Associations between diet composition, dietary pattern, and weight outcomes after bariatric surgery: a systematic review.

INTRODUCTION: Literature describing the impact of dietary intake on weight outcomes after bariatric surgery has not been synthesized. This study aimed to synthesize the evidence regarding any association between diet composition and weight outcomes post-bariatric surgery. METHODS: CINAHL, Cochrane, Embase, MEDLINE and Scopus were searched for adult studies up to June 2021 that assessed any association between dietary intakes (≥1-macronutrient, food group, or dietary pattern) and weight outcomes at 12-months or longer after bariatric surgery. Risk of bias and quality assessments were conducted using the Scottish Intercollegiate Guidelines Network checklists and the NHMRC's Level of Evidence and Grades for Recommendations. Study findings were presented according to the time of post-surgery dietary intake assessment (≤12months, between 12 and 24 months, ≥24months). RESULTS: 5923 articles were identified, 260 were retrieved for full text screening, and 36 were eligible for inclusion (9 interventional including five randomized-controlled trials, and 27 observational cohort studies; sample sizes: 20-1610; total sample: 5065; follow-up periods: 1 year-12 years; level of evidence: II to IV, risk of bias: low to high). Findings on the association between long-term weight outcomes and dietary composition up to 24-months were mixed. After 24-months, studies consistently suggested no significant associations between weight loss and macronutrient composition or core food group patterns, or between carbohydrate, protein or food group patterns and weight recurrence. A single cohort study reported a weak association between diet quality score and weight-recurrence after 24-months. CONCLUSION: There was no strong evidence to support significant associations between diet composition and weight outcomes post-bariatric surgery. The heterogeneity in study design and quality may reduce generalizability to external populations. Individualized dietary recommendations may be useful to support long-term post-surgery weight outcomes. More studies are needed to define and measure diet quality in this patient cohort. REGISTRATION: PROSPERO (CRD42021264120).

Psychopathology and eating behaviour in people with type 2 diabetes referred for bariatric surgery.

PURPOSE: Psychopathology and disordered eating behaviours are putative pre-operative risk factors for suboptimal outcomes post-bariatric surgery. Documented psychopathology prevalence rates vary in bariatric candidate samples. Further, less attention has been paid to vulnerable subgroups such as people with diabetes who might be at an elevated risk. For these reasons, this study aimed to investigate the rates of psychopathology and disordered eating in pre-surgical candidates with type 2 diabetes mellitus (T2DM). METHODS: Participants were 401 consecutive patients from a state-wide bariatric surgery service for people with T2DM. Psychopathology was measured using multi-modal assessment including diagnostic interview and battery of validated questionnaires. The mean age of the sample was 51 years with a mean BMI of 46 kg/m2. The majority of the sample was female (60.6%), born in Australia (87%) and 18.2% identified as Aboriginal and/or Torres Strait Islander. RESULTS: Rates of current psychopathology in this sample included: major depressive disorder (MDD; 16.75%), generalised anxiety disorder (GAD; 20.25%), insomnia (17.75%) and binge eating disorder (BED; 10.75%). There were no significant differences on measures between people who endorsed Aboriginal and/or Torres Strait Islander status compared to those who did not endorse. The mean total score on the BES was 21.82 ± 10.40 (range 0-39), with 8.2% of participants meeting criteria for severe binge eating. Presence of an eating disorder was not significantly associated with degree of glycemic compensation. Average emotional eating scores were significantly higher in this study, compared to reference samples. Significantly increased binge eating severity and emotional eating severity was revealed for people with T2DM and comorbid MDD, social anxiety and eating disorders. Binge eating severity was associated with GAD, food addiction, substance use disorders, and history of suicide attempt but not emotional eating severity. CONCLUSION: Amongst people with T2DM seeking bariatric surgery, MDD, GAD and emotional eating were common. Psychopathology in a sample of people with T2DM seeking bariatric surgery was significantly associated with severity of disordered eating. These findings suggest people with T2DM seeking bariatric surgery may be vulnerable to psychopathology and disordered eating with implications for early identification and intervention. LEVEL OF EVIDENCE: Evidence obtained from cohort or case-control analytic studies.

Psychosocial presentation of revisional LAGB patients: a qualitative study.

This qualitative study offers insight into the experiences, expectations, perceptions and beliefs that may lead to laparoscopic adjustable gastric band patients' failure to achieve expected weight loss and seek revisional bariatric surgery. The 23 participants from two sites were interviewed and data were analysed from a grounded theory methodology in order to build a causal model. Analysis of participants' reports identified 'unrealistic expectations of the LAGB' as the core category. Additionally, the restriction of the band had a negative impact on participants' social interactions, leading to feelings of deprivation and, thus, to a desire for reward from food choices and consequently an increase of consumption of high-calorie-dense foods. These foods were chosen because of their specific texture or ability to provide reward. The resulting increase in weight or failure to achieve excess weight loss, led to feelings of shame and loneliness and emotional eating resulting in increased the consumption of rewarding foods. Thus, identifying unrealistic expectations of laparoscopic adjustable gastric band (LAGB) and emotional eating behaviours are important in those who are present initially for primary bariatric and revisional bariatric surgery, as they may contribute specifically to these patients' weight regain and consequent failure to achieve excess weight loss.