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The Link Between Body Fat, Estrogen and Impaired Fertility

The Link Between Body Fat, Estrogen and Impaired Fertility


Estradiol (compound) by PubChem

Whether you are a man or a woman, you have estrogen in your body, even though estrogen is considered a “female hormone”. The amount of estrogen in a woman’s body varies with her age and menstrual cycle. Premenopausal women make estrogen in varying amounts from the ovaries, which partially dictates her ability to ovulate, the thickness of the uterine lining, and the health of the egg.

Estrogen in Women vs. Men

Women, estrogen in your body:

There are three kinds of estrogen a woman can have. In premenopausal women, the dominant estrogen is estradiol or E2. This is also the estrogen type seen in estrogen dominance.

Postmenopausal women make more estrone or E3. In pregnancy, the levels of estriol or E1 increase, although it is not considered a dominant estrogen in any situation.

Postmenopausal women make much less estrogen and it doesn’t come from the ovaries. In these women, estrogen is primarily made by body fat. Adrenal gland hormones are converted to estrogen. The amount of estrogen in the body depends on how much is made and how well it is cleared from or “metabolized” by the body.

Men and estrogen:

Men, of course, do not have ovaries but they still make estrogen. An enzyme commonly found in body fat called aromatase will convert the testosterone in the body to estradiol. Why is this important? Research on men has shown that estrogen imbalances, namely estrogen dominance, is a cause of benign prostatic hypertrophy (enlarged prostate), atherosclerosis, coronary artery disease, and stroke. Low estradiol levels, on the other hand, contribute to osteoporosis and fractures.

As you can imagine, it’s all about estradiol or “estrogen” balance. This is true for both men and women. In men, the estrogen levels can be tested. If the level is too low, aromatase levels are not sufficient and they need to be increased. In many men, though, aromatase levels are too high and there is too much estrogen. It turns out that chrysin, which is a plant flavonoid, or lignans from spruce trees can suppress the aromatase activity so that estrogen levels will decrease.

Body Fat and Estrogen

A 2008 study from the journal Human Reproduction sheds some light on the effects of body fat on estradiol levels. The results are very interesting. It turns out that there isn’t a linear relationship between estrogen levels and body fat. Researchers checked the estradiol levels throughout the menstrual cycle on more than 140 women.

Study findings:

Women who had a low body fat percentage (less than 22 percent body fat) had low estradiol levels. This makes sense because they don’t have the body fat aromatase levels to make estrogen. What’s surprising is that women with very high body fat levels also had low estrogen levels. These women instead had high androgen (male hormone levels) and decreased fertility.

They also found a fascinating correlation between energy balance and estrogen levels. Women with a positive energy balance are those who are putting away more calories than they are using. They are eating too much and they aren’t exercising. On the other hand, women with a negative energy balance are using more energy than they are taking in. They are exercising and eating sensibly.

Those with a positive energy balance had a strong relationship between estrogen levels and their body fat percentage while those with a negative balance had no relationship between body fat and estrogen levels. What does this mean? It means that exercise is important to your estrogen levels and estrogen dominance. This is true whether you are overweight or underweight.

The important of healthy body fat levels for women…

Women with low body fat percentages (because they have low estrogen levels) have a lower chance of getting pregnant than normal body fat women. In the same way, women with a high body fat percentage also do not get pregnant as easily, probably from high androgen levels and low estrogen levels. There are things you can do to improve your pregnancy chances:

  • Check your body mass index (BMI) and make sure it’s between 21 and 25 for optimal fertility.
  • Eat a healthy diet.
  • Exercise daily so your energy levels are balanced, which will help balance your estrogen levels.

The Problem of Estrogen Dominance

While it’s all about balance, having too much estrogen or “estrogen dominance” is far more dangerous than having too little estrogen. Estrogen dominance is a huge problem in industrialized countries. In women, it can cause breast cancer, polycystic ovarian syndrome (PCOS), endometriosis, premenstrual syndrome, uterine fibroids, and cystic breast disease.

Women with estrogen dominance can have a host of symptoms, including the following:

  • Low sex drive
  • Abdominal pain
  • Thyroid problems
  • Premenstrual syndrome
  • Abnormal periods or heavy periods
  • Low metabolic rate (poor metabolism)
  • Insomnia, fatigue, and brain fog
  • Increased belly fat and hip fat
  • Fibrocystic breasts

Men who have estrogen dominance will notice having a pear-shaped body and bigger hips, increased emotional reactivity, low testosterone (because it’s all going to make estrogen), and gynecomastia (enlarged breasts).

