p=0.011). Specificgroup differences were not significant in regression com-parisons. There was no significant difference in the numberof weeks attended as a function of BMI category (p=0.905).The current analysis illustrates that percent weight losswas consistent across the BMI range and that those withBMIs ≥40 (who represented 26% of participants referredfrom primary care) lost a similar percentage of their initialbody weight as other participants at a lower BMI. In thepresent service evaluation, participants followed a groupsupport programme and dietary plan, which is structuredaround ad libitum intake of low energy dense foods, prin-ciples of energy balance and appetite regulation to reduceenergy intake, with additional guidance to ensure a ba-lanced diet [11]. The present data set suggests that partici-pants with a BMI ≥40 can achieve higher absolute andsimilar percent weight losses to their counterparts at lowerBMIs when following a low energy density dietary plan,ad libitum.Average start BMI of the study population was in therange that would be recommended for more intensive in-terventions such as pharmacotherapy and for a significantpercentage, bariatric surgery [12,13]. Start BMI averaged36.8 kg/m2 and 26% of this referral population had aBMI ≥40 kg/m2. This suggests that lifestyle interventionscan work in populations with BMIs that are normallyrecommended to receive secondary or tertiary care.As this was a service evaluation, it was limited by theabsence of a control group and the fact that the resultswere based upon those people who joined a group, ra-ther than intention to treat. The study only observedweight changes over 12 weekly sessions and there wasno longer-term follow up. Key strengths were that thereferral programme evaluation assessed the effectivenessof the programme as it runs in real life, the sample sizewas large and conducted in members of the general pub-lic aiming to control their weight in their everyday lives.ConclusionReferral to a commercial organisation is as effective forpeople with high BMIs as for those who are lessoverweight and attendances were similar between BMIcategories.AbbreviationsCWMO: Commercial weight management organisation; SD: StandardDeviation; BMI: Body Mass Index; NHS: National Health Service.Competing interestsRJS, DJB, JB, CP, AA and JL work for Slimming World. SW was supported bySlimming World for the analysis and preparation of this manuscript.Authors’ contributionsJS, DB, JB, CP and SW collated the data, JS, CP, AA and JL were involved inthe design of the study, JS and SW were involved in the statistical analysis,JS, CP and DB drafted the manuscript. All authors read and approved thefinal manuscript.AcknowledgementWe are grateful to GW Horgan of Biomathematics and Statistics Scotland, forconducting an independent statistical analysis of the data. We would like tothank the Slimming World on Referral team for entry of the raw data andtheir general support to all primary care/commercial partnerships.FundingThe analysis of the data was funded by Slimming World.Author details1Nutrition and Research Department, Slimming World, Clover Nook Road,Somercotes, Alfreton, Derbyshire DE55 4RF, UK. 2University of Derby,Kedleston road, Derby, Derbyshire DE22 1GB, UK. 3Public Health NutritionResearch Group, University of Aberdeen, Aberdeen AB25 2ZD, UK.Received: 16 October 2012 Accepted: 22 April 2013Published: 24 April 2013References1. Stubbs RJ, Pallister C, Whybrow S, Avery A, Lavin JH: Weight outcomes for34,271 participants in a commercial/primary care weight managementpartnership scheme. Obes Facts 2011, 4:113–120.2. Ahern AL, Olson AD, Aston LM, Jebb SA: Weight watchers on prescription:an observational study of weight change among adults referred toweight watchers by the NHS. BMC Public Health 2011, 11:434.3. Jebb SA, Ahern AL, Olson AD, Aston LM, Holzapfel C, Stoll J, Amann-GassnerU, Simpson AE, Fuller NR, Pearson S, et al: Primary care referral to acommercial provider for weight loss