The connection between diet and fertility has garnered increasing attention in recent years. Among the various dietary approaches, low-carbohydrate diets have emerged as a topic of interest for individuals seeking to enhance their fertility, particularly those who are overweight or have specific conditions like polycystic ovary syndrome (PCOS). This article explores the potential effects of low-carb diets on fertility, drawing upon research findings and expert opinions.
Understanding Low-Carb Diets
Low-carbohydrate diets (LCDs) involve reducing carbohydrate intake while increasing protein and fat consumption. There are many variations of LCDs and they differ by how much restriction they place on total carbohydrate intake. The American Academy of Family Physicians defines LCDs as having less than 20% of calories coming from carbohydrates. Carbohydrates are a type of macronutrient, like proteins and fats and come in the form of fiber, starches and sugars. When food that contains carbs is eaten, the carbs are broken down into glucose (aka sugar) and that glucose enters the blood (blood sugar). When our body senses a rise in blood sugar, insulin is released from the pancreas to help that glucose enter the body’s cells to be used for energy or stored for later use.
The Appeal of Low-Carb Diets for Fertility Enhancement
The ketogenic diet is all the rage these days among those who are looking to shed a substantial amount of weight quickly. Given that being overweight or obese can reduce your chances of getting pregnant or staying pregnant (having excess body fat is associated with a higher risk of miscarriage), overweight women who want to have a baby may be wondering if the keto diet could help them slim down and boost their fertility at the same time. A ketogenic diet puts your body into a natural metabolic state called ketosis. By dramatically reducing your intake of carbohydrates (its primary source of energy), your body is forced to become super efficient at burning fat for energy instead. Preliminary research suggests this shift can enhance weight loss temporarily, as well as help reduce systemic inflammation, which is important because “inflammation can reduce overall fertility,” says Kristin Kirkpatrick, RDN, a wellness nutrition services consultant at the Cleveland Clinic Wellness Institute in Ohio.
Low-Carb Diets and PCOS
“Using a ketogenic diet to improve body weight can definitely help women who do not ovulate - release an egg - regularly, including those with polycystic ovary syndrome,” explains Rashmi Kudesia, MD, a reproductive endocrinologist and infertility specialist at CCRM Houston. In fact, some research suggests that besides helping women with PCOS lose weight, the ketogenic diet may help rebalance their hormones - and in some cases help women who had previous infertility problems become pregnant on their own. In a small study published in the September-October 2018 issue of the journal AACE Clinical Case Reports, researchers followed four overweight women with PCOS who were trying to conceive follow a ketogenic diet, monitoring their progress monthly. Within six months, all four women lost weight, ranging from 19 to 36 pounds, and resumed regular menstruation (they’d all had irregular periods before they started the diet).
PCOS is a hormonal disorder in females that affects 1 in 10 women. It is largely characterized by having high male hormone levels (hyperandrogenism), infrequent ovulation and is the leading cause of infertility. While getting pregnant with PCOS can be a challenge, it’s very possible and adapting a fertility diet high in fat and low in carbohydrates is one of the best ways to help support fertility health.
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While the exact cause of PCOS is still unknown, PCOS is highly correlated with carrying excess weight, type 2 diabetes, previous gestational diabetes, and cholesterol problems - problems that are all linked to high insulin levels. It turns out that hyperinsulinemia can cause the ovaries to make testosterone and create other hormonal imbalances that reduce ovulation frequency and influence other PCOS symptoms.
Because insulin is released after eating a high carbohydrate meal, eating a low carb diet is one of the most effective ways to help support reduced insulin levels and has been shown to have a favorable impact on metabolic syndromes like PCOS. One recent study showed that every PCOS patient enrolled in a High Fat Low Carbohydrate fertility diet resumed regular menstruation and ovulation and half got pregnant naturally without the need of any medical intervention like ovulation induction, IUI, or IVF.
For women affected by polycystic ovarian syndrome (PCOS), changing to a ketogenic diet to reduce insulin levels may improve fertility. PCOS is a common disease that affects women in their childbearing age and includes irregular periods and high androgen levels combined with weight problems.
