Nutrition and Fertility

Most people know that being overweight raises the risk of almost every major health problem, including cardiovascular disease, diabetes and some cancers. What hasn’t gotten as much attention is the fact that both obesity and being overweight can affect fertility as well.

Research has shown that a disproportionate number of women (about 40%) who seek infertility treatment are overweight or obese. A study involving more than 5,000 infertile women who were treated at an infertility clinic in Australia found that 23% of the subjects were considered overweight and 17%, obese.

Research also ties obesity to poorer outcomes in women who undergo in vitro fertilization (IVF). For example, another study tracked some 8,500 women who underwent IVF in the Netherlands and found that those who were overweight or obese had a significantly lower success rate of having a live birth as compared to normal-weight women.

What’s the Link?

One common finding in obese women with fertility problems is a tendency towards abdominal obesity, or an “apple-shaped” body. Exactly how excess body fat affects fertility is not completely understood, but obesity is known to influence reproductive function in several ways:

“¢ Obese women are more likely to menstruate irregularly or not at all. This is due to the presence of excess subcutaneous fat that produces large amounts of the estrogen hormone.

“¢ Obese women are more likely to have problems with successful ovulation and a poorer response to fertility drugs.

“¢ Obese women are at increased risk for miscarriage, both spontaneously and after infertility treatment.

“¢ Obese women are also at higher risk of pregnancy-related complications such as gestational diabetes, hypertension and preeclampsia or toxemia, which poses a threat to both the mother and developing fetus.

“¢ In addition, many obese infertile women suffer from a hormonal disorder called polycystic ovary syndrome (PCOS).

PCOS is a major cause of infertility and is thought to affect 5% to 10% of women of reproductive age. Many researchers believe that the underlying problem in PCOS is that although insulin levels are normal, there is insulin resistance, a primary cause of type 2 diabetes. This is worsened by excess weight. It impacts fertility because the insulin resistance causes elevated circulating insulin levels that result in hormonal imbalances in the ovaries. These hormonal imbalances can then interrupt the normal cycle of ovulation and make it difficult to conceive.

Maintaining normal reproductive function requires a complex balance of sex hormones. Being overweight can upset this balance “” with or without PCOS “” and contribute to infertility in several ways:

“¢ Excess abdominal fat can increase production of androgens, which are male sex hormones that are normally present in small amounts in normal women. Their levels need to stay consistent for normal ovulation to occur. If androgen levels soar, ovulation may be disrupted and conception cannot occur

“¢ Excess body fat can trigger imbalances of the hypothalamus and pituitary hormones in the brain that are needed for normal ovulation.

“¢ Even without a full diagnosis of PCOS, an obese woman can still have insulin resistance that leads to increased levels of circulating insulin. With more insulin in circulation, the balance of sex hormones in the ovaries can be disrupted, interfering with the delicate reproductive hormonal balance needed to trigger ovulation and contributing to infertility.

Not Just a Female Problem

According to a recent study from the National Institute of Environmental Health Sciences (NIEHS) that involved more than 5,500 couples, men who are overweight or obese are also more likely to experience infertility than normal-weight men regardless of their age. The results were published in the September 2006 issue of Epidemiology.

Rate Your Weight

In the past, doctors used weight charts to help determine whether a person was within a healthy weight range.Now they use a new method called body mass index, or BMI.

BMI is calculated using your weight and height and can help doctors determine whether someone might be carrying enough excess fat to be considered a health risk

For adults older than 20, BMI results are interpreted using standardized categories that are the same for both men and women:

BMI Weight Status

Below 18.5 Underweight

18.5 – 24.9 Normal

25.0 – 29.9 Overweight

30.0 and above Obese

While BMI is considered a good assessment tool for most people, some healthy individuals (for example, professional athletes) may rate as overweight because they have excess muscle contributing to their weight.

If your BMI puts you in the overweight or obese category and you’re having difficulty conceiving, you may want to talk to your doctor about whether excess weight could be a factor.

Eat Well; Lose Weight

The good news is that even modest amounts of weight loss can have a positive effect on fertility. Weight loss of as little as 10% to 15% will enhance a woman’s chances of conceiving by normalizing sex hormone levels.

“¢ Here are some simple steps you can take to get your own weight loss rolling in the right direction:

“¢ Move, move, move. Both long periods of exercise and short bouts of activity accumulated over the day are effective for weight loss.

“¢ Spread out your food intake. Extreme hunger can lead to rapid overeating that leaves you feeling “stuffed.” Eating smaller meals throughout the day can help you avoid big pangs of starvation “” and the associated binging.

“¢ Aim for 5 or more servings of fruits and vegetables every day. They’ll help you feel full without loading you down with calories. Add a fruit to breakfast, munch on raw vegetables and fruits as snacks and include salads or cooked veggies with other meals.

“¢ Watch your portions. Aim for a “healthy plate” that’s about half noncarbohydrate types of vegetables and fresh fruits, with the remaining half split between lean proteins (lean meat, skinless poultry, seafood, tofu or beans) and whole grains (brown rice, whole wheat pasta or whole-grain bread).

“¢ Be selective about what you’re eating. Don’t just eat something because it’s there “” make conscious food choices. If you shift into “eating overdrive” under pressure, talk to an expert about stress management strategies that don’t involve food.

“¢ Hire help. Registered dietitians are trained professionals who can help you develop a personalized approach to weight loss. Locate one online through the American Dietetic Association at You can also find nutritionists and weight-loss support groups at local hospitals and community health centers.

Stay Positive

The thought of trying to lose weight while enduring the stress of infertility may seem overwhelming, but don’t lose hope. Even small lifestyle changes that result in modest weight loss may be enough to help you conceive “” and experience a healthier pregnancy.

Seek the Help of a Professional

Scheduling an appointment with a nutritionist is one of the first steps to take control of this disorder and help reduce your symptoms.