treatment versus standard care: arandomised controlled trial. Lancet 2011, 378:1485–1492.4. Jolly K, Lewis A, Beach J, Denley J, Adab P, Deeks JJ, Daley A, Aveyard P:Comparison of range of commercial or primary care led weightreduction programmes with minimal intervention control for weight lossin obesity: lighten Up randomised controlled trial. BMJ 2011, 343:d6500.5. Lloyd A, Khan R: Evaluation of healthy choices: a commercial weight lossprogramme commissioned by the NHS. Perspect Public Health 2011,131:177–183.6. Poulter J, Hunt P: Weight change of participants in the weight watchersGP referral scheme. Int J Obes Relat Metab Disord 2008, 32:S233.7. Truby H, Baic S, deLooy A, Fox KR, Livingstone MB, Logan CM, MacdonaldIA, Morgan LM, Taylor MA, Millward DJ: Randomised controlled trial offour commercial weight loss programmes in the UK: initial findings fromthe BBC "diet trials". BMJ 2006, 332:1309–1314.8. Lavin JH, Avery A, Whitehead SM, Rees E, Parsons J, Bagnall T, Barth JH,Ruxton CHS: Feasibility and benefits of implementing a slimming onreferral service in primary care using a commercial weight managementpartner. Public Health 2006, 120:872–881.9. Stubbs J, Brogelli D, Pallister C, Whybrow S, Avery A, Lavin J: Attendanceand weight outcomes in 4,754 adults referred over six months to aprimary care/commercial weight management partnership scheme. ClinObes 2012, 2:6–14.10. Streiner DL: The case of the missing data: methods of dealing withdropouts and other research vagaries. Can J Psychiatry 2002, 47:68–75.11. Stubbs J, Whybrow S, Lavin JH: Dietary and lifestyle measures to enhancesatiety and weight control. Nutr Bull 2010, 35:113–125.Stubbs et al. BMC Research Notes 2013, 6:161 Page 4 of 4http://www.biomedcentral.com/1756-0500/6/16112. Glenny A-M, O'Meara S, Melville A, Sheldon TA, Wilson C: The treatmentand prevention of obesity: a systematic review of the literature. Int JObes 1997, 21:715–737.13. National Institute for Health and Clinical Excellence: Obesity: the prevention,identification, assessment and management of overweight and obesity inadults and children. London: Department of Health; 2006.doi:10.1186/1756-0500-6-161Cite this article as: Stubbs et al.: Service evaluation of weight outcomesas a function of initial BMI in 34,271 adults referred to a primary care/commercial weight management partnership scheme. BMC ResearchNotes 2013 6:161.Submit your next manuscript to BioMed Centraland take full advantage of: • Convenient online submission• Thorough peer review• No space constraints or color ﬁgure charges• Immediate publication on acceptance• Inclusion in PubMed, CAS, Scopus and Google Scholar• Research which is freely available for redistributionSubmit your manuscript at www.biomedcentral.com/submit

Service evaluation of weight outcomes as a function of initial BMI in 34,271 adults referred to a primary care/commercial weight management partnership scheme

Springer - Publisher Connector

Stubbs et al. BMC Research Notes 2013, 6:161
http://www.biomedcentral.com/1756-0500/6/161SHORT REPORT Open AccessService evaluation of weight outcomes as a
function of initial BMI in 34,271 adults referred to
a primary care/commercial weight management
partnership scheme
Richard James Stubbs1,2*, David Johnathan Brogelli1, Jenny Barber1, Carolyn Pallister1, Stephen Whybrow3,
Amanda Avery1 and Jacquie Lavin1Abstract
Background: It is not clear if behaviour change programmes are more or less effective for weight management in
people with high BMIs than for those who are moderately overweight. An earlier service evaluation reported on the
rate and extent of weight loss in a primary care/commercial weight management organisation partnership scheme,
in 34,271 patients were referred by their health care professionals to a UK commercial weight management
organisation, Slimming World for 12 weekly sessions. This project updated that service evaluation by examining
weight loss outcomes as a function of initial BMI in the same 34,271 patients.