The ketogenic diet is a restrictive low-carb diet plan that focuses on low carbs, low fats and a normal amount of proteins. Patients often see weight loss results-which helps reduce PCOS symptoms-but women with PCOS see improvements because the problem in PCOS is carbohydrate/insulin resistance. “The link between insulin resistance and PCOS is very well studied,” says Ula Abed Alwahab, MD, an endocrinologist at Cleveland Clinic. “If we are able to control insulin resistance, then we are able to reduce many of the PCOS symptoms and complications, including weight, diabetes, high blood pressure, heart disease, and infertility.”
The Impact of Weight Loss on Fertility
Pre-conception weight is one of the major risk factors for fertility outcomes and it is well accepted that weight loss improves fertility in overweight and obese women. Women with a body mass index (BMI) >30 kg/m2 are classed as being clinically obese and have natural menstrual cycle disruptions at a rate of almost three times higher than women of a healthy weight. A positive relationship also exists between pre-conception body mass index and the time needed to fall pregnant in women who are overweight and obese. Carrying excess weight prior to conception can be an obstacle for obese women in getting pregnant, resulting in many women looking to healthcare professionals for assistance. Many overweight women who struggle with fertility have co-morbidities such as polycystic ovarian syndrome (PCOS) which poses additional challenges to fertility in itself due to disturbances in insulin resistance, sex-steroid metabolism and menstrual cycles. It has been estimated that 75% of infertile overweight or obese women have PCOS.
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It is well documented in the literature that weight loss can improve fertility and pregnancy outcomes, particularly involving in vitro fertilisation. The benefits to this patient cohort include more regular menstrual cycles, better quality embryos available for transfer, less dosage requirement for medications and the need for fewer treatment cycles. Pre-pregnancy weight loss has historically been centred on the traditional low fat, energy restricted diet plan. However the use of very low energy diets and low carbohydrate diets are increasingly being used to illicit more favourable weight loss and fertility outcomes.
Potential Benefits of Low-Carb Diets on Fertility Outcomes
The findings of these studies suggest that low carbohydrate diets warrant further research to determine their effect. Six of the seven studies assessed changes in reproductive hormones with all studies except Stamets and colleagues reporting significant improvements (p < 0.05). Mavropoulos (2005), Moran (2003), Palomba (2008) and Palomba (2010) all reported significant improvements in fasting insulin and testosterone, and although Thomson and colleagues reported an improvement in testosterone, their results were not significant. Moran (2003), Palomba (2008), Palomba (2010) and Thomson (2008) all investigated sex hormone binding globule and free androgen index, and all noted significant improvements with increased production of sex hormone binding globule and a consequential lowering of the free androgen index (p < 0.05). Moran (2003), Palomba (2008), Palomba (2010) and Thomson (2008) also investigated fasting glucose, and although all studies reported improvements, only Thomson and colleagues results were statistically significant. Four of the seven studies reported menstrual cyclicity, frequency of menses and/or ovulation rates. All of these studies illustrated a significant improvement in menstrual cyclicity and/or ovulation rates with a low carbohydrate diet.
Considerations and Potential Risks
While a ketogenic diet may help a woman who wants to get pregnant drop pounds quickly, it would be best to use it “to kick-start a new health routine and lose weight” before trying to conceive, Dr. Kudesia says, because you don’t want your body to be in a state of ketosis around conception (or any part of pregnancy). Also, for a healthy conception and pregnancy, it’s important to eat enough nutrient-dense whole foods, rather than to restrict calories, Cole says. Indeed, it can be hard to follow the keto diet in a healthy way, as many people eat foods high in saturated fat, such as butter and bacon, to stay in ketosis. Too much saturated fat can increase total cholesterol, which strains the heart, according to the American Heart Association. Another concern: Adhering to a restrictive diet like the ketogenic plan could add to a woman’s stress while she’s having fertility treatments, or it could have a negative impact on her relationship with food, Mallik says.
Some studies suggest that eating a low-carb diet before pregnancy is linked to a higher risk of certain birth defects, such as neural tube defects. Animal studies have similarly shown negative impacts on both heart and brain development. Other research suggests that very low-carb diets around the time of conception may be linked to a higher risk of gestational diabetes. Providers also have concerns about high levels of ketones during pregnancy. Some studies have connected long-term ketosis to possible effects on a baby’s development.
