Sexual Dysfunctions in Obesity
Obesity is an increasing global epidemic leading to short- and long-term complications and much comorbidity. Sexual dysfunctions are often associated with obesity and represent a major cause of psychological suffering. However, clinicians seem to ignore and misdiagnose sexuality when they approach patients with obesity. The aim of this chapter was to update and review the state of knowledge on the relationship between obesity and sexual dysfunction. The possible links were discussed highlighting putative mediating factors such as biological and hormonal aspects, gender difference, and medical and psychiatric comorbidities. In conclusion, deepening the comprehension of the rationale for sexual disorders in obesity may help the advances in the obesity treatments and improve patients’ quality of life.
10.1 The Burden of Sexual Dysfunctions in Obesity
The worldwide prevalence of obesity has dramatically increased from 6.4% in 1980 to 12.0% in 2008. Half of this rise occurred in the last 15 years . It was estimated that almost 1.5 billion individuals were overweight in 2015 . Data from the European Health Interview Survey (EHIS), which was conducted between 2013 and 2015, had shown that among European Union, above 50% of the adult population was calculated as overweight or obese .
Therefore, obesity is an increasing global epidemic leading to short- and long-term complications impacting subjective well-being, physical health, mental health, and quality of life. The majority of patients with obesity show an impaired quality of life in respect to the general population, irrespective of their psychological suffering. The construct of quality of life is multidimensional and can be considered as an “umbrella term” that includes either medical or psychological issues. In particular, sexual dysfunctions are critically related to the quality of life and represent a topic of growing interest in the obesity field. In individuals with severe obesity (body mass index > 35 kg/m2), sexual dysfunctions have been reported with a prevalence rate of 7–22% in women and 5–21% in men . The real diffusion of sexual disorders could even be higher given that clinicians often do not ask and underestimate their prevalence as much as the repercussions on the patient’s quality of life. Sexuality is often a disregarded issue by mental health practitioners; some psychiatrists may be not sufficiently trained about this topic, and they can feel embarrassed and uncomfortable with the theme . In contrast, most patients, when asked, are encouraged to discuss sexual problems finding that discussion helpful.
Recent data from a multicenter large cohort study reported that during the month prior the clinical assessment, one third of women and a quarter of men with extreme obesity were not sexually active, alone, or with a partner. Moreover 49% of women and 54% of men were found with moderate to high level of sexual dissatisfaction .
The relationship between obesity and sexual dysfunction is complex and multidimensional with many aspects playing a role, such as biological and hormonal factors, gender differences, medical comorbidities, and psychosocial issues.
10.1.1 Neurobiological Factors
Existing research highlighted that eating and sex shared common underlying brain representations. In fact, the same hypothalamic areas of the limbic system were found to influence feeding and sexuality.
As for libido and coitus components of sexuality, eating is made of a motivational factor that is hunger and a consummatory part with rhythmicity that is the alimentation .
The orbitofrontal cortex is implicated in the encoding of sex and food representations with associations of positive or negative judgment. The insula, the anterior cingulate cortex, and the amygdala ventral striatum are engaged in the phases of anticipation, consummation, and satiety in both sexuality and alimentation . Moreover, eating and sexual functioning are similar in terms of neurotransmission as the case of dopamine system. Numerous neurotransmitters are implicated in sexual desire and behaviors, with dopamine playing a crucial role in the neural reward pathways and emotionally regulated limbic system neural circuits . Behind the homeostatic hunger, palatable food is consumed for its hedonic properties. Such hedonic hunger may lead to an exceeding caloric intake and weight gain. According to a promising research line about the etiology of obesity, reward mechanisms after food intake are related to dopamine transmission in the mesolimbic pathway and to the expression of dopamine D2 receptors (D2Rs) in the nucleus striatum, as demonstrated in the rodent experimental model. In particular, overconsumption of palatable food may weaken the mesolimbic dopamine neurotransmission by reducing the expression of striatal D2Rs which in turns lead to a lower responsiveness of brain reward systems. In obese rats, a significant impairment of dopaminergic transmission in brain circuits has been observed .
These findings have been confirmed in a clinical study on human subjects, showing that the dopaminergic alterations and the consequent drop of the reward hedonic mechanism could determine a vicious circle producing hyperphagia .
Taken together, these researches support the hypothesis for a dopaminergic signaling that regulates consummatory aspects of sexual and feeding behavior.
10.1.2 Reproductive Hormones
The levels of testosterone and its carrier protein, sex hormone-binding globulin (SHBG), decrease as BMI increases, particularly in men with abdominal obesity (waist circumference >102 cm, waists-to-hip ratio >0.9, or BMI >30) . In men with obesity, the decreased testosterone levels range from 20% to 64% of the patients, depending on the characteristics of the population, the age, and on whether total or free circulating testosterone was measured .