Findings: Patients referred to the scheme (n = 34,271) were categorised by BMI groups <30 kg/m2, 30-34.9 kg/m2,
35-39.9 kg/m2 and to ≥ 40 kg/m2. Mean weight losses after 12 weekly sessions were 2.9, 3.6, 4.1, and 4.8 kg for each
BMI category respectively. Regression analysis showed that after adjusting for age and gender, relative to the <30 kg/
m2 group, absolute weight losses were 0.8, 1.4 and 2.4 kg more for the 30-34.9 kg/m2, 35-39.9 kg/m2 and to ≥ 40 kg/
m2 groups, respectively (all p<0.001). Percent weight loss was similar in each BMI category: 3.7%, 4.0%, 4.0% and 3.9%,
respectively (p<0.001).
Conclusions: This service evaluation demonstrates that 12 week referral to a commercial organisation is as effective for
people with high BMIs as for those who are moderately overweight.
Keywords: Obesity, Treatment, Weight management, Body mass index, Weight outcomesBackground
In a previous paper we have examined the rate and extent
of weight loss in a primary care/commercial weight
management organisation (CWMO) partnership scheme
(called Slimming on Referral). In that paper 34,271 patients
were referred by their health care professionals to a UK
commercial weight management organisation, Slimming
World, for 12 weekly sessions [1]. Data were reported for
the whole population, for completers (those who attended
10 of 12 sessions) versus non-completers, and for men and
women [1]. There is now a growing body of data* Correspondence: james.stubbs@slimming-world.com
1Nutrition and Research Department, Slimming World, Clover Nook Road,
Somercotes, Alfreton, Derbyshire DE55 4RF, UK
2University of Derby, Kedleston road, Derby, Derbyshire DE22 1GB, UK
Full list of author information is available at the end of the article
© 2013 Stubbs et al.; licensee BioMed Central
Commons Attribution License (http://creativec
reproduction in any medium, provided the orsuggesting that commercial diet and lifestyle programmes
are effective in the general population [1-8]. However, it is
not clear from current published studies whether lifestyle
interventions are as effective in patients with higher BMIs
than for those who are moderately overweight [1,2].
The purpose of the current analysis was to examine
the effectiveness of a primary care/CWMO partnership
scheme in patients of different BMI categories. Data were
collected from participants in the slimming on referral
scheme between May 2004 and November 2009, who had
time to finish their full 12-week referral. This resulted in
the inclusion of 38,614 patients who were referred from
within 77 Primary care Trusts or NHS Trusts, for whom
data on weight, height, age and gender were collected. Of
these there were 2,625 cases where the data for one orLtd. This is an Open Access article distributed under the terms of the Creative
ommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and
iginal work is properly cited.
Table 1 Patient characteristics at week 1 of the referral scheme and weight change by start BMI category
BMI < 30 kg/m2 BMI 30–34.9 kg/m2 BMI 35–39.9 kg/m2 BMI ≥ 40 kg/m2
Total n=3697 Total n=11759 Total n=9902 Total n=8913
Mean SD Mean SD Mean SD Mean SD f-value p-value
Height (m) 1.65 0.08 1.64 0.08 1.64 0.08 1.64 0.08 48.60 <0.001
Weight (kg) 76.8 8.0 88.0 9.6 100.8 10.9 122.3 18.6 19885.38 <0.001
Age (years) 48.1 15.0 48.1 14.8 47.2 14.6 45.8 13.4 64.43 <0.001
Weight change (kg) −2.9 2.8 −3.6 3.2 −4.1 3.7 −4.8 4.4 346.58 <0.001
Percent weight change −3.7 3.6 −4.0 3.6 −4.0 3.6 −3.9 3.5 7.06 <0.001
Weeks attended 8.7 3.6 8.9 3.5 8.8 3.6 8.9 3.5 0.19 0.905
Start BMI (kg/m2) 28.2 1.4 32.5 1.4 37.3 1.4 45.4 5.2 44536.13 <0.001
End BMI (kg/m2) 27.2 1.7 31.2 1.8 35.8 1.9 43.6 5.3 37989.02 <0.001
BMI change (kg/m2) −1.1 1.0 −1.3 1.2 −1.5 1.3 −1.8 1.6 387.75 <0.001
Proportion achieving 5% Weight loss 33.4% 36.6% 36.4% 35.8% 4.10 0.006
Proportion achieving 10% Weight loss 5.5% 6.1% 6.2% 5.4% 3.69 0.011
Stubbs et al. BMC Research Notes 2013, 6:161 Page 2 of 4
http://www.biomedcentral.com/1756-0500/6/161more of the 12 referral vouchers issued per participant was
unclear or could not be resolved (spoiled vouchers, illegible
writing etc.) and 1,718 cases where the participant com-
pleted the scheme outside of the 14 (12 plus 2) week time
window, due to circumstances such as bereavement or ill-
ness. This left 34,271 in the present study. 80 participants
were included in the database but there was no data for
their date of birth. Age data are reported excluding these
subjects. Some participants went on to self-fund further at-
tendance following the initial 12-week referral and others
were offered subsequent 12-week referral packages from
their health care team. Results for the latter are reported
elsewhere [9]. The data in this analysis covers the initial
12-week sessions of the referral scheme.