Estrogen levels depend on the rate it is made PLUS the rate it is cleared from the body by the liver. If, for some reason, the liver is sluggish, estrogen will build up. In fact, when losing weight estrogen dominance may temporarily increase as estrogen is released from body fat and not metabolized well from the liver.

So, what contributes to estrogen dominance?

There are so many reasons this can happen. If you are obese, you are making estrogen through the aromatase in body fat and there will be too much estrogen. Lack of exercise and poor digestion will contribute to the problem. Birth control pills and estrogen replacement drugs contain estrogen. Stress will decrease estrogen clearance. There are estrogens in the environment that will act like the estrogen in your body, leading to estrogen dominance.

In women, higher levels of progesterone will counteract estrogen dominance. If you’re under a lot of stress, your stress hormone, cortisol, will increase and will overwhelm the liver so estrogen can’t be cleared. There is also a phenomenon called the “pregnenolone steal” in which the precursor to progesterone instead goes to making cortisol and you won’t have enough progesterone to counteract estrogen dominance.

The Problem of Environmental Estrogens

There are so many environmental estrogens and chemicals that will mimic estrogen, contributing to estrogen dominance. If you are worried about estrogen dominance or have this problem, there are things in the environment that you will want to avoid exposure to in order to balance your hormone levels and reduce estrogen dominance. These include the following environmental sources of estrogen:

  • Nail polish and acetone used to remove nail polish
  • Plastics (think of water bottles, plastic storage containers, and sodas in plastic bottles)
  • Perfumes, which are petrochemicals
  • Surfactants—often found in contraceptive gels and condoms
  • Fabric softeners, which contain petrochemicals
  • Pesticides, fungicides, and herbicides—found on unwashed vegetables you buy at the store
  • Noxious fumes from flooring, new carpeting, and copy machines

What about the Liver?

Clearance of estrogen is crucial and only your liver can do that. There are two pathways in the liver (called Phase I and Phase II) that can turn fat-soluble estrogen into water-soluble estrogen. Once the estrogen becomes water soluble, it can be eliminated from your body through the feces (your bile), urine and sweat.

There are numerous things you can take for liver support so that it can do its job detoxifying estrogen.

First, learn more about Why Liver Health is Important to Your Fertility. Then learn more about fertility cleansing, DIM, Maca and Royal Jelly.

If you have estrogen dominance, you could also work with a qualified herbal healthcare practitioner who can advise you on which supplements to take for liver support. There is both an art and a science to correctly doing this so you’ll want to have help with what to take and how much to take.

Foods for Estrogen Dominance

If you think you are estrogen dominant, there are foods to eat and foods to avoid.

These are the foods you SHOULD eat:

  • Flaxseeds—these will help with estrogen elimination
  • Organic meats and dairy products
  • Cruciferous vegetables—these will lower estrogen levels
  • High fiber vegetables—think artichoke hearts and beets, which will help in estrogen elimination
  • Bean sprouts—these will prevent absorption of estrogen in the GI tract
  • Broccoli sprouts—these are the seedlings of broccoli, which are high in sulforaphane, which lowers your estrogen levels much better than mature broccoli

This is what you want to AVOID eating:

  • Too much coffee (it can increase your estrogen level)
  • Soy products (this is controversial but you should probably avoid these if they aren’t fermented) – avoid tofu in particular
  • Processed meats or luncheon meats (you will retain water and these contain estrogen)
  • Pasta and things made with white flour (these will be low in fiber so you won’t clear estrogen as well)
  • Harmful fats (think hydrogenated fats, cotton seed oil, palm oil, vegetable oils, and trans fats found in highly processed foods)
  • Alcohol (this will increase your estrogen level and increase your risk for breast cancer)

The take home message

The level of estrogen in your body depends on how much is being made and how well it is cleared. You need to have a normal body weight for estrogen balance and you need to exercise. If you have estrogen dominance, you also need to reduce your exposure to estrogen in the environment and you need to support your liver, which is the main organ for estrogen clearance in your body.


Hethir Rodriguez - Certified Herbalist, Nutritionist, Birth Doula
Hethir Rodriguez - Certified Herbalist, Nutritionist, Birth Doula

Hethir Rodriguez is the Founder and President of Natural Fertility She has been a Certified Herbalist for over 19 years, holds a Bachelors degree (BS) in Nutrition Sciences and is a Certified Birth Doula.  Since founding Natural Fertility in 2007, Hethir has written and co-authored over 1200+ articles on Fertility; and her research, articles, and guides have been read by over 40,000,000 people.  Hethir has dedicated her life to helping provide a source for high quality, research based information and support for those on their journey to becoming parents.

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