Title: Psychological characteristics, eating behaviour and quality of life assessment of
obese patients undergoing weight loss interventions
Authors: Alexander D. Miras 1*, Werd Al-Najim 2*, Sabrina N. Jackson 2,3, Jenny McGirr2,
Lisa Cotter 2, George Tharakan 1, Amoolya Vusirikala 2, Carel W. le Roux 2, 3, Christina G.
Prechtl 2 and Samantha Scholtz 2
Affiliations
1 Section
of Investigative Medicine, Division of Diabetes, Endocrinology & Metabolism,
Imperial College London, 6th floor Commonwealth Building, Hammersmith Hospital, Du
Cane Road, London, W12 0NN, UK
2
Metabolic Medicine Research Unit, Charing Cross Hospital, Fulham Palace Road,
London W6 8RF
3 Diabetes
Complications Research Centre, UCD Conway Institute, School of Medicine
and Medical Science, University College Dublin, Dublin 4, Ireland
* These
authors contributed equally to the manuscript
Short title: Psychological characteristics and bariatric surgery outcomes
Declaration of Conflicting Interests
There are no conflicts of interest for any of the authors.
Funding source: MRC Clinical Training Fellowship G0902002
1
Author for correspondence
Dr Alexander D. Miras
Section of Investigative Medicine
Division of Diabetes, Endocrinology & Metabolism
Imperial College London
6th floor Commonwealth Building
Hammersmith Hospital
Du Cane Road
London
W12 0NN
UK
Telephone number: +44 7958377674
Email: a.miras@nhs.net
2
Abstract
Background and Aims: Bariatric surgery is the most effective treatment for obesity.
However, not all patients have similar weight loss following surgery and many
researchers have attributed this to different pre-operative psychological, eating
behaviour, or quality of life factors. The aim of this study was to determine whether
there are any differences in these factors between patients electing to have bariatric
surgery compared to less invasive non-surgical weight loss treatments, between
patients choosing a particular bariatric surgery procedure, and to identify whether
these factors predict weight loss after bariatric surgery.
Material and Methods: This was a prospective study of 90 patients undergoing either
gastric bypass, vertical sleeve gastrectomy, or adjustable gastric banding and 36
patients undergoing pharmacotherapy or lifestyle interventions. All patients
completed seven multi-factorial psychological, eating behaviour and quality of life
questionnaires prior to choosing their weight loss treatment. Questionnaire scores,
baseline body mass index, and percent weight loss at one year after surgical
interventions were recorded.
Results and Conclusions: Surgical patients were younger and had a higher BMI than
non-surgical patients. Patients opting for adjustable gastric banding surgery were
more anxious, depressed and had more problems with energy levels than those
3
choosing vertical sleeve gastrectomy, and more work problems compared to those
undergoing gastric bypass. Weight loss after bariatric surgery was predicted by preoperative scores of dietary restraint, disinhibition, and pre-surgery energy levels.
These results generate a number of hypotheses that can be explored in future studies
and accelerate the development of personalised weight loss treatments.
Key words: bariatric surgery, gastric bypass, vertical sleeve gastrectomy, gastric
banding, psychological factors, eating behaviour, quality of life, predictors of weight
loss
4
Introduction
Over the past two decades the obese population has increased from 13% of men and
16% of women in 1993 to 24% of men and 26% of women by 2011 (1). Psychological
disorders such as depression and anxiety are very often prevalent amongst the obese
population (2) and such disorders can potentially complicate the treatment of obesity
(3).
Bariatric surgery has become an increasingly popular treatment option for individuals
with obesity, as sustained post-operative weight loss and improvements in obesityrelated comorbidities make it the most effective treatment for this population (4). The
prevalence of psychological disorders is high in obese individuals opting for bariatric
surgery (5) and in most centres patients undergo psychological evaluation before a
decision is made as to whether or not they are suitable for surgery (2). However,
although most researchers agree that psychosocial and behavioural factors such as
depression, anxiety and binge eating can contribute to poor postoperative outcomes,
studies are conflicting regarding their prevalence (6) and how they may affect bariatric
surgery outcomes.
