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This is a guest post by Laura Schoenfeld, a Registered Dietitian with a Master’s degree in Public Health, and staff nutritionist and content manager for ChrisKresser.com. You can learn more about Laura by checking out her popular blog or visiting her on Facebook.

Carbohydrates, and the role they play in a healthy diet, are one of the most hotly contested nutritional debates in the world, both in conventional and ancestral health circles.

On one side, you’ve got folks who say that carbohydrates are nonessential and increase your risk for diseases such as diabetes, cancer, and neurological disorders. On the other side, some say that carbohydrates are crucial for good health and should make up the majority of your calories.

It’s no wonder I have so many clients who come to me completely confused about carbs and whether or not they should eat more or less of them.

is a low carb diet ruining your health

While some people do incredibly well following a low carb Paleo diet, there are many people who crash and burn on this type of dietary plan. So, how can you tell if you’re the type of person who shouldn’t be eating a low carb diet, and how do you figure out how many carbs you should be eating? I plan to teach you just that in this article.

Is your low-carb diet doing you more harm than good? Find out how many carbs YOU should be eating.

Pregnancy

I recently discussed the role of carbohydrates during pregnancy in an episode of The Ancestral RDs Podcast. The most important reason why women need adequate carbohydrates during pregnancy is to ensure adequate fetal brain development and growth. Another reason is because a high protein diet can be dangerous during pregnancy, and when you cut out carbohydrate as a major macronutrient, you usually can’t help but increase protein as a percentage of calories. Protein intake greater than 25% of calories during pregnancy may lead to decreased mass at birth and increased perinatal morbidity and mortality for the baby.

The Institute of Medicine recommends a minimum of 175 grams of carbohydrates per day during pregnancy, which is 29% of calories on a 2400 calorie dietPaul Jaminet advises pregnant mothers to restrict protein to about 15% of calories and to obtain 30% of calories as carbohydrates. Chris recommends a moderate carb approach for most pregnant women (except those with any type of diabetes) in his book, Your Personal Paleo Code.

Like these other experts, I generally recommend 30% of calories from carbohydrates for my pregnant clients, and also for those who are struggling with fertility. Unless you have diabetes or a serious neurological condition that requires carbohydrate restriction, it’s not worth the risk playing around with a low carb diet when you’re pregnant, and these diets aren’t conducive to fertility for many women either. (If you’re interested in more reasons why carbohydrates can affect fertility, read this great post by Stefani Ruper.)

Athletes

If you’re a professional or recreational athlete who trains hard 4, 5, or even 6 days per week (I hope you’re not doing 7 days per week!) and trying to maintain this level of activity on a low carb diet, you may be doing more harm than good to your health and fitness.

While there are athletes who thrive on a well-planned low carb approach (LeBron James most recently!), there are many others who do not. Each athlete is completely unique in their ability to perform well on a low carb diet, and there’s nothing wrong with testing out the diet to see how it affects your athletic ability.

But if you’ve been trying a low carb diet for months now and your workouts are suffering, your weight isn’t budging (or maybe you’ve even gained weight!), and your recovery time is increasing, you’re probably not the type of person who can handle a low carb diet combined with regular intense physical activity.

I’ve had many clients come to me on a low carb diet who, after switching to a more moderate carb approach, found that their energy and endurance significantly increased, and they were able to make quicker strength gains than before. Many also were able to shed some of the stubborn body fat that they’d been retaining despite eating a low carb diet and training hard, which was a result they didn’t expect!

For my athletic clients, I usually recommend a minimum of 20% of calories from carbohydrate, and depending on the person’s health goals, training schedule, and current issues, I may actually recommend more like 40-50% of calories from carbs.

Again, each athlete is an individual and what works for one person, or even a thousand people, may not work for you. So don’t be afraid to experiment and pay attention to how your diet makes you look, feel, and perform! And don’t hesitate to get help if you need it!

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Hypothyroidism and HPA Axis Dysregulation (Adrenal Fatigue)

Hypothyroidism is one of the most commonly cited medical reasons for needing to eat a moderate carb diet. The main reason why carbs affect thyroid function so directly is because insulin is needed for the conversion of the inactive T4 hormone into the active T3 hormone, and insulin is generally quite low on very low carbohydrate diets.

So if you’ve suddenly started developing hypothyroid symptoms on your low carb diet, it’s a pretty good sign that you’d be better off upping the carbs (and getting your thyroid tested if you haven’t already!) For more about how low carb dieting affects your thyroid, listen to this great interview with Chris by Jimmy Moore.

HPA axis dysregulation, also known as adrenal fatigue, is another condition where a moderate carb intake is important for general health. Kelsey and I talked about adrenal fatigue on our first Ask the RD podcast, so listen to it if you’re unfamiliar with this condition. The main hormone that gets dysregulated in adrenal fatigue is cortisol, and cortisol has been shown to increase on a low carb diet. This means that a low carb diet is a potential adrenal stressor in susceptible individuals. Combine that with a stressful job, inadequate sleep, and overexercise, and you’ve got yourself a recipe for adrenal burnout.

