Infertility and weight issues – understanding the link

Infertility can be caused by a range of factors – from general health issues to cancer treatment – and a growing body of scientific knowledge is now also confirming the link between infertility and excess weight and obesity.

In this article, we share some of the implications of weight problems and obesity for fertility as highlighted by recent studies and provide expert advice for managing weight and reducing obesity, which will significantly improve the chances of falling pregnant.

Our fertility specialists at Cape Fertility have always recommended that couples struggling with infertility should immediately prioritise a healthy body weight and healthy lifestyle choices. Now more and more scientific studies are confirming a link between infertility and weight problems and obesity.

Of course, being overweight or having obesity does not invariably mean that you will have fertility problems. Many overweight and obese people conceive without problems. However, in many couples, it is a contributing factor in one or both partners and, according to the American Society for Reproductive Medicine (ASRM), obesity is the cause of fertility struggles in about 6% of women who have never been pregnant before.

How does obesity affect fertility?

In a recent Health Central article How Obesity Affects Your Fertility several studies and research results are discussed that have shown that weight problems and obesity are linked to infertility.

For example, data shows a correlation between a higher body mass index (BMI) and a lower success rate for a healthy pregnancy. Firstly, obese women will more likely have irregular menstrual cycles, which will negatively impact their ability to fall pregnant. Some experts think that obesity impacts fertility by affecting the body’s sex hormones, which in turn impacts the complex metabolism that regulates ovarian function.

Obesity is also linked to lower success rates when undergoing assisted reproductive technology (ART) treatments, such as hormone-stimulating medications and IVF (in vitro fertilisation). In fact, specialists may recommend postponing ART treatments until a patient has achieved a healthier weight.

Some studies suggest that women that have obesity are also more prone to miscarriages, early pregnancy loss and a variety of pregnancy health problems such as gestational diabetes, gestational hypertension, preeclampsia and obstructive sleep apnea.

When it comes to men, obesity can also affect men’s fertility levels through sexual dysfunction, reduced semen quality, lower testosterone levels, impaired functioning of the testes and sperm problems caused by high body temperatures around the scrotum, a common occurrence in obesity.

Obesity may also be linked with other chronic conditions, such as diabetes, that may have an adverse effect on fertility.

Managing weight for fertility

For all these reasons, couples who want to start a family should prioritise a healthy BMI for both partners, as well as healthy lifestyle choices, such as not smoking or drinking, getting enough exercise and avoiding toxic exposures.

Weight loss by itself can improve the chance of unassisted conception. Some research has found that losing even just 5% to 10% of body weight can increase the chance of becoming pregnant in women who have obesity. Weight loss is also extremely helpful in terms of improving cholesterol, insulin levels and blood pressure, which will also increase the chance of conception, and can even restore ovulation.

In addition, a healthy weight will boost the chances of success of fertility treatments that are received, and losing weight before falling pregnant will also decrease the risks of pregnancy complications. Going into a pregnancy in good health – with a normal BMI, and insulin levels, cholesterol and blood pressure all well controlled – improves the chances of a healthy pregnancy and a healthy baby.

How to manage your weight

One way to know where you are now in terms of a healthy weight is the body mass index or BMI. The formula is BMI = kg/m2 where kg is your weight in kilograms and m2 is your height in metres squared.

Knowing your BMI provides a starting point from which to improve over the long term. A BMI between 19 and 25 is considered normal. A BMI above 25 is considered overweight while a BMI over 30 is considered obese, and above 35 – morbidly obese.

At Cape Fertility, we usually aim for an initial target of losing 10% of your body weight and to reach a healthy BMI. So, if for example you weigh 100kgs, you might start off with an initial target of losing 10% of your body weight, or 10kgs.

Because weight loss is mostly achieved through eating correctly, you might want to consult a dietician but we at Cape Fertility are also able to recommend a referral to a dietician if deemed necessary. It is also important to find a form of exercise that you enjoy.

At Cape Fertility, we follow the recommendations provided by the European Society of Human Reproduction and Embryology or ESHRE.

ESHRE recommends decreasing your calorie intake by about 30%. Some of our patients use one of the many apps online to assist them in keeping track of what they are eating and understanding their intake of daily calories, so they can make improvements.

We can also use medical treatments to assist with weight loss, but this depends on the patient profile.

When it comes to exercising, one commonly cited goal is 10,000 steps a day. ESHRE recommends 250 minutes of moderate intensity exercise a week, which is about 50 minutes of moderate intensity exercise, five times a week. If you do more vigorous exercise, such as running or high intensity interval training, five sessions of 30 minutes each per week is recommended.

The best diet to follow

With regard to managing weight and reducing obesity, which is known to reduce the chances of pregnancy, Cape Fertility gladly shares the advice below from the European Fertility Society in their Fertility Patients Care Guidance. (You can download the pocket version of the Guide from

– Instead of a low-fat diet, rather limit carbohydrate intake (potatoes, pasta, rice, beans) to no more than a small portion at each meal.

– Include healthy fats, protein and fibre in each meal to keep hunger pangs at bay – consider for example eggs, poultry, fish, nuts and seeds as well as all vegetables.

– Foods to include in a healthy eating plan include legumes, wholegrains, fruits, vegetables, olive oil, poultry, eggs, fish – including oily fish twice a week, as well as herbs and spices.

– Foods that should be limited include red meat, sweets, and products made from refined flour such as white bread and pasta.

– Snack on high calorie, nutritious foods such as nuts, seeds and avocado on crackers.

– Cook from scratch wherever possible and avoid heavily processed foods.

– Underweight partners should not eat ‘junk foods’ in order to gain weight. Instead, it should be explored whether their digestive systems require attention and screening for coeliac disease is important, as this may affect nutrient absorption without exhibiting any gastrointestinal symptoms and also seek the help of a dietician to assist with weight gain in a healthy manner.

– The Mediterranean diet is mostly akin to the types of foods that promote fertility. Use the Mediterranean diet pyramid or a good Mediterranean cookbook.
With timelines in mind, any length of time is beneficial, but three to six months is an ideal timeframe to focus on nutrition and lifestyle changes to enhance fertility health.

Reach out for help!

There is a definite link between a healthy weight and fertility, and maintaining a positive BMI is a first step every couple can take immediately. However, there are also many other causes of infertility in both men and women, and often there are multiple contributing causes when a couple experiences infertility.

If you are concerned about your fertility, we invite you to reach out to us – simply contact us by clicking here…
At Cape Fertility, we value each individual patient and we look forward to providing you with individualised and personalised care, affordable quality fertility treatment, and higher success rates at our purpose-built premises in the beautiful city of Cape Town.

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