Dietary Recommendations for Fertility Enhancement
For these reasons, Rachelle Mallik, RDN, who specializes in reproductive nutrition in Chicago, believes that following the Mediterranean diet or a so-called Dutch-style diet- which emphasizes fruits, vegetables, meats, fish, whole-wheat bread (and cereals), and healthy fats - is a better approach to preconception because it has a more balanced distribution of macronutrients. So there’s no good reason to play the how-low-can-you-go game with healthy carbohydrates, she says.
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In general, a low carbohydrate diet can be safely followed while trying to conceive. Carbohydrate needs vary by individual. Reducing carbohydrate intake to 20% may work really well for some, while others may need to keep their carbs at 45%. Choose nutrient-dense carbs that have fiber and lots of vitamins and minerals. Eliminate foods that are refined and highly processed. These foods tend to include high amounts of simple carbs that are not supportive of general health or fertility. Choose quality protein sources too. When consuming meat, choose organic/grass-fed/antibiotic-free/free-range/hormones-free options if/when accessible to you. Great protein sources include chicken, turkey, beef, lamb, game meats, eggs, fish, and dairy.
The Fertility Diet - Low Carb / Slow Carb
Carbohydrates are our source of quick energy. They are rapidly metabolized into sugars which can be used to fuel our immediate energy needs such as in an exercise state or be immediately stored in the form of fats. It turns out that not all carbs are created equal. Fast carbs have a high glycemic index and are rapidly metabolized into sugars which cause weight gain and insulin resistance which in turn disturbs normal ovulation. Examples of fast carbs are white rice, white bread, potatoes, cookies, ice cream and sodas. Slow carbs are better for fertility and include brown rice, whole grain pasta and dark bread. Whole grains, vegetables and whole fruit all contain slow carbs.
Good Fats and Bad Fats
Some fats are healthy for you and needed by your body. These are called essential fatty acids. Many prenatal vitamins are fortified with essential fatty acids. Natural foods containing these fats include fish, fish oils, and some nuts. Most fats found in our food can be divided based on their chemical structure as saturated and unsaturated.
Choose vegetable oils (except coconut and palm kernel oils) and soft margarines (liquid, tub, or spray) more often because the combined amount of saturated fat and trans fat is lower than the amount in solid shortenings, hard margarines, and animal fats, including butter. Consider fish. Most fish are lower in saturated fat than meat. Some fish, such as mackerel, sardines, and salmon, contain omega-3 fatty acids, which are being studied to determine if they offer protection against heart disease.
Proteins
Proteins are what’s for dinner. These include the well-known animal proteins such as beef, pork, chicken and fish. In general, these are an important part of your diet and will lead to less weight gain than fats and carbohydrates. Less well known are vegetable proteins which appear to be better for your fertility. These include beans, peas and tofu (soy bean derivative). Peanuts and other nuts are also a good source of vegetable proteins. More protein intake, particularly from a vegetable source, can improve fertility.
Milk
Milk has been a source of controversy with some studies showing that it helps fertility and other studies showing a harmful effect. The most recent study show that two servings per day of whole milk or products of whole milk are beneficial. That could be in the form of a glass of milk and a cup of yogurt. In this study whole was better than skim. If your weight is increased, you may need to substitute skim milk since the effect of the weight is itself significant and unfortunately milk is rich in calories.
What About Fish and Mercury?
Large fish eat small fish and live a long time. In the process they accumulate mercury which is not healthy for pregnant women. However, small fish does not and is perfectly safe. Because this is confusing the Food and Drug Administration (FDA) suggests the following guidelines:
Do not eat shark, swordfish, king mackerel, or tilefish because they are particularly high in mercury. Eat up to 12 ounces (two average meals) per week of a variety of fish and shellfish that are lower in mercury. This would include shrimp, crab, scallops, oysters, cod, pollock, tilapia, fresh water trout, salmon and canned light tuna. If you choose albacore white tuna instead of canned light tuna, eat only up to 6 ounces (one average meal) per week.
