If you have done any research on how nutrition affects fertility, you have probably come across a line or two on sugar. Most of us know that sugar really isn’t healthy for us, but few people seem to know the specifics of why sugar is so harmful to hormone balance, fertility, and pregnancy. This article will help you understand the basics of how sugar affects the body, why this is problematic during preconception and pregnancy, and what dietary adjustments you can make to protect yourself from the harmful effects of sugar (hint: it’s not as simple as just quitting candy and ice cream).

Understanding Blood Sugar

The primary reason that sugar consumption is harmful to us has to do with our blood sugar levels. To understand the connection between blood sugar and fertility, we first need to talk about how blood sugar works in the body.

All carbohydrate foods break down into simple sugars in the digestive tract (primarily glucose) which are absorbed into the bloodstream and cause a corresponding increase in our blood sugar levels. How much blood sugar rises depends on the type of carbohydrate we eat and how quickly it is able to be digested down into glucose. There are two major types of carbohydrates: simple and complex. 

Simple carbohydrates 

• Found in sugar, candy, refined flour, fruit juice, etc.

• Have large amounts of glucose molecules arranged in very simple structures

• Break down quickly into individual glucose molecules

• Cause a large and rapid increase in blood sugar levels

Complex carbohydrates

• Found in vegetables, whole grains, legumes, and low-sugar whole fruits

• Have comparatively fewer glucose molecules arranged in more complicated structures

• Contain fiber, which slows the breakdown and absorption of glucose into the bloodstream

• Cause a mild to moderate increase in blood sugar at a much slower pace

When we eat sugar and simple carbohydrate foods, the amount of sugar in our blood rises quickly and significantly. Although we use sugar for energy in our cells, it is actually very damaging to our organs and tissues to have large amounts of free-floating glucose in the bloodstream. To protect us from harm, the body relies on a hormone called insulin to move glucose out of the blood and into our muscle cells for energy production. The more simple carbohydrates we eat, the higher our blood sugar rises, and the more insulin must be released by our pancreas to keep blood sugar levels in a healthy range.

In many people, the amount of insulin released is actually much more than the body needs to bring blood sugar levels back to normal. This can cause sugar levels to quickly drop too low. Low blood sugar is called hypoglycemia and is characterized by energy crashes and cravings for simple carbohydrate foods or stimulants (like caffeine). 

Symptoms of Poor Blood Sugar Regulation

You might recognize the above pattern if you feel hungry or tired an hour after consuming cereal, bread, a bagel, or a candy bar. Those symptoms are a message from your body telling you that your blood sugar has dropped too low and you will naturally crave more quickly-digested carbohydrates to bring it back up. You might even experience more severe symptoms if you go too long without your next sugar fix, such as headaches, shakiness, irritability, or even dizziness. Additional symptoms you can use to evaluate whether you have issues properly controlling your blood sugar levels are:

• Awakening a few hours after falling asleep and having difficulty getting back to sleep

• Relying on coffee or sweets to get through your day

• Excessive appetite or binge eating

• Afternoon sleepiness

• Fatigue that is relieved by eating

• Frequent thirst

• Frequent urination

Developing Insulin Resistance

When we eat simple carbohydrates on a regular basis, the body is forced to pump out insulin almost constantly to keep our blood sugar in normal range. This means that our cells are being bombarded with insulin’s message all day long. Unfortunately, cells do not have unlimited storage capacity for glucose. Once they are completely packed with sugar and cannot receive any more, they begin to reduce their sensitivity to insulin’s message to stop the influx of sugar. This is called insulin resistance. 

When our cells become insulin resistant, we have a harder time regulating our blood sugar and our levels will slowly start to rise. The pancreas will begin working overtime, releasing more and more insulin to try to normalize elevated blood sugar. Eventually, though, it will no longer be able to keep up. This is when we begin to climb the blood sugar ladder toward prediabetes and type 2 diabetes. A recent study from 2015 estimated that 52% of the U.S. adult population is either prediabetic or diabetic and that many of these people remain undiagnosed!

Although most people who go to the doctor regularly will have a good idea of whether they have high blood sugar levels, it is absolutely possible to be insulin resistant without knowing it. This is especially true considering that most doctors do not routinely test insulin levels. However, insulin resistance happens before you ever get an abnormal blood sugar reading at the doctor’s office.

Sugar, Insulin, and Reproductive Health

Here is where things get really interesting – insulin resistance and blood sugar dysregulation are incredibly harmful to fertility, pregnancy, and the health of your future baby! 

Fertility

In women, evidence shows that a high dietary intake of sugar and refined carbohydrates is associated with a significantly increased risk of ovulatory infertility. Insulin resistance in women is also associated with impaired follicle and egg cell development, implantation failure, and poor embryo development. During fertility treatment, higher levels of blood sugar and insulin have been shown to result in lower pregnancy rates. Poor blood sugar regulation may also lead to excess stress hormone (cortisol) production, adrenal dysfunction, depleted sex hormone levels, and reduced thyroid function, all of which can reduce your chances of conceiving.

