**1. Introduction**

In March 2020, the World Health Organization declared the spread of the novel coronavirus a worldwide pandemic [1]. Until then, obesity had long been named the worst pandemic of the 21st century and caused more deaths than being underweight worldwide [2]. Since 1975, the prevalence of obesity nearly tripled [2]. Six hundred fiftynine million adults (18 years and older) were obese in 2017, leading to over 4 million overweight-related deaths, according to the global burden of disease report [3]. Recent studies on COVID-19 showed that obesity worsens the outcome from COVID-19 [4] and that mortality increases as a function of the body mass index (BMI) [5–8], thus making people suffering from obesity highly at risk for a severe course of disease.

Obese individuals are known to suffer more often than normal-weight controls from a variety of mental comorbidities such as depression, anxiety disorders or eating disorders, and reduced health-related quality of life [9–12]. A bi-directional link of obesity and depression can be found throughout various studies, showing that obese patients are more depressed and vice versa [13]. Emotional distress and impaired self-management

may lead to a loss of structure and a relapse into old behavioral patterns, eventually resulting in weight gain [14]. Additionally, heightened mental stress and problems in emotion regulation trigger impulsive eating symptoms such as binge eating and purging behavior [15,16]. This makes the group of patients suffering from obesity at high risk for elevated levels of psychological burden. Recent studies show the COVID-19 pandemic put a high mental strain not only on the general population but even more so on already psychologically burdened individuals. Patients suffering from obesity seem to be even more at risk for COVID-19-associated psychological burden [17,18]. A retrospective medical chart review showed that since stay-at-home orders were initiated because of the COVID-19 pandemic, patients with obesity reported increased anxiety and depression regardless of infection status [19]. Another study showed that people with obesity had a significant increase in weight, BMI, and changes in the eating psychopathology during the COVID-19 pandemic [20]. These findings not only underlined obese individuals' risk of various somatic and psychological comorbidities, but also suggested a high-risk status in the current COVID-19-pandemic.

In Western countries, obesity surgery is the most common treatment for patients with BMI ≥ 40 kg/m<sup>2</sup> or BMI ≥ 35 kg/m<sup>2</sup> who also suffer from obesity-related comorbidities and did not respond to behavioral treatment, exercises, and nutritional treatment [21,22]. A recent RCT found that obesity surgery candidates seem to suffer from equally elevated levels of depression as psychotherapy inpatients, making this group also prone to heightened psychological strain during the current pandemic [23]. Findings from before the COVID-19 pandemic showed that for most of these patients, mental health improves after obesity surgery even if the mechanism and the psychological factors remain unclear [24,25]. Although dysfunctional eating behaviors decreased directly after obesity surgery between the first and third year after the intervention, dysfunctional eating behavior significantly increases again [26]. Weight loss as a result of obesity surgery does not mean an improvement in mental health at the same time, as the expectations of a life-changing measure can be exaggerated and frustrating [27].

Literature is lacking on the impact of obesity surgery in obese individuals concerning eating behavior and the psychological distress during the COVID-19 pandemic. Restrictions in social life due to quarantine measures, physical distancing, and COVID-19-related fear may pose a special burden for this vulnerable patient group. The aim of the current study was to investigate to what extent obesity surgery affects COVID-19-related eating behavior, generalized anxiety, depression, and psychological distress. It is hypothesized that obesity surgery significantly affects dysfunctional eating behavior, bulimic eating behavior, anxiety, and depression during the current COVID-19 pandemic. More precisely, patients probably suffer less from dysfunctional COVID-19-specific eating behaviors, anxiety, and depression after they obtained an obesity surgery compared to a group of obese people that are still awaiting such a surgical measure.
