Definitive Guide to Fats That HURT Fertility: Saturated Fats and Other Fatty Acids

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Now that you’re an expert on why Omega-3 is a really important fat when trying to conceive, you should now there’s on more really important thing to know. There are other types of fat that absolutely wreak havoc on your fertility! Let’s talk about that in this fourth part of my Foods for Fertility series!

Part 1. The Ultimate Fertility Diet: What To Eat When Trying to Conceive
Part 2. Meat, Poultry, Fish, Tofu: Which Protein is Best and Which is Worst for Fertility?
Part 3. Definitive Guide to Fats That HELP Fertility: Omega-3 and Other Fatty Acids
Part 4. Definitive Guide to Fats That HURT Fertility: Saturated Fats and Other Fats
Part 5. Sugar and Other Carbs Suck When Trying to Conceive
Part 6. Artificial Sweeteners When Trying to Conceive or Pregnant: Bad Idea?
Part 7. Two Reasons Coffee is Bad When Trying For a Baby
Part 8. Can I Drink Alcohol When Trying to get Pregnant?
Part 9. Dairy Can Help You Get Pregnant – Everything You Need to Know
Part 10. 10 Fertility Diet Tips to Implement Today

The quick win

Wait! Before you continue reading, consider doing ONE easy thing that is known to boost fertility: taking a daily high-quality prenatal multivitamin. This is without doubt the easiest way to boost your fertility (here’s why). Personally, I love the Smartypants prenatal gummy (because it’s good and tastes yummy) and the Nature Made prenatal vitamin with DHA (because it contains all kinds of goodies that boost fertility and is a trusted brand). (affiliate links)

Fertility Diet: fats and fertility

Before ovulation, your eggs are confined to little fluid filled sacs called follicles. Basically, this is where your egg lives for most of its life and the environment better be comfortable and full of nutrients to help the egg grow!

A group of researchers literally looked at the amount of fat that’s found in the follicular fluid of IVF patients. They found that higher levels of fat in the follicular fluid was associated with lower quality eggs.1 And another study linked an overall high-fat diet to higher levels of oxidative stress in the follicular fluid, suggesting that damage is done to the developing egg.2

Endometriosis is another common condition that can cause problems with conception and it too is linked to higher levels of dietary fat intake!

What we learn from this is that a high fat intake could be seen as a bad thing when it comes to fertility. But is this really true?

I’ll let you in on a little secret: it’s not so much the amount of fat in your diet, but what type of fat you eat. So let’s jump right in and discuss the absolute WORST fat for your fertility.

Trans fats

trans fat cookies

You’ve probably heard of trans fats as a particularly unhealthy fat, but this fact wasn’t always known.

Trans fats occur in small amounts in meats and milk fat, but by and large they are produced (artificially) when vegetable oils are made solid to increase product shelf life. On packaging you can often recognize trans fats by seeing “partially hydrogenated vegetable oil” on the label.

At one point in time not too long ago, trans fats were used as a frying fat, in margarine and shortening, or in off-the shelf products like cookies. And it wasn’t until relatively recently that its use has become much less popular.

Trans fats have been implicated in many aspects of health such as diabetes, stroke and coronary artery disease. In coronary artery disease, arteries surrounding your heart clog up, limiting blood flow to the heart. If it gets bad enough, it could results in a heart attack, which happens when a clot completely blocks the blood flow to the heart.

One huge piece of evidence against trans fats actually came from the Nurses Health Study. Yes, exactly, that same study that uncovered all those fertility and diet relationships. The researchers found that a 2% increase in calories from trans fats instead of carbohydrates nearly doubled the chances of coronary artery disease!3 Clearly, that’s not good.

foods for fertility free ebook

Even though health risks were known since the 1990’s, it wasn’t until 2008 that McDonalds stopped using trans fats for those tasty French fries. In fact, most fast food and non-fast food restaurants, used trans fats up until around that timer. Trans fats weren’t even banned until very recently! Finally, in June 2015, the FDA officially stated that trans fats are labeled is not “generally recognized as safe”.

You might be asking yourself why I’m even talking about trans fats so much if they have now been banned?

Well, as we’ve just learned, some foods might still contain trans fats, and while the United States and Canada and some European countries have finally banned its use or eliminated it from food production, many other countries have not. This includes the U.K. and Australia, as well as most less developed countries. Some countries don’t even require trans fats to be explicitly labeled on the food packaging!

It’s the World Health Organization’s goal to have trans fats banned worldwide by the end of 2023.4,5 So if you see “partially hydrogenated oil” on that yummy looking package of chocolate chip cookies, you should probably let it be!

And when it comes to fertility, trans fats are a BIG deal.

Trans fats and fertility

In the Nurses’ Health Study, researchers also looked at fat intake and ovulatory infertility.6 That is, they posed the question: “do different types of fat negatively influence your fertility due to ovulation issues?” They found that a 2% increase in energy from trans fats at the expense of carbohydrates was associated with a 73% increased risk of self-reported ovulatory infertility.