Insulin resistance is actually a primary feature of polycystic ovary syndrome (PCOS), which is one of the most common causes of female factor infertility. When the ovaries are exposed to high levels of insulin from the bloodstream, they begin to alter their hormone production in favor of male hormones (androgens), which disrupts normal ovulation and can lead to irregular cycles and infertility. You can learn more about PCOS and insulin resistance in this post.

Elevated blood sugar and insulin resistance are also problematic for male fertility. Research shows that higher levels of carbohydrate and sugar in the diet are associated with reductions in sperm concentration and motility. Insulin resistance is also associated with lower testosterone levels and impaired semen parameters. Poorly controlled blood sugar and insulin levels increase inflammation and oxidative stress in the body, which is known to damage both egg and sperm cells and lead to poor reproductive outcomes.

Pregnancy and Childhood Health

Eating refined carbohydrates and sugar during pregnancy is associated with increased risk of preeclampsia, gallbladder problems, excessive weight gain, and having an overly large baby. Insulin resistance is also associated with increased risk of miscarriage and gestational diabetes. Infants born to mothers consuming a high carbohydrate diet are more likely to have a higher body mass index (BMI) during childhood, indicating a lasting effect on metabolism in children. Insulin resistance and higher blood sugar levels during pregnancy have also been shown to increase the risk of neural tube defects and congenital heart disease in infants.

How to Regulate Blood Sugar and Protect Your Fertility

So, what’s the secret? How do we stop blood sugar issues from causing problems with our fertility and the health of our future children? Well, the obvious answer is to stop eating sugar and refined carbohydrates! Candy, ice cream, cookies, and cake certainly come to mind as the first things to eliminate. But really, the focus should be on eating nourishing foods that provide sustained energy and help us avoid constant swings in blood sugar and insulin. 

This means working toward getting all or most of our carbohydrates from the “complex” category discussed at the beginning of the article. It also means making sure we are getting enough fiber, protein, and healthy fats in our diet to slow the absorption of carbohydrates and help regulate our blood sugar and energy levels. Here are some guidelines to get you started.

Eat whole, unprocessed, unrefined carbohydrate foods in their natural form

Aim to get the majority of your carbohydrates from organic, non-starchy, green vegetables and stick to smaller, side-dish portions of organic whole fruit, starchy vegetables, legumes, and whole grains. Eating this way will help reduce the risk of overconsuming carbohydrates and ensure that you get plenty of fiber to help slow the absorption of sugars into the bloodstream.

• Non-starchy vegetables– leafy greens, broccoli, asparagus, cauliflower, bell peppers, celery, cucumber, zucchini, cabbage, etc.

• Whole fruit– low sugar varieties like berries, citrus, green apples, tomatoes, avocados, etc.

• Starchy vegetables– potatoes, sweet potatoes, taro, parsnips, etc.

• Legumes– chickpeas, lentils, black beans, peas, green beans, etc.

• Whole grains (not whole grain flour)– amaranth, buckwheat, quinoa, rice, millet, etc.

Consume balanced meals that include quality protein and healthy fats

In addition to the above complex carbohydrate guidelines, you should also make sure to include at least some protein and healthy fat with each meal. Similar to fiber, protein and fat will slow the breakdown of carbohydrates and help keep blood sugar stabilized throughout the day. 

Good protein sources include organic pasture-raised animal products, eggs, wild-caught fish, nuts and seeds. Legumes and whole grains also contain some protein, but keep in mind that these foods are rich sources of carbohydrate and should be consumed in smaller amounts for those with blood sugar issues. 

Healthy fats include butter, olive oil, coconut oil, avocados, nuts, seeds, and fat from pasture-raised animals. Avoid consuming processed vegetable oils (canola, corn, soybean, cottonseed, safflower, etc.) or trans fats from hydrogenated oils. Trans fat consumption can cause or worsen insulin resistance and lead to a variety of other health issues.

Avoid processed, refined carbohydrates

It can be difficult to give up foods high in sugar and refined carbohydrates, especially if you have lived your entire life eating these foods regularly, are inexperienced with preparing your own food from scratch, or depend on packaged convenience foods to get you through your busy work days. However, this is an important step toward optimizing fertility in both partners and can help contribute to better health outcomes for you and your future baby. Do your very best to avoid:

• Anything made from flour – bread, pasta, crackers, pastries, cookies, cereals, etc.

• All forms of added sugar – including natural sugars like honey, maple syrup, and agave

• Soda, sweetened beverages, energy drinks, and fruit juices

• Artificial sugars and sweeteners 

Generally, if it comes in a bag or a box, it’s not the best choice. However, if you are going to eat something you did not prepare yourself, then start reading labels. Sugar hides under more than 50 different names on processed food labels, so it is important to know what to look for. You can learn to identify the many forms of sugar here.