Obesity is one of the world`s most serious public health problems. Conservative weight reduction methods alone (diet, exercise) often show disappointing results, as the majority of people who lose weight regain it after a shorter or longer period of time. The currently most effective measure to achieve a durable weight-loss is bariatric surgery.When investigating the effectiveness of bariatric surgery, the focus has most often been on weight loss and obesity-related complications, while effects on social interaction and subjective experience have received much less attention (for reviews, see (Broadhead et al., 1983; Uchino, 2006). A large body of evidence has demonstrated that (supportive) social relationships benefit health. Most strikingly, individuals with low compared to those with high levels of social connectedness are more likely to die prematurely. Social relationships can also affect a range of other health conditions such as cardiovascular disease, cancer, and immune function e.g. (Umberson & Montez, 2010). However, individuals with obesity may experience social interactions as less positive than normal-weight individuals. They recount avoiding social events and relationships, but also career opportunities, shopping and other activities where they feel observed (Hughes & Degher, 1993; Maphis et al., 2013; Rosen et al., 1991) because of weight stigma. Such avoidance behaviour can lead to a “chronic disengagement” with many aspects of social life, which in turn might decrease interpersonal skills (Major & Schmader, 1998). Further investigations into the link between social behaviour and eating found that greater emotional eating is associated with greater social avoidance (Brytek-Matera et al., 2018). Eating was described a means to cope with loneliness on the one hand, while on the other hand aggravating feelings of being alone due to the stigma associated with obesity (SARLIO-LAHTEENKORVA, 1998). This way, loneliness and obesity can create a vicious circle. Only a few studies have investigated how bariatric surgery influences social interactions. One 10-year follow up study found improvements in social interactions for bariatric surgery, but not for conventional weight loss treatment (Karlsson et al., 2007). In qualitative studies, many participants mentioned that they received more positive social feedback following bariatric surgery (Lyons et al., 2014), and also that they enjoyed social activities more than before (Stolzenberger et al., 2013), although they also describe ambiguous feelings (Coulman et al., 2017). This conforms also to reports from our patients at Vestfold Hospital Trust. In the present study, we aim to investigate whether and how two types of bariatric surgery improve the response to a range of social aspects of patients’ daily lives. We further aim to determine potential mechanisms leading to these effects, namely changes in body image, gut hormones, and reward responsivity.