It is generally assumed that psychological morbidity may make it more difficult to
maintain good eating habits and therefore sustained weight loss (7). Although bariatric
5
surgery has many health benefits and is considered very effective treatment for the
management of severe obesity, there are still a significant proportion of patients (~2030%) that fail to lose a significant amount of weight (3). This is thought to be due to a
number of different factors including type of surgery, eating habits and psychological
morbidity.
To date, it has been a challenge to determine which psychological factors might
influence bariatric surgery outcomes. Many studies looking at possible predictors for
weight loss outcomes after bariatric surgery already exclude those with severe
psychopathology; therefore no clear psychological predictors have emerged (8). In
addition, methodological weakness, different definitions of successful outcome, failure
to differentiate between types of bariatric surgery, small patient groups and different
follow up periods have complicated the interpretation of data (9). The assumption
that those patients opting for surgery suffer from greater psychological comorbidity
leading to their choice of more invasive treatment has little supporting evidence and it
is also not known whether there are differences in baseline psychological health
between patients who choose different operations, e.g. Adjustable gastric banding
(BAND) vs. Roux-en-Y gastric bypass (RYGB).
6
The aims of our study were to determine whether there are any differences in the preoperative, psychological, quality of life and eating behaviour characteristics between i)
patients electing to have bariatric surgery compared to less invasive non-surgical
weight loss treatments, ii) patients choosing a particular bariatric surgery procedure,
and iii) identify whether these characteristics predict weight loss after bariatric
surgery. By identifying specific factors that predict weight loss we wish to add to the
growing body of literature aimed at improving patient choice and personalisation of
obesity treatment programmes.
Materials and methods
Design
In this prospective study data were collected prospectively and analysed
retrospectively. The study was conducted by the Charing Cross NHS hospital obesity
clinic and Imperial College London. On the day of their first appointment at the obesity
clinics, 126 consecutive patients were asked to complete a set of questionnaires
regarding their psychological characteristics, eating behaviour and quality of life.
Fifteen patients were excluded as they did not understand the questionnaire
instructions. The study took place in 2010-2011 and was approved by the Clinical
Governance and Patient Safety Committee at Imperial College London, ref: 09/808.
7
Three types of treatments are available in our clinics: lifestyle, pharmacotherapy and
bariatric surgery. Management decisions are taken collectively by the patient and
clinician and are independent of patient responses in the pre-assessment
questionnaires. Patients are excluded from surgical treatments only if they are at
unacceptably high risk for a general anaesthetic or if the have active and severe mental
health disease. Basic clinical characteristics including BMI were recorded during the
first visit and 1 year after surgical intervention.
Assessments
Questionnaires used to assess psychological characteristics, eating behaviour and
quality of life were:
Psychological characteristics

Barratt Impulsivity Scale-11 (BIS-11) is a self-report measure of impulsivity (a personality
trait) (10). A higher score represent higher impulsivity rate.

The Hospital Anxiety and Depression Scale (HADS) assess depression and anxiety. The cutoff values for anxiety and depression levels are: 0-7 ‘normal’, 8-10 ‘borderline abnormal’,
and 11-21 ‘abnormal’ (11).
8

Behavioural Activation Scale (BAS) measures appetitive motives, i.e. to move
toward something desired. It consists of three sub-scales: Reward Responsivity (RR)
measures positive responses to the anticipation of reward; Drive (DR) measures the
persistent pursuit of desired goals; and Fun-Seeking (FS) measures a willingness to
approach a new event on the spur of the moment. In contrast, the Behavioural
Inhibition Scale (BIS) measures aversive motivation, i.e. to move away from
something unpleasant, such as punishment or negative events (12). Higher scores
in both scales mean higher tendency towards the measured factor.
Eating behaviour

The Three Factor Eating Questionnaire (TFEQ) is a self-report psychometric instrument that
assesses eating behaviour from three dimensions: cognitive restraint (consciously trying to
resist eating in order to control body weight; disinhibition (loss of control over eating) and
the susceptibility to hunger (13). Maximum scores for the sub-scales are: 21, 16, and 14,
respectively with higher scores indicating greater cognitive restraint, uncontrolled eating,
and food intake, in response to feelings of hunger.

