How Keto Can Kill Your Thyroid (& What to Do Instead)
By Amiee McNew
While the keto diet’s low-carb lifestyle has been touted as a successful way to lose weight, if you have existing thyroid problems, then going keto can do more harm than good.
The ketogenic diet is getting a lot of buzz lately for its ability to reduce inflammation, promote rapid weight loss, and even reverse certain chronic conditions like epilepsy.
That leads people with thyroid problems to wonder if going Keto could finally help them lose weight, balance their hormones, and reverse all the unpleasant symptoms associated with an over – or underactive thyroid. Yet, is Keto really the right nutritional approach for thyroid wellness?
The Keto diet is based on the principle of switching the body from being glucose-fueled to being ketone-fueled. Glucose is broken down from carbohydrates and excess proteins in the diet and is used to provide cellular energy. When excess glucose is present, it gets stored as fat for later use. However, when excess glucose is eaten on a regular basis, this can become a recipe for being overweight or obese, or for having insulin resistance, metabolic syndrome, or even diabetes. (1)
The ketogenic diet switches the primary source of cellular energy to ketones, which are produced when there is a significant deficit of glucose. Ketones are made when the body’s primary food source is fat, followed by protein, and then in a much more restricted manner, carbohydrates. (2)
Keto is a food plan that limits carbs and relies on fat and moderate protein intake to create an alternate fuel source. This has therapeutic implications for a number of conditions, including epilepsy and diabetes.
People on a ketogenic diet eat varying levels of carbs based on their genetic individuality, activity level, health goals, and even gender. Women tend to require more carbs than men, and highly active folk can get by with higher carb intakes while still maintaining ketosis. A ketogenic diet is not a zero carb diet. In fact, most on a Keto plan will aim for between 30 to 50 net carbs per day. In contrast, a low carb but not ketogenic diet might aim for 100 net carbs daily. (3)
When glucose is removed as the primary fuel source and ketones fuel the body, significant impacts on inflammation and other chronic conditions, like diabetes, can be made. (4) The health benefits are clear, but do they benefit all health conditions or just specific ones?
Bottom line: Keto is a food plan that limits carbs and relies on fat and moderate protein intake to create an alternate fuel source. This has therapeutic implications for a number of conditions, including epilepsy and diabetes.
Why Isn’t Keto Good for Thyroid Problems?
The thyroid is a small organ that is found at the base of the neck which is responsible for producing the hormones that regulate metabolism. But the thyroid also plays a key role in reproductive health, body temperature regulation, mood, and immunity. When the thyroid isn’t functioning as it should be, the symptoms can be severe and felt in nearly every aspect of wellness. People desperate to feel better from a thyroid condition may even be willing to quit carbs entirely, thinking that Keto could fix them.
The problem with this is that when thyroid dysfunction is truly the cause of health problems, especially when it is hypothyroid, or a low functioning thyroid, dramatically cutting out most carbs can further suppress the thyroid’s ability to do its job.
The thyroid needs glucose to produce its hormones T3 and T4, and to convert these hormones from inactive to active form. When not enough carbs are present, hormone production and conversion slows, which can worsen a hypothyroid condition, including those caused by autoimmune thyroid disease. (5)
The thyroid needs glucose to produce necessary hormones and to convert inactive forms into active, usable ones. A ketogenic diet doesn’t supply the right form of energy to make a thyroid function optimally if it is struggling.
What confuses people is that it’s best for thyroid health to avoid junk carbs and refined sugars and flours. These are empty foods that offer no nutritional value, and which can contribute to metabolic problems and weight gain thanks to a sluggish thyroid. Quality wins out every time with carbs and the thyroid, so when it comes to thyroid wellness, it isn’t cutting them out and focusing on ketones that matters – it’s ensuring that you’re choosing the best carbohydrates to be your body’s fuel.
The other problem with carbs is that cutting them suddenly from the diet – as tends to happen when making an abrupt dietary shift like starting a ketogenic diet – can trigger the production of another thyroid hormone known as Reverse T3. If it sounds like the opposite of T3, the primary energy-boosting thyroid hormone, it is. (6)
Reverse T3 is produced when the conversion of inactive T4 doesn’t happen as it should. As a result, Reverse T3 is made. T3 causes the body to have a great metabolism, shed extra weight, and have an energetic, balanced mood – Reverse T3 causes the opposite. It prompts the body to go into fat storage mode, produces sluggish and sleepy feelings, and can have a depressing effect on your mood. It can also interfere with healthy insulin usage, leading to weight gain, especially in the middle. (7)
Bottom line: The thyroid needs glucose to produce necessary hormones and to convert inactive forms into active, usable ones. A ketogenic diet doesn’t supply the right form of energy to make a thyroid function optimally if it is struggling, and can lead to the production of Reverse T3, an anti-energy thyroid hormone that can worsen the symptoms and lead to weight gain.
3 Ways to Support a Low-Functioning Thyroid That Work Better Than Keto
If you’re struggling with low thyroid function, finding the right solution for you can be a challenge. While certain kinds of extreme dietary changes can boost thyroid function, others can harm it. Here are the best ways to boost a thyroid without leading to a keto-induced drop-off.
