Does Fat Equal Infertile?

Being overweight is looked at differently in the modern era. As America’s waist line expands, focus has been redirected to the consequences of those extra pounds. Unfortunately, scores of medical problems have been associated with obesity and its effect of longevity can be profound.

Obesity is commonly associated with several systemic disorders. Obesity is often found in patients with insulin resistance and or diabetes. High blood pressure and elevated cholesterol are also common findings. Furthermore, there is an increased risk of hypogonadism, sometimes as a reflection of poor testicular function in larger men, particularly those with morbid obesity. Any systemic illness can have an influence on a man’s reproductive potential. To make the situation even more concerning, obesity is being recognized as a risk factor for a number of cancers including esophagus, pancreas, colon, kidney and most recently prostate.

Sleep apnea is commonly associated with obesity and may contribute to hypogonadism and infertility. There are a number of possible mechanisms by which this can happen, not the least of which is disruption of the normal sleep wake cycle. In a man, pituitary hormones called gonadotropins which stimulate the testicles are released in a daily cycle. When sleep is disrupted, this cycle changes. Testosterone levels may drop. There are other mechanism at work as well including an increased conversion of testosterone to estradiol.

There are a number of ways to measure obesity. One way is with Body Mass index (BMI)which uses a ratio of weight and height. BMI does have some limitations as it does not adjust for large versus small framed individuals. More recently attention has been turn to waist circumference and waist to hip ratio in an attempt to search for a better metric; however, most literature has persisted in using BMI.

A Study by Belloc et al in the November 2014 issue of Fertility and Sterility reports an association of high BMI and worse semen parameters except for sperm morphology. The study was a retrospective review of semen analysis performed on over 10,000 patients in a single andrology laboratory. In particular, severe obesity defined as a BMI of greater than 40 was associated with a four to five fold increase in the risk of azoospermia (no sperm) or cryptozoospermia (almost no sperm) compared to those with normal BMI in the patient population examined.

Additional evidence from study by Smavat et al in the same journal which reported that the acrosome reaction is impaired in sperm of obese men. The acrosome is an organelle in sperm required for penetration of the egg. Acrosome reaction is a laboratory test which tests this ability, In this study, results from twenty-three obese men where compared with twenty age matched controls. Findings showed almost a double number of abnormal results in the obese population.

When patients see me in the office, BMI is routinely assessed. If appropriate, I have at least a brief discussion about weight loss and or evaluation of sleep apnea. Treatment of obesity may allow better health while simultaneously helping couples to conceive.

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