The Eating Disorders Examination Questionnaire (EDE-Q) is a self-report instrument
used to assess eating behaviours over a period of 28 days. The EDE-Q is adapted
9
from the original Investigator Based Interview but retains the format of including 4
subscales: Restraint, shape, weight, and eating concern, and a global score (14). The
scores range from 0-6 with the global scale measuring the severity of the eating
disorder psychopathology.
Quality of life

The Short Form 36 (SF-36) health survey is a self-administered questionnaire
containing 36 items. It measures functional status, well-being, and the overall
evaluation of health. Scores range from 0-100, higher scores indicate better health
status (15).

Impact of Weight on Quality of Life (IWQOL) assesses the impact of an individual’s
weight on their physical function, self-esteem, sexual life, public distress and work
problems, and the total quality of life of all aspects combined together to give an
overall evaluation. Higher scores indicate poorer quality of life as a result of an
individuals’ weight (16).
Statistical methods
Descriptive data are shown as mean ± SD. Groups were compared either with unpaired
t-tests/Mann Whitney U or one way ANOVA/one way ANOVA on ranks depending on
10
normality distribution. Pair-wise post ANOVA comparisons were performed using the
Tukey multiple comparison correction testing. Psychological predictors of percentage
weight loss were determined using linear regression. The statistical software used was
Graph Pad Prism 5 and statistical significance was accepted at the p<0.05 level.
Results
Out of the 126 patients, 90 chose and actually underwent bariatric surgery and 36
chose to undergo either lifestyle or pharmacotherapy treatments. Out of the 90
surgical patients 72 underwent Roux-en-Y gastric bypass surgery (RYGB), 12 adjustable
gastric banding surgery (BAND) and 6 vertical sleeve gastrectomy (VSG). The basic
clinical characteristics of both surgical and non-surgical groups, as well as of the
patients in each surgical sub-group are shown in Table 1.
Comparisons between surgical and non-surgical patients
The surgical patients were significantly younger and heavier than the non-surgical
group (table 1). There were significant differences in reward responsiveness and
behavioural inhibition scores in the BIS/BAS questionnaire, with the surgical group
scoring significantly higher than the non-surgical group (Table 2). There were no
11
significant differences between the surgical and non-surgical groups in terms of eating
behaviour (Table 3) or quality of life parameters (Table 4).
Comparisons between surgical subgroups
Anxiety and depression were significantly higher in the BAND group compared to the
VSG group, but not compared to RYGB (Table 2). There were no differences between
the three sub-groups in any of the eating behaviour factors as measured by TFEQ and
EDE-Q (Table 3). In quality of life parameters measured by the SF-36, problems with
energy levels were significantly higher in the BAND group compared to the VSG group
but not compared to RYGB. However, impact of weight on work as measured by
IWQOL was significantly higher in the BAND compared to RYGB but not compared to
VSG (Table 4).
Pre-operative predictors of weight loss following bariatric surgery
SF-36 energy and TFEQ-cognitive restraint were both negatively correlated with the
percentage weight lost at 1-year post surgery while TFEQ-disinhibition was positively
correlated (Tables 3 and 4). No significant correlation was found between the other
parameters and percentage weight loss (Table 2).
12
Discussion
In this study we found that patients who opted for bariatric surgery had a higher BMI,
were younger, and had higher behavioural inhibition and reward responsiveness
compared to patients who chose non-surgical treatment options for obesity. The two
groups did not differ significantly in most other psychological, eating behaviour, or
quality of life characteristics. Furthermore we found that amongst patients choosing
surgical options, those that opted for the BAND had significantly higher anxiety and
depression, and more problems with energy levels than those who opted for VSG, and
more work problems than those choosing RYGB. Cognitive restraint and disinhibition
as measured by the TFEQ, and low energy levels as measured by SF-36, emerged as the
only baseline predictors of percentage weight loss at one year in patients who
underwent bariatric surgery of any type.
