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Patient Preference and Adherence 2016:10 1547–1559
Patient Preference and Adherence Dovepress
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ORIGINAL RESEARCH
open access to scientific and medical research
Open Access Full Text Article
http://dx.doi.org/10.2147/PPA.S103649
Weight loss intervention adherence and factors
promoting adherence: a meta-analysis
Mark Lemstra
1
Yelena Bird
2
Chijioke Nwankwo
2
Marla Rogers
3
John Moraros
2
1
Alliance Wellness and Rehabilitation,
Moose Jaw,
2
School of Public Health,
3
College of Medicine, University of
Saskatchewan, Saskatoon, SK, Canada
Background: Adhering to weight loss interventions is difficult for many people. The majority
of those who are overweight or obese and attempt to lose weight are simply not successful.
The objectives of this study were 1) to quantify overall adherence rates for various weight loss
interventions and 2) to provide pooled estimates for factors associated with improved adherence
to weight loss interventions.
Methods: We performed a systematic literature review and meta-analysis of all studies published
between January 2004 and August 2015 that reviewed weight loss intervention adherence.
Results: After applying inclusion and exclusion criteria and checking the methodological quality,
27 studies were included in the meta-analysis. The overall adherence rate was 60.5% (95% confi-
dence interval [CI] 53.6–67.2). The following three main variables were found to impact adherence:
1) supervised attendance programs had higher adherence rates than those with no supervision (rate
ratio [RR] 1.65; 95% CI 1.54–1.77); 2) interventions that offered social support had higher adher-
ence than those without social support (RR 1.29; 95% CI 1.24–1.34); and 3) dietary intervention
alone had higher adherence than exercise programs alone (RR 1.27; 95% CI 1.19–1.35).
Conclusion: A substantial proportion of people do not adhere to weight loss interventions.
Programs supervising attendance, offering social support, and focusing on dietary modification
have better adherence than interventions not supervising attendance, not offering social support,
and focusing exclusively on exercise.
Keywords: community based, obesity, social support, program adherence
Introduction
Obesity is a common chronic condition that increases the risk of numerous health
problems, including cardiovascular diseases, diabetes, cancer, and mental health issues.
1
Substantial weight loss is not required to start to see health benefits. For example, a 5%
reduction in body weight is enough to improve health outcomes.
1
According to data
from the 1998 National Health Interview Survey, 50% of obese men and 58% of obese
women in the US are actively trying to lose weight.
2
Regrettably, despite the efforts of
a large portion of the population, the prevalence of obesity has remained high.
3
It is especially difficult to lose weight among those suffering from obesity, as it is
a complex condition created by diverse genetic, environmental, cultural, and socioeco-
nomic pathways. For example, a recent study concluded that the chances of returning
to a normal weight for someone who is already obese are extremely low: one in 210
chances for men and one in 124 chances for women.
4
According to the National Health
Interview Study mentioned earlier, the most commonly reported weight loss methods
are as follows: 1) calorie restriction alone, 2) eating less fat, and 3) exercising more.
2
All of that said, moderate weight loss for health reasons is possible, even among
those who are obese. For example, a study of 4,034 obese adults in the US found that
Correspondence: Mark Lemstra
Alliance Wellness & Rehabilitation
B70 500 – 1st Ave NW Moose Jaw,
SK S6H 3M5 Canada
Email marklemstra@shaw.ca
Journal name: Patient Preference and Adherence
Article Designation: Original Research
Year: 2016
Volume: 10
Running head verso: Lemstra et al
Running head recto: Weight loss intervention adherence
DOI: http://dx.doi.org/10.2147/PPA.S103649
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40% lost .5% of their body weight in the past year and 20%
lost .10%.
5
However, participants need to adhere to evi-
dence-based weight loss methods to lose weight and maintain
weight loss in the long term. A meta-analysis of 18 random-
ized controlled trials (RCTs) found that diet and exercise pro-
grams combined were clearly superior to diet programs alone
or exercise programs alone.
6
A meta-analysis of 29 studies
looking at long-term (5 years) weight loss maintenance among
those who participated in structured weight loss programs,
found that the average individual maintained at least 3 kg of
weight loss and at least a 3% reduction of initial body weight.
The authors found that those who lost more weight prior to
starting the programs were more likely to keep weight off and
those who exercised more were able to better maintain their
weight loss than those who did not.
7
Adhering to healthy weight loss behaviors is required for
weight loss initially and in the long term. If participants are
unable to adhere to weight loss strategies, they will not lose
weight. Problems with attrition and nonadherence exist for
intervention programs that are often evaluated in the short
term. For example, a meta-analysis of 80 studies on weight
loss interventions with a control group found a mean attrition
rate of 31%.