Testosterone is the leading sex hormone in men, and it plays a crucial role either in libido or in sexual functioning. Lower testosterone levels can contribute to impaired sexual desire. Androgen deficiency can directly affect erectile dysfunction. Despite the clear association between obesity and low testosterone levels, the causal directionality of this observed link is still uncertain.
Low testosterone levels in obese men have been associated with increased estrogen production by the adipose tissue, insulin resistance, and low-grade systemic inflammatory process (C-reactive protein values). Leptin levels are higher individuals with obesity and negatively correlate with testosterone values; thus, the excess of circulating leptin may play an important role in the development of decreased androgens in male obesity . Sleep apnea, which is a common comorbidity of obesity, has been associated with decreased testosterone levels . It is noteworthy that although the decrease of testosterone level, in men with obesity, the exogenous testosterone replacement is not found to be an effective treatment for erectile dysfunctions . In fact, among men with obesity, lifestyle interventions aimed at removing the multiple metabolic risk factors of erectile dysfunctions seem to be the most favorable approach. In obese women the excess body weight is associated with an elevation of androgens and estradiol leading to amenorrhea, irregular menstrual cycles, polycystic ovarian syndrome, infertility, preterm labor, miscarriage, and failed fertility treatments . Moreover, weight loss improves female reproductive and sexual health . But, as discussed above, in obese women sexual dysfunctions are more affected by psychological aspects respect to men.
10.1.3 Gender Differences
Gender is a leading determinant of physical and mental health and prejudices individuals’ access to health service. Accordingly, it has been demonstrated that females were more likely to consult a mental health specialist when it was needed . In particular, some researchers brought out that men were less inclined than women to receive medical counseling for sexual dysfunctions [20, 21]. Accordingly, in clinical studies, female sexual disorders are more prevalent compared to population studies.
Moreover, fat storage and metabolism differed considerably between men and women , and gender plays a role in the efficacy of weight-loss treatments either nonsurgical or surgical [23, 24]. Thus, it is reasonable that the relationship between obesity and sexual functioning may be sex specific. Although many researchers investigated sexual dysfunctions in individuals with eating disorders , the literature about gender differences in sexual dysfunctions in those with obesity is still lacking.
Factors that are involved in the relationship between sexual dysfunctions and obesity such as hormones, psychiatric and somatic comorbidities, and the use of medications are all issues that are influenced by gender differences. It is widely recognized that men and women show different response to pharmacotherapies in terms of efficacy and side effects . In women with obesity, sexual disorders seem to be more related to the motivational interface of sexuality, that is, the libido, and studies reported higher rate of psychiatric concerns compared to men as body image dissatisfaction, trauma-related disorders, depression, and eating disorders. On the other hand, in men, sexual dysfunctions are more likely to be attributed to somatic comorbidities of obesity .
Up to one third of patients with morbid obesity had a lifetime history of any substance use disorder, including alcohol abuse, and men seemed to be more vulnerable to alcohol-related disorders .
It was argued that obese women were less sexually active than those with normal weight . In fact, sexual functioning was documented as poorer in obese women, with a more serious impairment in the case of a comorbid binge eating disorder [30, 31].
However, a higher body mass index was not associated with a lower frequency of heterosexual intercourse, and overweight and obese women were more likely than non-obese women to address ever having any sexual relationship with men . An European survey reported high number of unintended pregnancies in obese women . As for the women, normal-weight men indicated ten more lifetime partners than obese men .
Another relevant issue is that gender may influence the doctor-patient relationship, peculiarly in the field of weight-loss counseling. Patients may experience different emotions according to the gender of clinician, which in turn may compromise the adherence to treatment . At similar body mass index, physicians seem to be more prone to promote weight loss in women pointing out possible weight concerns .
Self-report instruments assessing sexual dysfunctions
The Female Sexual Function Index (FSFI) is a 19-item self-report questionnaire that assesses sexual functioning in the past 6 months across six domains: sexual desire, sexual arousal, lubrication, orgasm, satisfaction, and pain during sexual intercourse
The Sexual Quality of Life-Female questionnaire (SQoL-F) is an 18-item self-report questionnaire assessing the impact of sexual dysfunction on a woman’s sexual quality of life. Each question is scored on a six-point scale ranging from completely agree to completely disagree. A higher total score reflects a better sexual quality of life
The Brief Sexual Function Inventory (BSFI) is 11-item self-report questionnaire that measures sexual function in males covering five aspects: sexual drive, erection, ejaculation, perception of problems with sexual function in each of these areas, and overall satisfaction
The International Index of Erectile Function (IIEF) is a 15-item self-report questionnaire assessing erectile dysfunctions exploring five domains: erectile function, orgasmic function, sexual desire, intercourse satisfaction, and overall satisfaction
10.1.4 Medical Comorbidities
Indirectly, obesity may cause sexual dysfunction through the effect of medical comorbidities, namely, high blood pressure, diabetes, and high cholesterol levels. In erectile dysfunctions, lipid disorders and hypertension may cause atherosclerotic damage of penile arteries leading to reduced blood flow in and out of the penis and compromised beginning and maintenance of erection . A reduced blood flow of the vagina may similarly affect sexual arousal in women. Furthermore, symptoms of headache, fatigue, low energy, tiredness, and general weakness that may occur with hypertension affect sexual functioning.
