Behavioural and psychological characteristics of patients


Patients who choose bariatric surgery compared to conservative weight loss treatment, had more positive expectations of the treatment outcomes and stronger beliefs in their ability to achieve these outcomes, according to researchers from the Oslo Bariatric Surgery Study (OBSS) The paper, ‘A comparison of behavioral and psychological characteristics of patients opting for surgical and conservative treatment for morbid obesity’, published in the BMC Obesity, also stated that patients starting conservative treatment had stronger beliefs in readiness to change physical activity levels.

It is known that a patient’s psychological characteristics can impact the success from bariatric surgery. Previous studies ­looking at the psychological differences between surgical and non-surgical patients have focused on psychopathological factors, such as depression, anxiety, eating disorders or problematic eating behaviours. The most consistent finding is that surgical patients more frequently report high levels of depressive symptoms than non-surgical patients.

The aim of this study was to compare patients scheduled for bariatric surgery with patients receiving conservative treatment for morbid obesity on measures of behavioural and psychosocial characteristics considered predictors of their adoption of and adherence to long-term lifestyle recommendations. The study measured baseline behaviour and psychological characteristics, such as self-efficacy, motivation, goal attainment, mental health, and social support, in patients awaiting bariatric surgery and non-surgical weight loss treatment.


The study used data from the OBSS, a prospective study of two cohorts of patients that will be followed over a 10-year period. The OBSS focuses on identification of psychosocial predictors of behavioural change and weight loss maintenance. All participants are assessed with self-report questionnaires at five time points; pretreatment (baseline), one, three, five and ten-years post-treatment.

Two groups of patients were recruited: patients scheduled for bariatric surgery (surgical group) and patients starting a conservative weight reduction treatment (non-surgical group). The inclusion criteria for both groups were BMI≥40 or BMI≥35, with obesity related comorbidity, age ≥18 years, and the ability to understand and comply with the study procedures.

The patients in the surgery group had previous failed attempts of sustained weight loss using conservative measures. Only patients with current, previous established or suspected psychiatric disorder were evaluated by a psychologist or a psychiatrist. There was no routine preoperative psychological screening. The patients were recruited from the Center for Morbid Obesity and Bariatric Surgery at Oslo University Hospital, between February 2011 and September 2013, after they had participated in a preoperative mandatory course. The course consisted of 36 hours (ten meetings), which included topics like treatment options, diet, physical activity, emotions, motivation, and behaviour change.

Current unhealthy eating habits were assessed using four items specifically constructed for this study (frequency of snacking between meals, snacking on sweets between meals, drinking soda between meals, and night eating) with response options ranging from (1) never to (5) always. Physical activity during the previous week was assessed using the International Physical Activity Questionnaire (IPAQ)-Short Form [26]. The mean scores were calculated by weighting the type of activity by energy requirements and reported as metabolic equivalent values (MET). Alcohol consumption during the past 12 months was assessed by measuring the frequency of consuming one or more units of alcohol during the past year, with response options ranging from (1) never consumed alcohol to (9) daily or almost daily consumption. Intoxication was evaluated using response options ranging from (0) no alcohol use to (5) visibly intoxicated 10 times or more. Self-monitoring of weight was measured by one item with response options ranging from (1) almost never to (7) more than once a day.

Motivation to lose weight was measured with the response to a single question, ranging from (1) not to (10) extremely motivated; patients were also requested to rate the degree of social influence on their decisions to seek treatment, on a scale from (1) no influence to (5) strong influence. Readiness to restrict food intake and readiness to increase physical activity were measured on a scale from (1) not ready to (10) trying to change, extrapolated from the Readiness and Motivation Interview [29] and the trans-theoretical model of change [30]. Weight loss goal was measured using one question from the Goals and Relative Weight Questionnaire [31], from which the relative difference (%) between participants’ actual weight before treatment and their goal weight was calculated. A higher percentage indicates a higher expectation of weight loss.

Outcome expectations were operationalised by asking the respondents to “indicate how likely you believe it is that you will feel this way three years after the operation/treatment” on a set of 9 items with scores ranging from (1) no to (10) high expectations. The scale was developed for this study. The factor analysis of the responses yielded two factors: well-being (e.g., satisfied with the amount of weight lost, general appearance, self-esteem, and feeling good about oneself), and social competence (e.g., improved sex life, being outgoing, personal success, and fewer concerns). General perceived self-efficacy, i.e., a strong belief in one’s ability to master new behaviours or situations, was assessed using the 10-item General Perceived Self-efficacy Scale.


The surgical group (n=301) was characterized by their younger age (43.8 vs. 46.2 years, p<0.01), higher percentage of women (79.1 vs. 70.1 %, p<0.05), and higher BMI; 45.0 vs. 41.9, p<0.001). Patients belonging to the surgical group reported a higher frequency of drinking soda (p<0.01), more use of unhealthy weight-reduction methods (p<0.001), and a family history of obesity (p<0.01). In addition, they had a longer history of dieting (p<0.001), participated more often in organized weight loss programmes (p<0.01), and had more often lost >10kg (p<0.01).

Overall, there were few significant group differences regarding self-evaluative and mental health factors. The surgical patients reported a higher level of depressive symptoms (p<0.05) and fewer binge-eating episodes (p<0.01). The surgical group exhibited more dispositional resilience and a realistic life orientation (p<0.01) and structured style (the ability to keep daily routines, to plan, and to organize) (p<0.001), compared to the non-surgical group.

The researchers report that the most notable group differences were that patients opting for bariatric surgery scored higher on factors considered central to initiating and maintaining behaviour change, such as higher general self-efficacy, weight loss goals, and expectations of increased well-being in the future, as a result of the surgery.

“The pretreatment differences in psychological predictors indicate that the results of studies addressing effective behavior change and weight loss maintenance programs for conservative weight loss treatment patients may, with some adjustments, also apply to patients undergoing bariatric surgery,” the researchers write. “…Our findings imply that future research may examine how high outcome goals and expectations interact with depressive symptoms depending on the degree of weight loss throughout the post-operative course.”

The researchers concluded that future studies should explore the effect of interventions for bariatric surgery patients, promoting postoperative physical activity and stress realistic outcome expectations.


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