Comparisons between surgical and non-surgical patients
Our comparison of surgical and non-surgical patients suggests that patients who have
a higher BMI, especially at a relatively young age may be more inclined to choose an
invasive treatment option. Surprisingly, despite their higher BMI, patients opting for
surgery did not have significantly higher impulsivity, anxiety and depression, or worse
eating behaviour and quality of life as measured by the BIS-11, HADS, TFEQ, EDE-Q,
13
IWQOL, and SF-36 respectively compared to patients opting for non-surgical
treatments.
Patients opting for surgery did have significantly higher scores in behavioural inhibition
and reward responsiveness. Individuals with high behavioural inhibition tend to have
higher levels of anxiety and are more cautious with regards to risk taking behaviour
(12, 17). In this context, in our sample group, the decision to undergo a surgical
treatment may represent an exchange of perceived higher short-term risk (e.g. risk of
anaesthetic complications) in favour of lower long-term risk (e.g. reduction in obesity
related morbidity and current health complications).
Alternatively, observed
differences in behavioural inhibition and reward responsiveness may be related to the
lower age or higher BMI in the surgical group. Both behavioural inhibition and
behavioural activation, of which reward responsiveness is included, decrease with
increasing age (17) due to changes in personality characteristics including being less
fearful, less anxious and less depressed with age (12). Reward responsivity has been
linked to food craving, overeating, and preference for sweet and fatty food which, in
turn leading to weight gain over the long term and increased BMI (18).
14
In summary therefore, whilst the psychological, eating behaviour, and quality of life of
obese patient seeking a surgical compared to a non-surgical treatment did not differ
significantly, bariatric surgery may appeal more to those who are younger or who have
a higher BMI and are therefore at higher long term risk of obesity-related comorbidity.
Comparisons between surgical sub-groups
Only two studies to date have compared pre-surgical psychological profiles of bariatric
patients undergoing RYGB compared to BAND. Walfish (19) found no difference in
baseline scores of depression, anxiety, anger, and ‘self-assessed reasons for weight
gain’ between female BAND and RYGB patients but found that BAND patients had
higher rates of ‘eating when anxious’ than RYGB. On the other hand, Hood et al. (20)
found that RYGB patients had higher baseline depression, binge eating symptoms,
somatic complaints, and antisocial features than BAND patients.
In our study, we found that BAND patients had higher levels of depression and anxiety
than the VSG but not RYGB group. Importantly this was not explained by differences in
their age and BMI, suggesting a role for other factors. At the time of the study, VSG
was a relatively new treatment option, compared to BAND and RYGB. It may be that
patients at that time viewed VSG as irreversible and potentially more risky than the
15
other surgeries, and particularly the BAND. Those with higher depression and anxiety,
and therefore more cautious and less risk taking, may therefore have perceived BAND
as a safer and more acceptable intervention.
The weight related quality of life among the surgical sub-groups did not differ
significantly in the SF-36, but in the IWQOL, BAND patient scored significantly higher
for work problems than the RYGB but not VSG, indicating greater difficulties in carrying
out work effectively or from progressing at work as a result of their weight. In his study
in 1999, Anderson (21) found that BAND patient were of a higher socioeconomic status
than the RYGB. This may explain our findings to some degree, since BAND surgery is
technically less demanding and requires less hospitalization than RYGB surgery (22),
and may therefore appeal more to those in employment, especially if their work is
suffering. In keeping with higher anxiety and depression, BAND patients also reported
more problems with energy levels than VSG (and a non-significant trend for more
problems compared to RYGB).
Pre-operative predictors of weight loss following bariatric surgery
A number of attempts have been made to investigate whether weight outcomes could
be predicted from participants’ psychological and behavioural characteristics prior to
16
bariatric surgery. Previous studies examined a limited number of variables at a time
such as cognitive function, or psychological characteristics (e.g. (23)). For the majority
of variables examined, studies have shown no correlations with weight loss or
inconsistent findings. We add to this work, by finding that dietary dishinhibiton
according to the TFEQ scores and worse energy scores on SF-36 positively predicted
weight loss following surgery, and that TFEQ dietary restraint scores negatively
predicted weight loss following surgery.
