Adherence of Reporting Energy Intake by a Novel Food Photo Recognition Dietary Assessment App on Morbid Obese Subjects Scheduled for Bariatric Surgery

Introduction

Obesity is one of the most important public health conditions worldwide. The morbidity can largely reduce life expectancy. Bariatric surgery for severe obesity is an effective treatment that results in the improvement and remission of many obesity-related comorbidities, cardiovascular benefits, as well as sustained weight loss and improvement in quality of life. Different surgical procedures for weight loss have been developed, with the most common ones being sleeve gastrectomy (SG) and Roux-en-Y Gastric Bypass (RYGB). RYGB is the most commonly used procedure for weight loss in Switzerland, even though in the last decades there has been a global shift towards SG. Independently from the applied procedure, bariatric surgery remains the most effective and durable intervention for obesity. Modern bariatric surgery has an excellent safety profile, even though complications in the short and long term have been reported. Extensive research also increased the understanding of the wide range of mechanisms underlying the effectiveness of bariatric surgery. The relative contributions of these mechanisms vary according to the chosen procedure, where altered satiety and hunger are considered important factors after RYGB. Other mechanisms have also been proposed, including changes in gut hormones, reduced appetite, increased satiation, increased energy expenditure, alteration in the gut microbiota and bile acids levels and composition, as well as changes in vagal nerve signalling. Changes in food preferences have also been implicated as an important candidate mechanism as patients prefer low-sugar low-fat food and report finding food, in general, less enjoyable after RYGB. Both humans and rats eat less and display altered food preferences after RYGB, but the underlying behavioural mechanism remains unclear.

The aim of public health policy in the treatment of obesity should be the development of effective prevention and better therapies which would eliminate the need for surgery altogether. Until then, bariatric surgery is safe, effective, affordable, and with large room for improvement. Furthermore, a deeper understanding of the physiological changes underlying the improvement of the morbidity may help in developing new therapies. So far, direct measurements of changes in food selection in humans after RYGB have been limited by the unreliability of patients, which poses significant methodological and conceptual challenges to researchers and study design . Self-monitoring requires time and effort, and many find tracking of dietary intake tedious, which contributes to attrition . Direct measurements, however, represent an essential component in the attempt to understand how RYGB alters eating and food preferences, but laboratory settings preclude a real-life environment. Consequently, obesity researchers have attempted to develop new easier tracking methods such as photography of food items to monitor dietary intake both in the clinical setting and everyday life. These new methods seem more effective compared to others. For instance, mobile phone applications of photographic food recognition (PFR) such as SNAQ enable patients to record and submit consumed food items, portion sizes and frequency of consumption during a pre-defined period. However, this technology is still in its infancy and assessment procedures need to be validated by trained professionals. The doubly labeled water (DLW) method has been proposed as a gold standard to assess free-living total energy expenditure and can be used to monitor the body composition (BC) and total energy expenditure (TEE) of an individual under circumstances of energy balance based on dilution equations of the labelled isotopic elements in the body . Direct segmental multifrequency bioelectrical impedance analysis (DSM-BIA) is considered a practical, non-invasive, and relatively inexpensive method to quickly assess the BC27 and the estimations of BC with DSM-BIA are reported to be consistent with those of the DLW method also for obese patients. The joint measurement of TEE using the estimations of the PFR and the DLW method would serve the validation of PFR for the measurement of TEE in patients undergoing RYGB. PFR would become then a powerful tool for research and provide useful information for the design of appropriate individualized obesity treatment programs.

Research question

The aim of this study is to investigate changes in food preferences, total energy intake of the three primary macronutrients and meal patterns between obese women (BMI ≥ 35) before and after Roux-en-Y gastric bypass and lean (BMI ≤ 25) and obese (BMI ≥ 35) controls by means of PFR with the mobile application SNAQ.