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

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choosing vertical sleeve gastrectomy, and more work problems compared to those

undergoing gastric bypass. Weight loss after bariatric surgery was predicted by pre-

operative 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

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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 obesity-

related 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

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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 (~20-

30%) 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).

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The aims of our study were to determine whether there are any differences in the pre-

operative, 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 cut-

off 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

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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).

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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

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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 post-

surgery and determine the association of those factors with weight-loss at 1 year post-

surgery. 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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