8
In a meta-analysis of 45 RCTs of nonsurgical
weight loss interventions in obese adults, it was found that
28.4% of participants dropped out of the study prior to the
maintenance phase and that many of these dropouts were
due to not meeting adherence criteria or weight loss criteria
during the study phase.
9
An important part of advancing weight loss interventions
is to understand how to improve adherence to weight loss
behaviors. In any health behavior, nonadherence is a problem.
The World Health Organization has identified nonadherence
as a problem, “of striking magnitude”.
10
Behavior change
is complex, and even in life-threatening situations, it is dif-
ficult for people to adhere to medical advice. For example,
a report from Statistics Canada found that among smokers
with new diagnoses of chronic diseases: 75% of patients with
a recent diagnosis of heart disease, 78% of those with a new
cancer diagnosis, 74% of those with stroke, and 96% of those
with respiratory disease did not quit smoking.
11
Concerning
weight-related health risks, more optimistic results have
been reported about behavioral changes. For example, a
study of 600 participants with a new diagnosis of type II
diabetes found that only 20 people were able to change all
their cardiovascular disease risk behaviors within 1 year, but
many were able to decrease their Body Mass Index (BMI)
and decrease their total daily calorie intake.
12
In regard to weight loss interventions among those with
obesity, there have been no meta-analyses investigating
factors that improve adherence rates. The objective of this
review and meta-analysis was to quantify adherence rates for
various weight loss intervention types and to provide pooled
estimates for factors associated with improved adherence to
weight loss interventions.
Methods
A systematic literature review was performed, accessing the
following databases: Medline, PubMed, ProQuest, CINAHL,
Cochrane Central, Global Health, ISI Web of Knowledge,
ProQuest, SCOPUS, and EMBASE. Search dates ranged
from January 2004 to August 2015.
Subject search descriptors included terms listed in
Figure 1. Search terms included relevant weight loss or
reduction interventions and adherence or behavior modifi-
cation (Supplementary material). Adherence was defined as
completion of the weight loss program or, in certain cases,
was assessed by the level of consistency with the weight loss
intervention of interest. Reference sections of each article
were reviewed for additional articles. Unpublished articles
were not included in our search.
The following inclusion criteria were used in the
search:
1. Article should clearly describe adherence to a weight
loss program, and the said program should be neither
pharmacological nor surgical.
2. Article should have quantifiable data describing the effect
size (ie, some absolute or relative measure of program
adherence).
3. Article should describe a study that is prospective in
nature (ie, an RCT, a quasiexperimental, or a cohort
study).
4. Article should be publicly available.
5. Article should be published in the English language.
The search strategies excluded opinion articles, letters to
the editor, case reports, and case studies.
Titles were initially reviewed for relevance and to remove
duplication. The articles that remained were then subjected to
full abstract review in order to apply inclusion and exclusion
criteria. Finally, the remaining articles were subjected to full
review and methodological quality evaluation by a panel of
two reviewers (CN and ML). Unanimous agreement was
sought; however, when there was disagreement, a tie breaker
was used with a third author (JM).
We used methodological quality checklists for experi-
mental and quasiexperimental designs from Greenhalgh
et al.
13
These checklists are a validated modification of
the Cochrane Effective Practice and Organization of Care
checklist and contain ten questions covering six areas of
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Weight loss intervention adherence
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Figure 1 Flow diagram for included studies.
methodological rigor (eleven questions for quasiexperimental
designs). The lists made provisions for assessing bias with
the different study designs. A score of six was required in
order to be accepted for review (ie, a score .50%).
14,15
The
checklists are presented in Tables 1 and 2.
A computer program that utilized a random effects model,
taken from Fleiss,
16
was built to take interstudy heterogeneity
into account. The statistical basis and its assumptions have
been previously described in detail elsewhere.
17–19
At least
four articles were required for statistical pooling.
Results
Systematic review
The initial search generated 1,563 articles of which 260
articles were duplicates and removed, leaving 1,303 articles
to screen abstracts. After the initial screening, 89 articles
were included in the full review with 56 articles removed
based on the inclusion/exclusion criteria. The remaining 33
articles were then subjected to full methodological review
by two reviewers. There was disagreement on only one
article that was included based on tie-breaking vote from
a third reviewer. In total, six of the articles did not meet
methodological requirements, leaving 27 articles for meta-
analysis. Figure 1 depicts the search process. Studies included
in the analysis and their detailed results are presented in
Table 3.
20–46
Operationalizing adherence
Intervention adherence ranged significantly from 10%
20
to 99.5%.
29
Adherence was operationalized in 13 studies,
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Lemstra et al
Table 1 Methodology checklist for experimental designs
Authors:
Study title:
Yes No
A. Research question and design
1. Was there a clear research question and was this important and sensible?
2. If the study was nonrandomized, could a randomized controlled design have been used?
B. Baseline comparability of groups
3. [RCTs only]: Was allocation adequately concealed by a rigorous method (eg, random number)?
