Decoding The Fertility Diet, Part 1:
Are Carbs Good Or Bad For Fertility?

Written & Edited by: Dr. Will Haas, MD, MBA & Dr. Ashley Eskew MD, MSCI

Last updated: June 8th, 2021

Different answers to whether carbs are healthy when trying to conceive

Ask three different people if carbohydrates are good or bad for your health and chances are you’ll get three different answers.

And unfortunately, the rise of low-carb diets, like Atkins and Paleo, has made the answer to this question even more polarized.

So instead of trying to tackle the question of whether carbs are ‘good’ or ‘bad’ for your health and overall wellness, let’s focus on your fertility for a moment.

The answer to that question is much simpler as it mostly depends on the TYPE of carbohydrates that you consume when following a fertility diet.

What are carbohydrates?

Carbohydrates belong to a category of nutrients referred to as macronutrients, meaning that they are needed in relatively large amounts to provide the body with energy. Notice that we said relatively large amounts… but more on that in a moment.

In short, carbohydrates are the naturally occurring sugars, starches, and fibers found in the food that we eat. All carbohydrates are effectively made up of simple sugars, the most well known being glucose.

When several simple sugar molecules are linked together, they form starches and fiber. Starches are broken back down by our body to form glucose, while fiber passes through our digestive tract relatively intact.

How many carbohydrates should you be eating?

Carbohydrates tend to make up the majority of calories in our diet. In fact, according to the Institute of Medicine, the recommended daily amount of carbs is 130 grams for the typical adult.

Keep in mind this is based on the minimum intake required to supply your brain with glucose and doesn’t account for activity levels or your desire to conceive.

For most individuals, carbohydrate intake should be between 45-65% of your total caloric intake. However, as we’ll explore later in this post, women trying to conceive may benefit from carbohydrate intake closer to 45% of calories.

The truth about 'good' and 'bad' carbs

Even though not all carbohydrates are created equal, technically, there’s no official classification of ‘bad’ or ‘good’ carbs.

What’s typically meant when someone refers to a carbohydrate as being ‘bad’ or ‘good’ is whether it’s a simple or a complex carb.

Generally speaking, most people equate simple carbohydrates as bad and complex as good.
So, let’s take a closer look at simple vs. complex carbohydrates.

What’s the difference between simple vs. complex carbs?

The chemical structure of carbohydrates and how your body digests them is what determines their classification as ‘simple’ or ‘complex’.

Simple carbohydrates are composed of small sugar molecules that are easy for your body to digest. Some of these sugar molecules are naturally occurring, such as those in fruits, while others are highly processed and added into foods like baked goods.

As you can see, simple carbohydrates aren’t necessarily all bad (i.e., fruits), they just get a bad wrap because they raise blood sugar quickly.

With that said, simple, processed carbs are most definitely ‘bad’ as they are associated with insulin resistance, elevated cholesterol levels, and metabolic syndrome – conditions that don’t exactly support your efforts to conceive.

We explore the topic of simple carbohydrates in great detail in our Fertility Foods Formula program, but for now, focus on removing the following simple carbohydrates from your diet to optimize your fertility:

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    Energy drinks

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    Sugar-sweetened sodas

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    Other sweetened beverages (iced tea)

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    Prepackaged processed snacks (chips, pretzels, etc.)

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    Ice Cream

Now, let’s shift our focus to complex carbohydrates.

Complex carbohydrates contain multiple sugar molecules linked together. As a result of this linkage, complex carbs take more time for the body to break down and cause a lower rise in insulin levels.

This slow, steady supply of energy is what makes complex carbohydrates considered ‘good’.
And in their natural forms (yes, we mean vegetables), complex carbohydrates are also packed with vitamins, minerals, and antioxidants to support both your overall health and reproductive health.

As far as real-world examples, complex carbohydrates make up your standard whole grains such as brown rice, quinoa, and oats, as well as legumes like lentils and beans. On the other hand, pancakes are also technically considered complex carbohydrates because of their starch makeup.

Clearly, the classification of carbohydrates into simple versus complex doesn’t tell us the whole picture… because eating a pancake isn’t quite the same as eating lentils… that’s where glycemic index and the glycemic load come into play!

Understanding carbohydrate quality using glycemic index and glycemic load

Glycemic index (GI) measures how quickly a carbohydrate-containing food raises blood sugar. Pure glucose has the highest GI (with a value of 100) and is used as the comparison point for other foods.

Glycemic load (GL), on the other hand, takes into account the amount of carbohydrate that is consumed as well as how quickly that carbohydrate raises blood sugar.

To calculate GL, you multiply a food’s glycemic index by the amount of carbohydrate the food contains per serving and divide by 100; GL = (GI x carbohydrate (amount in grams) / 100).

Glycemic Index & Glycemic Load Key:

glycemic index

GL is more useful when constructing an optimal fertility diet because it tells you the effect a serving of food will have on your blood sugar.