Body Weight
There is no question that weight is a major factor affecting fertility. Most commonly the issue is high body weight, but in some cases low body weight can be a problem. There are many diets which can be of help. These range from the Atkins high protein diet to Weight Watchers or Jenny Craig. It is important to find some system that you believe in and to set modest goals such as a 10% initial weight loss. Remember that the first week of any dietary change is the hardest. After the first week, you will be more acclimated to this change and progress can begin. Too many carbs are frequently the problem with the modern convenience food diet. Remember, it is easier to gain weight from too many carbs than any other single category.
Exercise
Exercise was also shown to boost fertility. A reasonable plan is to set aside 30 minutes every day for exercise. This can be aerobic such as walking fast or running or muscle building such as working with weights. A mixture of both forms is probably the best. Anything is probably better than nothing. Remember that the longest journey begins with one step.
Foods to Increase Fertility
Ready to bust out your note pad and write down all these food that make it to the top of the fertile food list for their ability to increase your fertility and help you get pregnant?
Liver & Steak
While the sounds of a nice steak dinner is usually at the top of the list, the sound of eating liver probably isn’t. But if you’re serious about a fertility focused diet and eating foods to increase fertility, these two powerhouses should be on it. These two foods are a great source of protein and fat, AND they also just so happen to be great sources of vitamins (much more so than any superfood like blueberries or kale). Liver is a premium source of vitamins C, D, E, Co-Q10, Zinc, Folate, and fat - all of which have been shown to play crucial roles in male and female fertility. Given the incredible amount of nutrients liver packs, and similarly beef, they are two of the best foods you can eat to support fertility health.
Eggs
Eggs are another fertility superfood that are at the top of the list of foods to eat when trying to get pregnant. Eggs are packed with protein, Vitamins B12 (aka Folic Acid), E, Zinc, and fat. Protein and vitamin E have been shown to support the motility of sperm. Vitamin E is also known to affect overall sperm quality positively. Fertility specialists recommend ensuring appropriate vitamin E levels to support general male fertility and to help men with an unexplained reduction in semen quality. Most of the fertility-boosting nutrients in eggs are found in the yolk.
Eggs are also a rich source of Choline. The body needs to obtain a majority of its required choline from diet, as it can only naturally produce a limited amount. Choline is known to reduce the risk of some birth defects. Doctors and fertility specialists recommend ensuring appropriate choline levels before and throughout pregnancy to help with proper fetal development.
Salmon, Sardines, and other High Omega-3 Fish
Salmon is an oily fish that is packed with protein, omega 3s, and essential fatty acids known to help support both male and female fertility and are great foods to eat when trying to get pregnant. Omega 3s are vital for human cell production and they help balance the reproductive system. Omega 3s help to support sperm production in males and to maintain oocyte quality in females. Salmon contains high levels of vitamin D. Vitamin D has been shown to play an important role in supporting male and female general and reproductive health. Achieving appropriate vitamin D levels can be very difficult, especially during the winter months when there is less sun. In fact, Vitamin D deficiency affects about 40% of Americans. Vitamin D deficiency has been shown to negatively impact both male and female fertility.
Salmon is rich in iodine, as is other seafood. Research has shown that iodine deficiencies have been linked to reduced fertility. In one study, those with iodine deficiency were shown to have a 46% lower chance of getting pregnant each month.
Pork Belly
Pork belly is packed with fat-soluble vitamins and minerals. It is known as “the better bacon” because the two taste similar, but pork belly has more healthy fats and meat. Pork belly is about 30% fat, and a single oz contains 15 g of fat. This fat is loaded with B vitamins known to help support fertility.
Pork contains selenium, which has been demonstrated to support reproduction in both men and women. Selenium is an antioxidant that supports healthy follicles in the ovaries, which develop and release eggs. Research has shown that low selenium levels may be a factor in miscarriages. In men, selenium has been shown to help support sperm motility.
Butter
Butter is a key ingredient to Dr. Kiltz’s Keto diet, also known as the B.E.E.B.I (Bacon, Eggs, Butter, Beef, Ice Cream - pronounced baby) diet. High-fat butter contains high levels of cholesterol. Cholesterol is needed to make many critical fertility hormones and to fight inflammation. The liver produces 75% of the cholesterol that the body needs; the remaining 25% must be achieved through diet. Cholesterol is a major component of breast milk and is essential for baby’s growth and development.