Obesity is turning from a health condition into a public health crisis worldwide.
The prevalence is higher in industrialized and developed nations. In the United States, statistics show that more than 30% of people older than 20 years are obese. But beyond the aesthetics, the main problem of obesity has to do with its comorbidities.
Comorbidities are health problems that usually coexist. For example, high-fat levels in the blood have fat plaque formation (atherosclerosis) as comorbidity.
Obesity has a very long list of comorbidities in almost every body system. In the cardiovascular system, it predisposes to heart attacks and high blood pressure. In the metabolic system, it coexists with type 2 diabetes.
Moreover, in the gastrointestinal tract, being obese increases the risk of acid reflux. In the genitourinary system, many morbidly obese patients also have incontinence.
Urinary incontinence is then counted among the comorbidities of obesity. It is the uncontrollable and unavoidable sensation of voiding. These patients can have either small urine leakages or a large volume depending on the case. This is not only a physical problem. It also bears consequences in the patient’s psychological, social, and working environment.
In this article, we will explore the link between obesity and incontinence. Besides, you will learn how obesity affects other aspects of the genitourinary system and how weight loss can help treat or at least prevent urinary incontinence.
Obesity and incontinence– what’s the link?
Incontinence is more common in men and women. According to one study based on surveys, only 13.9% of male respondents had incontinence. In contrast, 51.1% of women experienced this problem. That is why most studies about incontinence are focused on obese women. Males have similar body structures and similar risk factors, and the exact mechanisms that cause incontinence in obese women may potentially trigger the symptom in men (1).
A recent review gathered all the data about morbid obesity as a risk factor for urinary incontinence (UI). The researchers found a close relationship between overweight and UI symptoms in obese women. The association was extremely tight, and they found a dose-response effect. In other words, as the weight increased, the prevalence of urinary incontinence was higher.
BMI (body mass index) is a reliable measure of obesity in the average population (not athletes because of their muscle mass increase). This number is obtained by dividing the weight in kilograms by the square of the height in meters. In overweight and obesity, the BMI measure reaches 25 or higher. According to studies, for every 5 kg/m2 increase in the BMI, the risk of incontinence increases by 20-70%. The link is so close that one study suggested obesity as the most critical risk factor (1).
Association between obesity and types of incontinence
There was also a difference in the kind of incontinence reported by patients:
- Stress incontinence: It is basically experiencing urinary leaks when you make intra abdominal pressure to laugh, cough, or lift weight. Most patients with overweight and obesity are affected by this type of incontinence, as noted in scientific studies.
- Urge incontinence: It is not related to abdominal pressure, and patients report sudden and unexpected urge to urinate, not associated with any coughing, laughing, or lifting weight. Patients with obesity are not particularly affected by this type of incontinence.
- Mixed incontinence: It is a type of incontinence that includes both stress and urge incontinence symptoms. Overweight and obese patients also suffer from this type.
By only looking at the trend, we can see that something is going on here. Obesity increases the risk of stress-predominant incontinence and not urge incontinence. Stress incontinence is triggered by abdominal pressure, where fat deposits are usually located. When obesity is extreme, the risk of urinary incontinence is very high.
In morbidly obese women who were about to undergo bariatric surgery (weight loss surgery), this symptom affected 60-70% of them. It was a prevalence of 28% stress incontinence, 4% urge incontinence, and 32% mixed incontinence. The association is clear, not only between obesity and incontinence but also regarding the type (1).
It is also interesting to look at the relationship between fat distribution and incontinence. In other words, we already know obesity leads to incontinence. Can we find a relationship with the location of excess weight? It appears so.
Abdominal obesity (fat deposits primarily located in the abdomen) causes more incontinence than other types of obesity. This is measured by waist circumference, which is often measured in studies. One of them showed that every 10 cm increase in waist circumference led to a higher prevalence of this problem (1).
But what exactly happens with abdominal obesity? The exact mechanism is not entirely known, but we have different proposals and theories. Stress incontinence is the most common type, so we hypothesize that obesity increases abdominal pressure.
An increase in abdominal pressure pushes the bladder and increases urethral mobility. This leads to stress urinary incontinence and may also affect the detrusor muscle and cause an overactive bladder.