Disinhibition with regards to eating behaviour results erratic eating and unplanned
meals and is associated with binge eating, a higher BMI and obesity (24). Bariatric
surgery, and in particular RYGB, result in decreased disinhibition and improved eating
behaviour, which may contribute to weight loss (25). In contrast to our findings,
previous studies have not found disinhibition to be a predictor of weight loss outcomes
(26). Bariatric surgery may modify erratic eating behaviour by various mechanisms,
including reducing the hedonic value of food (25).
Therefore those with higher
disinhibition and therefore erratic and emotional eating behaviour pre-operatively
may experience a greater benefit from these modifications than those where obesity
has been influenced by other factors.
17
We also found a negative correlation between TFEQ-Cognitive restraint and
percentage weight-loss. Dietary restraint is defined as a conscious effort to resist
eating with the aim of controlling body weight (27). In their study Sarwer et al. (28)
have found that higher baseline dietary restraint results in more weight loss following
RYGB as a result of better adherence to the post-operative diet. However, based on
the restraint theory, Polivy (29) argued that high dietary restraint can lead to increased
periods of over eating resulting in higher consumption of calories following dieting.
Our results are consistent with this finding and suggest that high baseline dietary
restraint can negatively influence long-term weight loss results.
SF-36 poor energy levels in this study were associated with poorer weight loss
following surgery. In bariatric patients, Dixon et al. (6) found that energy was not
correlated to weight-loss following surgery. However, lower energy levels caused by
the health complications of obesity pre-bariatric surgery can be strong motivators for
weight loss (7). As bariatric surgery improves the quality of health of obese patients,
most are likely to engage more in physical exercise, but those with poorer energy
levels to start with may not see as much improvement and may struggle more to
engage in physical activity resulting in less weight loss and poorer weight maintenance
at one year follow up.
18
While providing important new findings, the present study has a number of limitations.
Perhaps most critically is the different number of participants in the sub-surgical
groups, as in our sample, more patients opted for RYGB than BAND or VSG. In order to
determine predictors for weight loss, we collapsed all the sub-surgical patients in one
group. Therefore, most of the findings may have been driven by the RYGB group
potentially reducing the generalisability of the conclusions that can be drawn.
However, investigating an equal number of subjects in each sub-surgical group would
have reduced the power of the study to detect predictors. Furthermore, RYGB is the
most performed bariatric surgery worldwide (30) and our findings are therefore
representative of most bariatric surgery centres.
Psychological, eating behaviour, and quality of life parameters tend to be altered
following bariatric surgeries. Therefore, it may have been valuable to collect data postsurgery and determine the association of those factors with weight-loss at 1 year postsurgery. In addition, no information was available on other important factors i.e.
education, socioeconomic status, medical comorbidities, and functional impairment all
of which may also contribute to patient choice of treatment and to their psychological
characteristics, eating behaviour, and quality of life.
19
Although choosing an adequate sample size is critical to the overall findings, this study
was based on audit data collected prospectively over a fixed time period, and
therefore no power calculation was carried out. However, our data was collected from
a large cohort and the 1 year follow up period and comprehensive array of tests add
strength to our findings.
In summary, this study has highlighted the heterogeneity of obese patients presenting
for treatment and attempted to explore the factors which may influence treatment
choice and success. Future studies should attempt to phenotype patients according to
psychological and eating behaviour characteristics and examine outcomes with the aim
of personalising obesity treatments.
Declaration of Conflicting Interests
There are no conflicts of interest for any of the authors.
Funding Acknowledgements
Alexander D. Miras has received funding from an MRC Clinical Training Fellowship
G0902002, MRC Centenary Award, and an NIHR Clinical Lectureship. Christina G.
20
Prechtl was funded by the British Research Council (BRC). Carel W. le Roux has
received funding from the Science Foundation Ireland and the Moulton Foundation
UK. Samantha Scholtz was funded by a Wellcome Trust Research Training Fellowship.
The views expressed are those of the authors and not necessarily those of the funders,
NHS, the NIHR or the Department of Health.
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