4. Were appropriate measures of baseline characteristics taken in all groups before the intervention and
were study groups shown to be comparable in all characteristics likely to inuence outcome?
C. Outcome measures
5. Was the primary outcome measure valid (ie, do two independent raters agree that this was a sensible
and reasonable measure of performance or outcome)?
6. Was the primary outcome measure reliable (ie, do two independent raters agree on the nature and
extent of change)?
D. Protection against contamination
7. Is it unlikely that the control unit of allocation (professional, practice, institution, and community)
received the intervention through contamination?
E. Protection against bias
8. Were outcomes measured by “blinded” observers or were they objectively veried (eg, quantitative
measures recorded prospectively and independently)?
F. Follow-up
9. Was there complete follow-up of participants (ideally .80%)
10. Was follow-up continued for long enough for the primary outcome measure to show an impact and
for sustainability to be demonstrated?
Note: Passing score for experimental designs =6/10.
Abbreviation: RCT, randomized controlled trial.
Table 2 Quasiexperimental designs
Authors:
Study title:
Yes No
A. Research question and design
1. Was there a clear research question, and was this important and sensible?
2. If the study was nonrandomized, could a randomized controlled design have been used?
B. Protection against secular changes
3. Was the intervention independent of other changes over time?
4. Were there sufcient data points to enable reliable statistical inference?
5. Was a formal statistical test for trend correctly undertaken?
C. Outcome measures
6. Was the primary outcome measure valid (ie, do two independent raters agree that this was
a sensible and reasonable measure of performance or outcome)?
7. Was the primary outcome measure reliable (ie, do two independent raters agree on the
nature and extent of change)?
D. Protection against detection bias
8. Was the intervention unlikely to affect data collection (eg, sources and methods of data
collection were the same before and after the intervention)?
9. Were outcomes measured by “blinded” observers or were they objectively veried (eg,
quantitative measures recorded prospectively and independently)?
F. Completeness of data set and follow-up
10. Does the data set cover all or most of the episodes of care (or other unit of analysis)
covered by the study (ideally .80%)?
11. Was follow-up continued for long enough for the primary outcome measure to show an
impact and for sustainability to be demonstrated?
Note: Passing score for quasiexperimental designs =6/11.
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Weight loss intervention adherence
Table 3 Included studies in meta-analysis
Primary authors;
year, country
study conducted
Study
design
Study
duration
Number
of study
participants
Type of weight
loss intervention
Adherence rate Quality
scores
Baseline
BMI
Predictors of
adherence
Other moderators (work
place intervention, social
support, nancial incentive,
or mandatory intervention)
Acharya et al;
20
2009,
USA
RCT 12 months 127 Group sessions,
energy/calorie goal,
and diet
Energy/calorie goal – 10%
Attendance – 44%
Self-monitor – 22%
6/10 pass – – –
Annunziato et al;
21
2009, USA
RCT 12 months 42 Diet – MR Attendance – 70%
MR – 41.5%
8/10 pass 31.9 – –
Ard et al;
22
2008,
USA
Pre/post 5 months 377 Calorie reduction,
diet, and PA
Attendance – 45.6%
PA goal – 36.9%
8/11 pass 35.1 – –
Austin et al;
23
2013,
USA
Pre/post 4 months 82 LEARN Attendance – 48.8%
Calorie goals – 64.5%
Step goals – 80.9%
6/11 pass 33.0 Higher adherence: older
age, increasing income,
and increasing education
Lower adherence: more
children living at home,
young age, and low
socioeconomic status
Financial incentive
Barteld et al;
24
2011,
USA
RCT 18 months 507 Group session,
DASH diet, and
exercise
Food record – 15.7%
Exercise – 14%
Attendance – 53.8%
7/10 pass 33.7 – –
Befort et al;
25
2008,
USA
RCT 4 months 34 Diet, PA,
motivational
interview, and health
education
Attendance – 52% 6/10 pass 39.8 – –
Burke et al;
26
2009,
USA
RCT 24 months 210 Paper record, PDA,
and PDA with
feedback
Attendance/retention: cohort
1 (n=73) – 90% (24 months)
Cohort 2 (n=63) – 76%
(18 months)
Cohort 3 (n=74) – 92%
(6 months)
6/10 pass 33.4 – –
Carson et al;
27
2013,
USA
RCT 6 months 92 Self-monitoring,
goal setting,
stimulus control,
nutrition education,
and cognitive
restructuring
Attendance – 64.5%
Monitoring – 62.1%
6/10 pass 38.1 Higher adherence:
having a social contact
Social support
Carter et al;
28
2013,
UK
RCT 6 months 128 MMM smartphone
app
Attendance – 61.7%
MMM app – 16% (N=43)
7/10 pass 34.0 Lower adherence:
higher BMI and poorer
health status
–
(Continued)
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