Body dissatisfaction or a critical preoccupations with one’s own appearance (e.g. muscles) are considered normal to some extent, but when unwanted thoughts, i.e. intrusions, become too excessive or repetitive behavior becomes time-consuming and causes major distress, the diagnosis of body dysmorphic disorder (BDD) needs to be considered. As BDD onset typically occurs during adolescence, it is vital to identify vulnerable populations or settings with a higher prevalence or risk factors at a younger age in order to tailor specific screenings and/or interventions. In some countries military service including an initial physical examination is mandatory for all young men. Thus, the military might strengthen the focus on physical fitness and increase the vulnerability for being preoccupied with body features, especially with one’s owns muscles, making military personnel prone to a special subtype of BDD, the so-called muscle dysmorphia. To date, there is little research on BDD in the military context, therefore the prevalence of symptoms of BDD and associated factors in this specific population is of interest in the following study.
Body dysmorphic disorder
Preoccupation with the appearance is relatively common: In a representative sample of 2552 participants of the general population, 27% percent of the males and 41% of the females reported being preoccupied with the appearance of at least one body part , without meeting all criteria of body dysmorphic disorder (BDD). According to the DSM-5  BDD, describes the preoccupation with one or more «defects or flaws» of one’s own body part(s) or appearance, which are not apparent to others. This perception leads to repetitive and time-consuming behaviors (such as mirror checking, excessive exercising) or mental acts (such as comparing oneself to others) of some sort. These preoccupations may cause severe educational or occupational dysfunction or social isolation but do not meet the diagnostic criteria of an eating disorder. In the DSM-5, BDD is categorized in the obsessive-compulsive-spectrum . BDD is highly associated with comorbidities such as mood or anxiety disorders , and it is associated with a high burden of disease such as impaired psychosocial functioning or high suicide risk. In a prospective study of up to 4 years on 185 patients with BDD, Phillips and Menard  analyzed suicide risk among individuals with BDD: 57.8% of respondents reported suicidal ideation, and 2.6% attempted suicide within one year. Two patients died by suicide throughout the study .
In the DSM 5 there are two specifiers for BDD: One is with or without muscle dysmorphia, the other differs with or without insight. In individuals with muscle dysmorphia the preoccupation is focused on the muscles or the body built . The idea that their body build is too small or insufficiently muscular might lead towards specific dieting (e. g. proteins), or physical activities (e. g. weightlifting) to increase size and definition of the muscles. Also the preoccupations may cause avoidance (e.g. avoiding situations where the body is exposed) or safety behaviors (e.g. giving up social activities to continue with time-consuming work-out). First described in 1993, Pope et al.  conducted a survey to analyze the body images of 108 male body builders; they did not examine BDD or muscle dysmorphia but found something described as a “reverse anorexia” syndrome in nine (8.3%) of the subjects, where the body builders believed that they appeared small and weak even though they were actually tall and muscular. This could be interpreted as a form of muscle dysmorphia.
BDD has prevalence rates ranging from 1.7–2.9% [1, 6] and an overall weighted prevalence in the community of 1.9%  . As a systematic review found slightly higher prevalences for men than for women , some found them to be similar (2.4% vs. 2.2%), but gender differences in the areas of preoccupation have been found (e.g., muscle dysmorphia occurs almost exclusively in males) . Prevalences vary in different samples, such as in student populations (3.3%) or in psychiatric outpatients (5,8%), and the prevalence reached up to 20.1% among patients undergoing rhinoplasty surgery . Point prevalences for muscle dysmorphia are also higher in professional male weightlifters [5, 9].
Gunstad and Phillips  gave an overview of the lifetime axis I comorbidity rates in published studies of BDD; the most common comorbidities using Structured Clinical Interviews for DSM-III-R (SCID-P) were major depression (range: 8–82%), obsessive compulsive disorder (OCD; range: 6–78%), social phobia (range: 12–69%), and substance use disorders (range: 21–36%). Against the background of the range of comorbidities, they examined comorbidities in 293 patients with BDD; the most common comorbidity was major depression (75.5%), followed by social phobia (36.5%), OCD (32.1%) and substance use disorders (alcohol: 20.5%; other drugs: 17.1%). Furthermore, a correlation between the number of comorbid disorders and the functional impairment of a patient was found.
Gender differences in BDD
Phillips, Menard and Fay  analyzed similarities and differences between 63 men and 137 women suffering from BDD. Though their findings lack generalizability (e.g. due to recruitment of sample limited to northeastern United States), the results are still noteworthy. Men suffering from BDD were significantly older, more likely to be single, and more likely to have their own household than women. The age at onset is within adolescence, thus men had an older age at onset than women (M = 17.9, SD = 6.9 vs. M = 15.9, SD = 7.1). Compared to women, the areas of preoccupation among men were more often their genitals (17.5%), body build (36.5%), and thinning hair/balding (36.5%). Men were also obsessed with their jaw (17.5%), nose (38.1%), skin (69.8%), belly (19.0%), and eyes (19.0%), but no differences were found for these areas between men and women . Men were also more likely to have a comorbid substance use disorder than women . Nevertheless, there are few studies focusing on male samples or gender-related research questions.
Symptoms of BDD in the military
The military requires physical and mental fitness, and pursuing a military career may lead to a rather dysfunctional attention to physical fitness. As mentioned above, if preoccupations about the body build being too small or insufficiently muscular lead through specific behavior patterns to distress and impairment, BDD might occur. Also, the age at BDD onset for men (M = 17.9, SD = 6.9) is around the period when the initial test of fitness for the military service takes place. Thus, Campagna and Bowsher  conducted a survey to determine the prevalence of BDD and muscle dysmorphia in enlisted U.S. military personnel. A total of 13% of male and 21.7% of female participants reported body dysmorphic symptoms in this specific sample . Further analysis showed muscle dysmorphia in 12.7% of the males and 4.2% of the females. As this first study only used self-report measure, and given the complexity to distinguish between body dissatisfaction, eating disorders and BDD, the results should be interpreted with caution. The measures used are only screening tools, and shouldn’t be interpreted as prevalence rates of BDD or MD. Still, it shows, that in this population the preoccupations about body dissatisfaction might be high and focused on the body built or muscular size, especially for men. Recent research on the prevalence of BDD and associated features (e.g., depression) lacks in specific samples (e.g. specific professions), which would be necessary to identify settings and populations where there is a high risk of BDD. This study aims to 1. assess the prevalence of BDD symptoms in Swiss military recruits, 2. specify the areas of preoccupation with particular regard to muscle dysmorphia in this sample, and 3. analyze associated features, such as depressive symptoms and alcohol/drug abuse. Due to feasibility, within the probable associated features the focus was set on depressive symptoms and alcohol/drug abuse.