In this regard, obesity works similarly to pregnancy and causes chronic stretching of the muscles and nerves. They weaken and affect our pelvic floor muscle structure and function. All of these factors contribute to the development of urinary incontinence.
Other authors propose a systemic mechanism as well. Obesity can lead to nerve dysfunction. Either by intervertebral disc herniation or direct nerve damage, obesity could trigger changes in the nervous system that contribute to the problem. Still, the mechanism is not yet clear because many obese women have other conditions that trigger incontinence, such as multiparity, pelvic surgery, or estrogen deficiency (2).
Obesity as a risk factor for prostate cancer
As noted in the introduction of this article, the primary concern of obesity is related to its comorbidities. They are diseases associated with obesity and sometimes triggered by excess fat. The number of comorbidities is very high, and two of them are very important in the male genitourinary system. They are urinary incontinence and prostate cancer.
According to studies, the incidence of prostate cancer increases in obese patients. This increase is modest but consistent in most studies. According to a meta-analysis of scientific data, the relative risk increases by 1.01 for every 1 kg/m2 increase in the BMI and weight gain. For every 5 kg/m2 of BMI increase, the relative risk increases by 1.03. So, there’s also a dose-response between obesity and prostate cancer risk (3).
However, in this case, individual studies have differences from one another. Some studies suggest no particular difference between obese and non-obese groups. Others show a significant difference in risks. When looking at their geographic location, a pattern starts to arise. North American studies usually find no significant impact on prostate cancer rates. European and Australian studies usually report higher prostate cancer rates among obese people.
Why is that? It is probably not because of cultural factors or genetics. It is because every country has different ways to screen for prostate cancer. In the United States, PSA screening is more common. These patients are diagnosed at an early stage with low risk. In Europe and Australia, PSA screening is not widespread and standardized. Prostate cancer screening is sometimes done when the disease has reached an advanced stage.
Moreover, obesity causes a reduction of PSA levels. So, if your country’s protocols only rely on PSA levels to decide when to perform a prostate biopsy, there’s a chance that obese people get the diagnosis at a very advanced stage. That’s one of the reasons why obesity is related to advanced prostate cancer. But it is not the only one. There are also biological mechanisms (3):
Changes in the insulin/IGF-1 axis
Insulin is one of the problems of overeating, eating sweets, and processed foods. When insulin levels increase after eating, they accelerate tumor growth. Many tumors have an insulin receptor that becomes activated every time we overeat or eat sweets. As such, insulin peaks become fuel for cancer. This phenomenon is evident in all types of cancer, including that of the prostate gland. Insulin level increase is associated with higher mortality for prostate cancer. In contrast, when type 2 diabetes patients use metformin, a drug that reduces their insulin levels, their risk of prostate cancer reduces dramatically. Similarly, when insulin levels decline in advanced diabetes, the risk of prostate cancer reduces as well.
Another bioactive molecule is IGF-1 (Insulin-like growth factor 1). This substance is similar to insulin and also stimulates growth in tissues. When elevated, IGF-1 stimulates tumors and promotes cancer in the prostate. Obese patients usually have an increase of IGF-1, and their risk of prostate cancer aggressiveness is higher. What IGF-1 does is taking prostate cancer cells and making them independent of androgens. They no longer need androgens to divide and keep on growing. Thus, they are more aggressive and turn into castrate-resistant prostate cancer.
Sex hormone changes
In obese patients, we also have several changes in their sex hormones. Studies show that low testosterone levels increase the aggressiveness of prostate cancer. As the levels of testosterone decrease in seniors, the aggressiveness of cancer increases. But low testosterone is not only a companion of prostate cancer in this stage. It actually has a role in making cancer more aggressive. In clinical trials using 5-alpha reductase inhibitors to prevent prostate cancer, cancer risk decreased, but the Gleason score increased. In other words, the number of cases reduced, but cancer was more aggressive than usual.
In obesity, testosterone is replaced by estradiol in the adipose tissue. The more fatty tissue a man has, the more testosterone gets replaced by estradiol. Low testosterone levels and high estradiol levels in a man can also contribute to prostate cancer development and progression.
