More Fat, Less Eggs; How Does Obesity Affect Your Fertility?
According to WHO, obesity is defined as “abnormal or excessive fat accumulation that presents a risk to health”. The most convenient and accepted method of measuring the degree of obesity is through the use of body mass index (BMI) formula, calculated as weight in kilograms divided by the square of height in meters (weight(kg)/height2(m2)). A BMI of less than 18.5 is considered low, while 18.5-24.9 is normal, and 25-29.9 is overweight. Once the BMI reaches 30 and above, then it is consistent with obesity which has its own classification: Class 1 (30-34.9), Class 2 (35-39.9) and Class 3 or Morbid Obesity (40 and above).
In this Blog, we will discuss how our body fat content influences our culture, traditions, health in general, and finally and most importantly, a woman’s reproductive health.
Body fat content, aside from being related to one’s health, has influenced our culture and traditions, most likely since the dawn of humanity. It has been a pendulum over the centuries, being regarded as healthy during some periods of time, and unhealthy during others. The woman of Willendorf in Austria from circa 25-30,000BC, seated woman of Catalhoyuk, Turkey from circa 6,000BC, are statuettes that depict obese women with ample abdominal fat content and are thought to represent health, wellness, affluence in the society and were even considered as fertility symbols. However, around couple of centuries BC, Egyptians were “vomiting and purging themselves thrice a month to preserve their health” (Herodotus ∼ 440 BC. Euterpe, section 77), while, at around the same time period, the Greeks realized that ‘…it is very injurious to health to take in more food than the constitution will bear, when, at the same time one uses no exercise to carry off this excess” (Hippocrates ∼ 400 BC De Flatibus). However, the pendulum swung again during Renaissance, as depicted in the paintings of Rubens and Renoir, where obesity was almost synonymous to beauty, so much so that the term “Rubenesque” was coined to describe corpulent women. However, around 18th-20th Century, for the first time after Egyptians’ and Greeks’ description, the health hazards of obesity started to become obvious. In 18th Century, William Cullen, a Scottish Physician, associated obesity with fatigue, gout, and breathing difficulties. In the following century, Louis Dublin from Metropolitan Life Insurance Company, associated excess weight with increased mortality. However, despite the realization of adverse health consequences of obesity over the last Century, obesity turned into an epidemic, not only in United States, but in the whole world, most likely due to easy and improved access to unhealthy high calorie food and establishment of a more sedentary lifestyle. Today, according to CDC, two thirds of the US population is overweight or obese.
Obesity is a chronic inflammatory disease. It affects our health in many ways: Obese women are more likely to have high blood pressure, diabetes, heart diseases, metabolic syndrome, gout, gall bladder disease, obstructive sleep apnea and osteoarthritis. Similarly, obese pregnant women are at increased risk for high blood pressure and diabetes during pregnancy, cesarean delivery, wound infection and overly large babies. Risk for cancer of the lining of the uterus and ovary increases with increasing body fat content, and finally, obese women are at higher risk for urinary incontinence when compared to lean women.
Elevated body fat content affects reproductive function as well. For example, increased fat content in the body leads to elevated estrogens (female hormones) that interfere with normal pulsatile release of hormones from the brain, that lead to infrequent or sometimes complete lack of ovulation. This is one of the main reasons of infertility among obese women. However, even obese women who have regular periods and ovulate regularly take longer time to conceive when compared to lean women. Even among women who undergo in vitro fertilization to conceive, where ovulation is not a factor, the likelihood of conception decreases with increasing body fat. These findings suggest that the obesity may affect the quality of the egg that is ovulated or interfere with the implantation of the embryo due to effects on the lining of the uterus.
As we mentioned before, obesity is a state of chronic inflammation, and we and others have demonstrated that markers of chronic inflammation are elevated in the serum and follicular fluid (the fluid in which the egg grows and matures) of obese women. These inflammatory molecules may attract inflammatory cells that may damage the organs (like ovaries and hence the eggs) and reduce the fertility potential of a woman. However, obviously, not every obese woman is infertile. Hence, the type of the food that one eats may determine the effects of obesity one’s body. For example, high fat diets lead to a chronic low grade inflammation at a systemic level, affecting all organs in the body. Not all types of fat have the same affect though. Saturated fatty acids seem to have the most detrimental changes in terms of causing chronic inflammation while omega 3 polyunsaturated fatty acids have beneficial anti-inflammatory properties. Another example to this type of harmful food is the ones that contain high amount of the so-called “advanced glycation end products”. These are formed by excess heating of the food and they are abundant in Western diet. They may stimulate a cascade of inflammation in the body and lead to adverse reproductive outcomes.
Here at RMA of New York, you can get more information regarding healthy food ingestion from our physicians and registered dietician, Dara Godfrey. The main point to keep in mind seems to be the fact that appropriate caloric intake and a healthy diet are the main determinants of a healthy life and reproductive function in terms of food that we ingest.