Data for this service evaluation was collected as part of
routine data collection within the referral programme. At
the point of referral patients’ gender, date of birth and
height were recorded by the health professional. When the
patient enrolled at the weight management group (week 1
of the referral), their start weight and date were recorded.
Each week the patient returned to group their weight
change was recorded along with date of attendance. The
same calibrated scales were used each week at a given
group to record weight and weight change. The collected
data were sent to the research team for input into the refer-
ral database.
This work is categorised as a service evaluation under the
Ad Hoc Advisory Group on the Operation of NHS Re-
search Ethics Committees, guidelines (2006). Existing data
were anonymised and analysed as an intervention in use
only to ask the question "What standard does this ser-
vice achieve?"
Data were extracted from the referral database, and
subjected to a number of parameter checks for outliers,
and anomalous data entry. Anomalies were checked againstthe raw source data to resolve any issues that arose. From
the raw data collected, start BMI, end BMI, BMI change,
weight change and percent weight change were calculated.
There was considerable variability in the number of ses-
sions attended, ranging from 1–12 weeks. Mean attendance
was 8.9 of 12 sessions.
The end weight was calculated based on the members’
last attendance at group during the referral period using
the Last Observation Carried Forward approach [10].
For the current analysis weight loss outcomes were
analysed by the BMI categories <30 kg/m2, 30–34.9 kg/m2,
35–39.9 kg/m2 and ≥40 kg/m2. The effects of different fac-
tors on weight loss between BMI categories were assessed,
by fitting linear models and examining the significance of
fitted terms in these models, through regression and ana-
lysis of variance. All analysis was performed using the
GENSTAT 5 statistical program (Genstat 5 Rothampstead
Experimental Station, Harpenden, UK). Results are ex-
pressed as mean (SD).
Findings
The physical characteristics and weight outcomes by BMI
category are given in Table 1. Eleven percent had a start
BMI <30 kg/m2, 34% between 30–34.9 kg/m2, 29% be-
tween 35–39.9 kg/m2 and 26% had a start BMI ≥40 kg/m2.
Weight, end BMI, BMI change and absolute weight loss all
increased with increasing BMI category (all p<0.001). Ab-
solute weight losses over the 12 week study period were
2.9, 3.6, 4.1, and 4.8 kg for the BMI categories <30 kg/m2,
30–34.9 kg/m2, 35–39.9 kg/m2 and ≥40 kg/m2, respect-
ively. Regression analysis showed that after adjusting for
age and gender, relative to the <30 kg/m2 group, absolute
weight losses were 0.8, 1.4 and 2.4 kg more for the 30–34.9
kg/m2, 35–39.9 kg/m2 and ≥40 kg/m2, groups, respectively
(all p<0.001). Percent weight loss was similar in each BMI
Stubbs et al. BMC Research Notes 2013, 6:161 Page 3 of 4
http://www.biomedcentral.com/1756-0500/6/161category at 3.7, 4.0, 4.0 and 3.9% for BMI categories <30
kg/m2, 30–34.9 kg/m2, 35–39.9 kg/m2 and ≥40 kg/m2.