A large body of evidences demonstrated a chronic pro-inflammatory state in obesity, influencing endothelial functioning and contributing to the increased risk of thrombotic accidents . In particular, high levels of pro-inflammatory interleukin (IL)-1β, IL-6, IL-8, tumor necrosis factor-α, and C-reactive protein were found . Whereas it is widely accepted that erectile dysfunction and atherosclerosis share common vascular mechanisms, a diagnosis of erectile dysfunction may represent an alarm of the risk to develop coronary heart disease.
Moreover, although up to 50% of erectile dysfunctions may be ascribed to hypertension and cardiovascular diseases, the activitiy of many antihypertensive drugs may itself undermine erection .
Almost half of men with diabetes experienced sexual dysfunctions with an earlier onset of 10–15 years than nondiabetic population . The limited number of findings about sexual disorders in women with diabetes has documented problems in vaginal lubrication and sexual desire .
Insulin resistance is highly prevalent in obese individuals. The insulin-resistant, hyperinsulinemic state has been associated with a heightened endothelial vasoconstriction, which may possibly contribute to the impaired erection . The usage of diabetic agents, such as metformin and the thiazolidinedione, is not without risks and potential sexual side effects .
10.1.5 Psychosocial Factors
Obesity may be associated with an open range of psychological issues that may affect sexual functioning. Major depression is highly prevalent in persons with morbid obesity representing the leading cause of mental health suffering . Up to up to 78% of individuals with depression treated with antidepressants suffer from a sexual dysfunction . The low self-esteem, fatigue, and the diminished libido characterizing atypical depression may be some of the mediating factors contributing to the link between obesity and sexual function in both men and women. However, despite obesity and depression are often in comoridity, it is virtually impossible to establish if depression or obesity may be the first trigger for sexual dysfunctions. Moreover, many antidepressant drugs are frequently correlated with the onset of sexual dysfunctions .
Body image dissatisfaction is prevalent in patients with obesity, with almost 74% of individuals reporting some distress and concerns about one’s own body. Moreover, body image was estimated as poorer in morbid obese individuals seeking surgical treatment comparing to participants in weight-loss programs and nonobese controls with various gender differences [52, 53]. Since adolescent women developed a cognitive vulnerability to body image disturbances, it may reinforce in adulthood with weight gain and obesity . In a survey of obese men and women, body dissatisfaction was found to be increased in women, with men easily describing themselves as stronger rather than fat .
Body dissatisfaction can inhibit intimate relationship particularly the sexual intercourses. Women satisfied with their body image reported more numerous and pleasant sexual experiences, a broader range of sexual activities with no preoccupations of being sexually undesirable and naked .
The widespread cultural belief that obese individuals are lacking of the willingness to lose weight makes such patients poorly accepted from society leading to problematic and exiguous relationships. In addition, it has been documented that obese individuals often reported a lifetime history of discrimination, stigma, and self-stigma due to their physical appearance . During childhood people with obesity were frequently victim of bullying  that represents a traumatic experience with negative lifelong consequence in peer, romantic, and sexual adult relationships.
Another psychiatric aspect that may play a role in the interface between obesity and sexuality is the field of eating disorder. Among people with obesity, eating patterns may be different from those developing in normal-weight individuals. As discussed above, traumatic events and stigma are two factors influencing relationships that are highly prevalent in obesity. Furthermore, while one who suffers from eating disorder might hide the problem from society, people with obesity are suspected from others as suffering from a problematic eating behavior with a potential stigma effect. Emotional eating is a maladaptive eating behavior that was described as “the tendency to eat in response to emotional distress (i.e. a range of negative, and for some authors positive, emotions) and during stressful life situations.” Eating emotionally is related to binge eating and other problematic eating behaviors like grazing, nibbling, and “uncontrolled” eating which are prevalent in obese individuals . Moreover, the endogenous opioid system was found to regulate emotional eating and sexuality , and it has been associated with impaired sexual desire, arousal, lubrication, orgasm, and satisfaction in women .
In conclusion, sexual dysfunctions are common and critical disorders affecting individuals with severe obesity, leading to considerable psychological distress and impaired quality of life.
Sexuality is warranted to be clearly addressed by clinicians with open and specific questions in the initial screening and during counseling performed with the weight-loss programs. Particular attention is a big demand for gender differences.
Deepening the comprehension and consideration of the suffering of obese individuals with sexual disorders may lead to advances in the obesity treatments and improvement of well-being and quality of life.
Moreover, calling the attention on the advantages of weight loss, some individuals may be more confident with the policy of treatments.
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