In other words, trans fats are TERRIBLE for fertility.

Why you may ask? Well, trans fat intake has been associated with increased systemic inflammation and insulin resistance, just as in diabetes, both of which are known to impair ovulatory function.7,8,9

Beyond ovulatory infertility, dietary trans fat intake has also been associated with endometriosis. Endometriosis is a condition where cells that normally line the uterus, instead grow outside of the uterus, for example in the ovaries. It occurs in up to 6-8% of otherwise healthy women and is often painful, but sometimes completely asymptomatic. It is estimated that 30% to 50% of women with endometriosis also have fertility problems.10

If you think you might have endometriosis, talk to your doctor and mention that you’re trying to conceive. There are treatment options that can either alleviate symptoms or improve your chances of getting pregnant. But in the end, many women with endometriosis choose to go down the IVF-path.

Back to the Nurses’ Health Study. The researchers compared the top 20% of trans-fat consuming women to the bottom 20% (women who ate almost no trans-fats) and found that women in the high trans-fat group were 48% more likely to be diagnosed with endometriosis!12 While this is just one study, considering that avoiding trans fat is pretty easy, I’d say you can add “reducing the odds of endometriosis” to the list as yet another reason to avoid trans fats.

The final nail in the coffin for trans fats comes from a study looking at women from all walks of life -not IVF patients- who were trying to get pregnant.13 Researchers followed them for a year and looked at fat intake and ability to conceive.

The results show that trans fat intake was associated very strongly with a lower chance of getting pregnant, while dietary intake of most other fats did not seem to matter much. There was one exception… Omega-3 polyunsaturated fat intake was associated with a HIGHER chance of conceiving… Yes, higher. You can read more about that here.

Saturated Fats

saturated fat steak

A quick note on saturated fats. Even though not much research has been done specifically on saturated fat intake and female fertility, we do know that saturated fat is bad for the male partner.13 Higher intake of saturated fat is associated with lower quality sperm.

Sometimes it’s easy to forget that it’s not all about your eggs and uterus. The other half of the fertility equation is just as important and low quality sperm conceiving is that much harder!

So saturated fats -which are mostly found in meat and animal fats- are bad for sperm cells and we also know that meat, especially red meat, can lower female fertility. It sure sounds like this is a a good time to switch out meat for plant based foods a few nights a week.

The bottom line on bad fats

Alright. You’re ready to hit the ground running. It’s time to remove all trans fats from your diet and to drastically reduce saturated fats. And you’re definitely ready to add Omega-3 to your diet, because, well, Omega-3 is good for your fertility! Especially the long-chain Omega-3’s found in fish (EPA, DHA, DPA).

But because food labels almost never tell you whether something contains Omega-3, trans fat or some other terrible fat, I’ve created a FREE checklist for you to download!

It will tell you exactly which foods you should eat that are really high in the right kind of fat. As a bonus I’ll also tell you which fats and foods to avoid altogether. Doing this is sure to optimize your fertility through diet.

Click here to download the checklist now.


1. Turchini, G. M., Nichols, P. D., Barrow, C. et al. (2012). Crit Rev Food Science Nutrition, 52(9), 795–803.
2. Jungheim, E. S., Macones, G. A., Odem, R. R. et al. (2011). Fertility and Sterility, 95(6), 1970–1974.
3. Hu, F. B., Stampfer, M. J., Manson. et al. (1997). NEJM, 337(21), 1491–1499.
4. World Health Organization. (‎2019)‎. Countdown to 2023: WHO report on global trans-fat elimination.
5. Thornton, J. (2018). BMJ, 361, k2154.
6. Chavarro, J. E., Rich-Edwards, J. W., Rosner, et al. (2007). Am J of Clinical Nutrition, 85(1), 231–237.
7. Mozaffarian, D., Pischon, T., Hankinson, S. E. et al. (2004). Am J of Clinical Nutrition, 79(4), 606–612.
8. Lefevre, M., Lovejoy, J. C., Smith, S. R. et al. (2005). Metabolism: Clin and Exper, 54(12), 1652–1658.
9. Wise, L. A., Wesselink, A. K., Tucker, K. L. et al. (2018). American Journal of Epidemiology, 187(1), 60–74.
10. Bulletti, C., Coccia, M. E., Battistoni, S. et al.(2010). J of Assis Repr and Gen, 27(8), 441–447.
11. Missmer, S. A., Chavarro, J. E., Malspeis, S. et al. (2010). Human Reproduction , 25(6), 1528–1535.
12. Wise, L. A., Wesselink, A. K., Tucker, K. L. et al. (2018). Am J of Epidemiology, 187(1), 60–74.
13. Jensen, T. K., Heitmann, B. L., Jensen, M. B. et al. (2013). Am J of Clinical Nutrition, 97(2), 411–418.

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