Obesity and Urinary Incontinence

By Sarah Hamilton, MD

Originally appeared in the October, 2011 issue of Quality Care®

Being heavy is common in the U.S. A recent Gallup-Healthways Well-Being Index revealed that 63.1% of adults in the U.S. were either overweight or obese in 2009. Being overweight is measured by a body mass index or BMI  >25 kg/m2 (BMI is calculated by dividing weight in kg by height in m2). According to the BMI, a 5 foot 5 inch woman who weighs 150lbs is considered overweight and a 6 foot man who weighs 184lbs is overweight. BMI cannot differentiate between lean muscle mass and fat. Another way to screen for possible health risks is measuring a person’s waist circumference. The risk of heart disease and type 2 diabetes increases if a woman’s waist size is larger than 35 inches and if a man’s waist is larger than 40 inches. There are many reasons to lose weight and we can add one more reason to the list: being overweight is associated with a higher risk of urinary leakage.

There are three main types of urinary leakage or incontinence: stress urinary incontinence, urgency urinary incontinence, and mixed urinary incontinence. Stress urinary incontinence is generally thought to be caused when an increase in abdominal pressure (like a laugh or a sneeze) forces urine out of the bladder. Urgency urinary incontinence occurs when a bladder contraction forces urine outside of the bladder (women with this frequently get strong urges to use the bathroom). Mixed urinary incontinence is when a woman leaks for both of these reasons. While we do not know exactly why extra weight causes urinary leakage, we believe that the extra weight leads to higher abdominal pressures, which can more easily force urine out of the bladder. This extra weight can also lead to more bladder muscle irritability and urgency incontinence. People who carry more weight in the abdomen and have an apple shape or in the hips and legs and have more of a pear shape. The apple shape may be a greater risk for urinary incontinence than a pear shape.

So how much of a difference can extra weight make? The heavier you are, the more risk you have of having or developing urinary leakage. Scientific studies have shown that for every 5unit increase in BMI, the risk of daily urinary incontinence increases by 20-70%. One study of very heavy women (BMI > 40 kg/m2) found that more than 60% of these women leaked urine. This is much higher than what you would find if you studied all women across the general population.

The most important thing to remember is that the impact of weight on urinary leakage seems to be reversible. It is not permanent. Weight loss can lead to less leakage. The first scientific studies done in this area looked at very heavy patients who were undergoing bariatric procedures (like a gastric bypass) to help them lose weight. One such study found that surgically induced weight loss results in improvement or resolution of urinary incontinence in 82% of patients.3

Weight is an important factor when looking at urinary leakage. Losing weight will not cure urinary leakage in everyone but it will help in many women. Weight loss is best achieved with sensible portion control and exercise. This may be very frustrating for some women because they leak more when they exercise and stop exercising. When seeking treatment for urinary leakage, one should expect to have an open conversation about all of the factors that may influence their incontinence. Women should seek advice from their doctor prior to beginning a weight loss plan. And while it is not easy, maintaining an ideal body weight is the healthiest option for all of us.

References:

  1. Subak LL, Richert HE, and Huskaar S. Journal of Urology. 2009; 182(6): 2-7
  2. Subak LL, Wing RR, West DS et al. New England Journal of Medicine. 2009; 360(5): 481-90
  3. Kuruba R, Alamahmeed T, Martinez F, Torrella TA, Haines K, Nelson LG, Gallagher SF, Murr MM. Bariatric surgery improves urinary incontinence in morbidly obese individuals. Journal of the American Society or Metabolic and Bariatric Surgery. 2007; 3(6): 586-590.

About The Author
Dr. Sarah Hamilton is fellowship trained in Female Pelvic Medicine and Reconstructive Surgery and works in Portland, OR. She attended medical school at the University of Pittsburgh, residency at The Ohio State University and fellowship at Oregon Health & Science University. She is a strong believer in individualizing care and helping patients make informed decisions. She performs research in the Providence Health System and her research interests include optimizing outcomes for women.