So if you have adrenal fatigue, or if your current lifestyle is already high stress in a few different areas, you may want to increase your carb intake until you can get those additional stressors under control, as you may drive yourself into adrenal fatigue by having a chronically elevated cortisol output. Lara Briden has written a great article on the benefits of whole food carbohydrates in lowering cortisol and raising GABA, a calming hormone that is often low in adrenal fatigue patients.

If you’re experiencing symptoms of hypothyroidism or adrenal fatigue, you may be worsening them with a well-intentioned low carb Paleo diet. I recommend working with someone to help you figure out if your diet is indeed making these symptoms worse, and how to change what you eat to better support your thyroid and adrenal health.

Gut Health

One of the less discussed downsides of a very low carbohydrate diet over the long run is the potential for alteration of the gut flora. Chris recently covered this issue in a podcast with Jeff Leach, where they discussed evidence that a very low carb diet can lead to gut dysbiosis and a reduction in the diversity of the gut flora. A lot of the information on this topic is new and not fully understood, but it’s reasonable to believe that when you avoid carbs, you’re also avoiding important prebiotics (i.e. food for your gut flora) like soluble fiber and resistant starch.

These prebiotics are essential for promoting the growth of beneficial gut flora. Without them, your beneficial flora can’t produce as much gut-healing substances like butyrate and other short chain fatty acids, and your microbiome composition may even shift in an undesirable direction. And as Chris would say, you’re only as healthy as your gut is: an unhealthy gut contributes to everything from obesity and diabetes, to digestive illness, to autoimmune disease, to skin disorders.

Those who are doing very low carbohydrate diets, and who simply can’t increase their starch intake for whatever reason, should use prebiotic supplements such as resistant starch-rich unmodified potato starch or FOS powder. However, these products must be incorporated slowly into your supplement regimen, as you can experience severe gas and bloating if too many prebiotics are taken all at once, or if there is existing gut dysbiosis or bacterial overgrowth. In this case, it would be wise to work with someone who can help you get the prebiotics you need while on a very low carbohydrate or ketogenic diet to protect the health of your gut microbiota.

How Many Carbs Do I Need?

To determine how many carbs my clients need to eat in a day to reach their health goals, first I decide what percentage of calories from carbs they’d possibly do best with. As an example from above, a woman struggling with fertility issues may benefit from a carb intake around 30% of calories. I then determine her caloric needs using a calculator like this one. If we determine that her daily needs are roughly 2000 calories per day, 30% of calories from carbs is 600 calories. As there are 4 calories in a gram of carbohydrate, this works out to be 150 grams of carbs per day.

Usually I give my clients a target range to hit depending on their activity levels, and we use these targets to re-evaluate their food diaries and see if they’re hitting their goals. Most of my clients are surprised to learn how much carb-rich Paleo foods they have to eat to get up to 150-200 grams per day! But once they start making a real effort to hit those targets, the health benefits are immediate.

These benefits include weight loss, elevated mood, skin improvements, increased energy, normal menstrual function, more satisfying sleep, and more. It’s so exciting to see what a couple of starchy tubers and pieces of fruit can do for a person’s health when they simply need to eat more carbs!

Wondering what foods have carbs in them, and what portion sizes you need to eat of each type to get the carbs you need? Click here for a handy list you can print out!

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Final Thoughts

The purpose of this article was not to bash low carb diets. I truly believe that there are many people out there who get amazing health results from a low carb plan, and there are dozens of health conditions that benefit from a very low carb or ketogenic diet, especially severe neurological conditions. Paul Jaminet has written some great posts explaining when a ketogenic diet may be useful and necessary, so I strongly suggest reading those posts if you’re still on the fence about where you stand with carbohydrates and your health needs.

My hope is that by reading this article, you’ll be able to understand the many factors that play into how a person handles a low carbohydrate diet, and whether or not their health will improve on such a plan. Everyone is different in their ability to thrive on a low carbohydrate diet. If you’ve found yourself identifying with any of the issues I’ve written about in this post, you may be in need of a macronutrient adjustment in your diet.

Helping people optimize their carb intake is a challenge I truly enjoy. As a dietitian, I love to help people evaluate their diet to determine if they’re meeting their health needs with the food they’re eating. If you think you could benefit from a Paleo diet makeover, I’d love to chat with you about where you’re at and where you want to go with your health.

Your carb intake shouldn’t be the major factor that’s preventing you from reaching your health goals. I hope you use the information I’ve shared today to evaluate your own nutritional needs and make the changes that make sense to you.

Now I want to hear your story. Have you experienced health benefits from increasing your carb intake? Share what you’ve learned in the comments below!

Laura Schoenfeld MPH RDAbout Laura: Laura uses her knowledge of traditional and biologically appropriate diets to improve her clients’ health. Growing up with a family that practices Weston A. Price principles of nutrition, she understands the foods and cooking practices that make up a nutrient dense diet.

With her strong educational background in biochemistry, clinical nutrition, and research translation, she blends current scientific evidence with traditional food practices to help her clients determine their ideal diet.

You can find her at AncestralizeMe.com, on Facebook, and Twitter!

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