Fatty tissue and adipokine modulation
Another mechanism has to do with inflammation. Obesity is a systemic health condition, and it causes inflammation in every cell of the body. Substances released by adipocytes trigger this inflammation. They are called adipokines. Cancer cells use inflammation to obtain more blood and nutrients. Thus, obesity would indirectly feed cancer cells, including those located in the prostate. Interleukin-6 (IL-6) levels are increased in patients with obesity. Prostate cancer cells have receptors to IL-6, and they apparently make cancer more aggressive. Elevated IL-6 levels are related to a higher risk of metastatic prostate cancer.
An increase in periprostatic adipose tissue
There is fatty tissue around the prostate. It is called periprostatic adipose tissue. According to studies, an increase in periprostatic adipose tissue is associated with a higher risk of prostate cancer. It is apparently because this adipose tissue is a source of IL-6 and other cytokines. They promote cancer development and make cancer cells more aggressive. In any case, patients with obesity have an increase of fatty tissue around the prostate. This is associated with a higher Gleason grade and a risk of metastatic disease.
Impact of Obesity on Long-Term Urinary Incontinence
Urinary incontinence is not very common in men. It is more prevalent in women. But one of the triggers of incontinence in men is radical prostatectomy. This procedure is usually done to take out prostate cancer. It is also helpful if you have benign prostate hyperplasia and very severe urinary symptoms. However, some patients end up with urinary incontinence shortly after surgery.
The prostate is located in the bladder neck. Thus, by removing the prostate, your surgeon will also stretch the bladder. If you have additional risk factors for urinary incontinence, it could be triggered. One of these risk factors is being obese.
Obese patients are at a higher risk to suffer from urinary incontinence after prostate surgery. They also have a higher incidence and severity of lower urinary tract symptoms (LUTS). Urinary incontinence is usually a temporary problem after surgery, but obese men take more time to recover. They sometimes have long-term urinary incontinence and may not fully recover at all. According to a recent meta-analysis, this association was made evident in 1 and 2 years after prostate surgery. BMI changes did not alter Early-onset urinary incontinence. In other words, men will have a similar risk of urinary incontinence, but when they are obese, this problem will be maintained for a very long time.
Obesity before surgery led to urinary incontinence that was not solved after 1 and 2 years. The surgical technique also has a role. Laparoscopic Radical Prostatectomy (LRP) patients usually recover their normal urinary function after two years. But when Robotic-Assisted Laparoscopic Radical Prostatectomy (RLRP) was performed, obese patients were more likely to experience urinary incontinence for 24 months or more (4).
In a nutshell, you’re likely to have long-term incontinence after a radical prostatectomy if you’re obese, and it is wise to consider with your doctor the possibility of using LRP instead of RLRP in this case. This technique apparently carries a lower risk of long-term urinary incontinence.
Prevention of Urinary Incontinence
Obesity is a risk factor for urinary incontinence, and that’s for sure. It is a modifiable risk factor, which means we can do something about it. It is not like genetics and aging. If that’s the case, weight loss should be adequate to treat or at least prevent this problem.
Clinical experience shows that bariatric surgery improves incontinence. Even a slight weight loss bears a significant difference. Losing 5% of your weight may reduce incontinence frequency by 50%. Moreover, the benefits are kept for a very long time. After 6 months, patients still experience improvements (5).
Lifestyle changes to lose weight are useful to prevent and treat urinary incontinence, too. According to clinical trials, diet and exercise for six months caused a weight reduction of 8%. These patients also had a drop of weekly incontinence episodes by 47%. The incontinence rate is still lower if we take out smoking and other risk factors (6).
We can also take these measures to reduce the incidence and severity of incontinence episodes:
- Diabetes control: High blood glucose increases the urinary output and worsens incontinence. Inadequate control in diabetic patients may also lead to nerve problems and an overactive bladder. Thus, it is wise to maintain glucose levels under control if you want to avoid incontinence.
- Pelvic floor exercises: Pelvic floor muscle training before surgery can be appropriate to prevent stress incontinence. This is particularly useful in pregnant women before labor and a C-section. They are prone to pelvic floor disorders afterward. Pelvic floor training has short-term benefits, which also apply to any pelvic floor procedure.
- Smoking cessation: We already mentioned smoking cessation, but it is essential to highlight its importance here. Smoking irritates the lower urinary tract and predisposes to urinary incontinence symptoms. If you stop smoking, you will prevent or improve cases of overactive bladder and urgency incontinence. Some patients with stress urinary incontinence may also report improvements after smoking cessation.