The link between infertility in women and obesity

Old wives’ tales abound regarding the relationship between obesity and infertility, however, the link to obesity at least in females has been established quite some time ago. A study in 1979 examined historical data and medical records of 26,638 women between the ages of 20 and 40 to establish that obesity has a direct association and effect on menstrual abnormalities, including evidence of infertility. (1) In the same study, conducted by researchers for the International Journal of Obesity, it was shown that women with “irregular cycles (…) that lasted longer than 36 days were found to be more than 30 lb. heavier than women with no menstrual abnormalities.” (2) Some of the abnormalities found in obese women were irregular cycles, virile hair growth with facial hair and heavy flow. In fact, a “longer duration of obesity was associated with facial hair,” (3) clearly indicating that obesity has some great effect on hormonal imbalances in the female body.

While the link between obesity and infertility in women is thought to be because of the way insulin (created in the pancreas to normalize blood-sugar levels) reacts with hormones, recent research has shed light on a deeper mechanism than that. Previously, fertility problems in women were linked to a resistance to the hormone insulin. (4) The actual mechanism is a lot more complicated. Obesity is caused by a diet rich in carbohydrates and a lack of exercise. At least this was the case in grain-fattened mice used in the study that this research underpins. (5) Carbohydrates are converted into glucose during digestion and this causes blood-sugar levels to spike. Insulin is normally released into the bloodstream to control the sugar, but if there is always an abundance of glucose in the bloodstream then the insulin has to work extremely hard and is released in greater quantities by the pancreas. Eventually, the body becomes desensitized to the effects of insulin and this is also what causes type 2 diabetes. In the mice used in the study, the insulin also signaled the release of an overabundance of fertility hormones from the pituitary gland and in a similar desensitizing mechanism, led to the infertility issues in the mice. (6) Science Daily calls this effect a “heightened sensitivity to insulin’s effects on the pituitary gland.” (7)

The tie to metabolism established

These studies highlight that the body’s metabolism and fertility are intricately linked, at least in the female body. This supports the idea that a healthy and balanced diet, restricted in the intake of sugar-producing foods, can lead to a balanced natural fertility cycle. The adage, “you are what you eat” takes on a whole new meaning in this light. This study and similar research in the future can lead to treatment of type 2 diabetes, metabolic syndrome as well as polycystic ovary syndrome, (8) which effects up to one in 10 women. Backing up this information, a Ft. Lauderdale infertility clinic says that they have a “fair amount of patients who are 100 to 150 pounds overweight.” (9) In addition to this, Dr. Ellen Wood, a reproductive endocrinologist working at the South Florida Institute for Reproductive Medicine says that 10-15% of the patients have some sort of weight-related infertility and that they routinely advise their patients to seriously consider weight-loss as a first step to solving these problems.

Obesity and infertility in men

The link between obesity in men and men’s infertility is not so well established, however. A study published in the September 2006 issue of Epidemiology could find a correlation between infertility in men and their obesity levels, however, further studies need to be completed to figure out exactly the mechanism involved, if any. (10) What was discovered though, is that “men with increased body mass index were significantly more likely to be infertile than normal-weight men.” (11) This data was gleaned after factors for the high BMI of the woman, age, cigarette smoking, alcohol intake, and solvent and pesticide exposure were eliminated. (12) The only data the researchers did not have which calls for further study of the exact mechanisms involved is the frequency of sexual intercourse between the farmers researched and their wives. (13) The study does also highlight that reduced semen quality and hormonal imbalances could also be linked to infertility in obese men. (14)

Another study, conducted a year later and published in Endocrinology, Diabetes & Obesity, states that in men, “obesity is associated with low testosterone levels.” (15) The research goes on to say that in “massively obese individuals, reduced spermatogenesis associated with severe hypotestosteronemia may favour infertility.” (16) Erectile dysfunction was also linked to increasing body mass index in the same study. (17) In a similar study, it was shown that body mass index and skinfold thickness are both negatively correlated with testosterone. In other words, the higher the BMI and the thicker the layers of body-fat under the skin, the lower the testosterone levels are. (18) The evidence is clear in this respect – obesity is definitely an infertility factor in otherwise normal men. A further study published in the same journal went on to define that obesity, probably through interaction with hormones, can change sperm parameters and cause erectile dysfunction. (19) Sperm was shown to be both less densely concentrated and less motile. (20)

How to solve infertility caused by obesity

In general, obesity has been shown to have a significant effect on fertility issues in both men and women. This has been shown to happen on a biochemical level, but since hormones and physical appearance also have an effect on psychology there could also be other factors at play that work in tandem with the effects of obesity on the body on the chemical level. The solution, as with all obesity-related disorders, diseases and illnesses, is to lose weight by altering your diet and introducing regular physical exercise to your routine.