Regression analysis showed that after adjusting for age and
gender, relative to the <30 kg/m2 group, percent weight
losses were 0.3, 0.3 and 0.2% greater for the 30–34.9 kg/
m2, 35–39.9 kg/m2 and ≥40 kg/m2 groups, respectively
(all p<0.001). For each BMI category those achieving 5%
weight loss were 33, 37, 36 and 36%, respectively (main
effect, p=0.006). Regression analysis showed that significant
differences occurred between the BMI categories <30 kg/
m2 and 30–34.9 kg/m2 (p=0.028). The percentage of those
losing 10% in their first 12 sessions by BMI category were
6, 6, 6 and 5% respectively (main effect, p=0.011). Specific
group differences were not significant in regression com-
parisons. There was no significant difference in the number
of weeks attended as a function of BMI category (p=0.905).
The current analysis illustrates that percent weight loss
was consistent across the BMI range and that those with
BMIs ≥40 (who represented 26% of participants referred
from primary care) lost a similar percentage of their initial
body weight as other participants at a lower BMI. In the
present service evaluation, participants followed a group
support programme and dietary plan, which is structured
around ad libitum intake of low energy dense foods, prin-
ciples of energy balance and appetite regulation to reduce
energy intake, with additional guidance to ensure a ba-
lanced diet [11]. The present data set suggests that partici-
pants with a BMI ≥40 can achieve higher absolute and
similar percent weight losses to their counterparts at lower
BMIs when following a low energy density dietary plan,
ad libitum.
Average start BMI of the study population was in the
range that would be recommended for more intensive in-
terventions such as pharmacotherapy and for a significant
percentage, bariatric surgery [12,13]. Start BMI averaged
36.8 kg/m2 and 26% of this referral population had a
BMI ≥40 kg/m2. This suggests that lifestyle interventions
can work in populations with BMIs that are normally
recommended to receive secondary or tertiary care.
As this was a service evaluation, it was limited by the
absence of a control group and the fact that the results
were based upon those people who joined a group, ra-
ther than intention to treat. The study only observed
weight changes over 12 weekly sessions and there was
no longer-term follow up. Key strengths were that the
referral programme evaluation assessed the effectiveness
of the programme as it runs in real life, the sample size
was large and conducted in members of the general pub-
lic aiming to control their weight in their everyday lives.Conclusion
Referral to a commercial organisation is as effective for
people with high BMIs as for those who are lessoverweight and attendances were similar between BMI
categories.
Abbreviations
CWMO: Commercial weight management organisation; SD: Standard
Deviation; BMI: Body Mass Index; NHS: National Health Service.
Competing interests
RJS, DJB, JB, CP, AA and JL work for Slimming World. SW was supported by
Slimming World for the analysis and preparation of this manuscript.
Authors’ contributions
JS, DB, JB, CP and SW collated the data, JS, CP, AA and JL were involved in
the design of the study, JS and SW were involved in the statistical analysis,
JS, CP and DB drafted the manuscript. All authors read and approved the
final manuscript.
Acknowledgement
We are grateful to GW Horgan of Biomathematics and Statistics Scotland, for
conducting an independent statistical analysis of the data. We would like to
thank the Slimming World on Referral team for entry of the raw data and
their general support to all primary care/commercial partnerships.
Funding
The analysis of the data was funded by Slimming World.
Author details
1Nutrition and Research Department, Slimming World, Clover Nook Road,
Somercotes, Alfreton, Derbyshire DE55 4RF, UK. 2University of Derby,
Kedleston road, Derby, Derbyshire DE22 1GB, UK. 3Public Health Nutrition
Research Group, University of Aberdeen, Aberdeen AB25 2ZD, UK.
Received: 16 October 2012 Accepted: 22 April 2013
Published: 24 April 2013
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doi:10.1186/1756-0500-6-161
Cite this article as: Stubbs et al.: Service evaluation of weight outcomes
as a function of initial BMI in 34,271 adults referred to a primary care/
commercial weight management partnership scheme. BMC Research
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Service evaluation of weight outcomes as a function of initial BMI in 34,271 adults referred to a primary care/commercial weight management partnership scheme

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