For example, while watermelon is considered to have a high GI (72); however, when you look at the typical serving size of 1 cup, watermelon has a low GL (8). So, as long as you don’t eat the entire watermelon in one sitting, you’re good to enjoy this simple carb.

As you can see, knowing the GL of a food gives you a better idea if that food will cause your blood sugar to spike.

When your blood sugar spikes, your pancreas releases extra insulin to bring it down. Over time, if you continue to consume high GL foods, your body becomes less responsive to insulin resulting in elevated blood glucose and ultimately diabetes. Excess insulin also creates inflammation and hormonal imbalance within the body. Needless-to-say, not a good cycle to get stuck in.

And for our women out there struggling with PCOS, both insulin resistance and inflammation are key factors that make weight loss and getting pregnant so difficult.

So instead of going for the standard high GL snacks (like the sugar-laden “granola bar” or the bag of pretzels laying around the office), try swapping them out for one a low GL counterpart or have a snack rich in protein and fat to hold you over during that afternoon slump.

Why you don’t need to completely cut out carbs

Earlier in the post, we mentioned that carbohydrates make up the largest percentage of our calorie intake. And if you recall, we also said that eating slightly fewer carbs may help your efforts to conceive.

The important concept here is fewer carbs, NOT ultra low-carb or no-carb.

Let’s take a closer look at just how many carbs you should be eating when trying to conceive…

Researchers at Harvard Medical School were some of the earliest to look at carbohydrate consumption and fertility. They found that women who consumed approximately 60% of their calories from carbohydrates (vs. 40%) had a 91% higher risk of ovulatory infertility.

It’s important to point out that there’s minimal evidence at this time to support ultra low-carbohydrate diets or ketogenic-based diets (< 10% of total calories from carbohydrates) when trying to conceive.

Unfortunately, we’ve seen many other blogs tout the benefits of ultra low-carbohydrate intake for fertility based upon a paper published in Nutrients. This paper looked at the outcomes from multiple studies, almost all of which were based on low-carbohydrate diets (~45% of total calories from carbohydrates), NOT ultra-low carbohydrate diets.

We think it’s a bit of a leap to use this one study to make claims about a ketogenic diet for general fertility at this time.

Although low-carb diets or ultra-low carbohydrate diets may make sense for conditions such as polycystic ovary syndrome (PCOS), we have some concerns about these diets when trying to conceive, especially when adhered to for longer periods of time. Learn more about the ketogenic diet and going keto when trying to conceive here.

Our main concern is that it requires the elimination of nutrient-dense foods like fruits, starchy vegetables, and whole grains, which can lead to nutrient deficiencies that impact fertility.

Infographic of The Fertility Diet Plate

As a simple rule of thumb, we suggest that you divide your plate into 3 parts — ½ of your plate should be covered with vegetables and fruit (more veggies than fruit), ¼ with whole grains, and ¼ with protein. Mix in some healthy fats as well.

As for snacks between meals, try mixing carbohydrates with fat or protein if at all possible [e.g., almonds with dehydrated fruit (no sugar added of course) or some almond butter with an apple]. And don’t worry we’ve got great posts on dietary fats and protein intake too.

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Choosing carbohydrates that improve fertility

As you probably guessed, complex carbohydrates with a low GL are the carbohydrates that we suggest eating when trying to conceive, especially if undergoing fertility treatment.

We know you trust us, but let’s take a quick look at what the evidence shows…

The same Harvard researchers that looked at carbohydrate quantity also looked at carbohydrate quality among women trying to conceive. They found that women who consumed the highest amount of high GL carbohydrates had a 92% higher risk of ovulatory infertility compared to those who consumed the lowest amount.

Interestingly, cold breakfast cereals were the worst offender. Increasing intake of cold breakfast cereal by one serving a day elevated the risk of ovulatory infertility by 32%. Just 1 serving! White rice, potatoes (baked, boiled, or mashed), and french fries also increased the risk but not as significantly.

In women undergoing in-vitro fertilization (IVF), the findings regarding carbohydrate quality were even more striking… Women who consumed the highest amount of whole grains in the year leading up to IVF treatment had a nearly 20% higher likelihood of implantation (positive beta-hCG) and live birth compared to those who consumed the least amount.

Final Thoughts

There you have it, the answer to whether carbohydrates are good or bad for your fertility comes down to both quantity and quality.

Eating too many carbohydrates can increase your risk for ovulatory infertility, while eating slightly fewer may help your efforts to conceive. Remember, don’t abandon carbohydrates altogether, just consider modifying your intake slightly.

And as far as quality goes, don’t forget that there’s more to the carbohydrate story than simple or complex. Nutrient-dense, low glycemic load carbohydrates are the best for improving your odds of conceiving either naturally or with assisted reproductive therapies.

Okay, we’ve reached the end of the story on carbohydrates. Check out the next post in the Decoding the Fertility Diet mini-series – Dietary Fats and Fertility.

With Love & Empowerment,
Dr. Ashley Eskew and Dr. Will Haas

P.S. Whenever you’re ready… join other women trying to conceive and reboot your diet for optimal fertility today!

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