1. Eat The Right Kind of Carbs
If you have a thyroid that isn’t functioning optimally, then you need carbs. When most thyroid patients hear that, they run off to eat some cookies and cake. The reality is, carbs are essential for thyroid hormone production. However, the wrong type of carbs will lead to hormone problems, as well as extra side effects of weight gain, insulin issues, and even oxidized cholesterol. (8)
Refined and processed carbs like grains, flours, and sugars should be strictly avoided. If you want to make a “cold turkey” dietary switch for thyroid health, start by removing these foods from your diet. Note, this does not mean that you should stop eating carbs altogether. Instead, replace them with high-quality carb sources like vegetables, fruits, nuts, and seeds. You can even enjoy very moderate amounts of Paleo-friendly sweeteners like raw honey and maple syrup, which also offer nutritional benefits.
While each individual’s carb counts for thyroid wellness will differ, most won’t want to go any lower than 150 grams per day. Some may need closer to 200, depending on their age, weight, condition of their thyroid, and other factors like if you’re a very active person, or trying to get pregnant or breastfeeding.
Refined and processed carbs like grains, flours, and sugars should be strictly avoided. Instead, replace them with high-quality carb sources like vegetables, fruits, nuts, and seeds.
Keep in mind that when eating these high-quality carbs, you also need to pair them with high-quality protein and fat. Eating carbs on their own, even quality ones, can lead to insulin problems in people who already have compromised hormone function – including thyroid issues. While you don’t have to get crazy and measure your macros all the time, just know that when eating carbs, you should also eat at least one whole serving of protein or healthy fat, or both.
Ideal sources of protein include eggs, grass-fed meats, and wild-caught fish, as well as nuts, seeds, bone broth or collagen powder.
Fat sources can vary, but you want to make sure that you’re regularly eating omega-3 sources of fatty acids, like salmon, mackerel, herring, and sardines. Non-fishy sources of omega-3s include chia seeds and walnuts, both of which are Paleo and thyroid superfoods.
2. Supplement Nutrient Deficiencies
With thyroid issues, certain nutrient deficiencies seem to be common, and just eating a whole foods diet might not be enough to correct them in a timely manner. You can boost your thyroid function and wellness with several common supplements. Even though these supplements are all available over the counter, it’s best to get personalized recommendations on brands and dosages from qualified practitioners who can best advise you. How can you know if someone is qualified to help you figure this out? Find a certified or otherwise well-credentialed nutritionist, nutrition therapist, naturopath, or integrative MD who can explain what Reverse T3 is to you. In my experience, if a practitioner can’t tell you about Reverse T3 and what it does within the body, then they aren’t well-versed enough in thyroid health.
The top nutrient deficiencies associated with thyroid problems are common to many other chronic conditions, too.
Magnesium: Most American adults are low in this critical mineral, and testing levels before supplementing isn’t typically required. Choosing a bioavailable form of magnesium is, however, so opt for either magnesium glycinate or magnesium chelate. Dosing can range from 100 to 400 mg, so it’s best to get a personalized recommendation from a practitioner. In general, start with the smallest dose, which is typically one capsule ranging from 100 to 200 mg. Magnesium can benefit numerous thyroid symptoms and side effects like anxiety, chronic fatigue, body pain, headaches, and sleep problems. (9,10)
Zinc: Another essential mineral, zinc deficiency is also common in the American adult. Zinc is essential for thyroid hormone production and conversion. Most multivitamins contain zinc, but it can at times be beneficial to take extra, under the direction of a practitioner. (11)
Selenium: Selenium is a trace mineral that functions as an antioxidant within the body and supports thyroid function and hormone production. Without the right selenium levels, hormone conversion suffers. (12) This is sometimes found in multivitamins, but can typically be taken as a separate supplement too, especially in the initial phase of trying to rebalance thyroid wellness.
Vitamin D3: Between the months of October and March, most who live in the northern hemisphere don’t get adequate sun exposure to keep their D levels high enough. Lack of vitamin D can hamper thyroid function, and a deficiency should be corrected immediately. Most practitioners agree that a 5,000 IU daily dose is good for maintenance, but levels should still be tested to ensure that a higher dose isn’t needed. Since vitamin D is fat soluble, it can accumulate in the body, and shouldn’t be supplemented at higher doses unless a practitioner has tested and advised otherwise. Choosing D3 instead of D2 is also critical for absorption and usability. (13)
A Note on Curcumin: Another supplement not essential for nutrient deficiency, but which can have stellar anti-inflammatory results in the body and can be especially beneficial for autoimmune thyroid problems is curcumin. Derived from turmeric, this supplement is usually paired with black pepper for optimal integration, and can also benefit other thyroid issues like a depressed mood, aches and pains, and even sleep problems. (14)
3. Get the Right Kind of Thyroid Support
While it’s possible to reverse hypothyroidism without medication, in many cases it’s faster and just as safe to support the thyroid with a boost of either T3, T4, or both. This can only be done with a prescription and a doctor’s authorization but, as a patient, you can be informed when it comes to making decisions about your medication.
There are several forms of thyroid medication available, but the three common ones are:
Synthetic T4: This supplies the body with synthetic T4, the inactive form of the thyroid hormone. For people struggling to produce enough of this base thyroid hormone, this can boost function but if conversion problems are present in the body or reverse T3 is high, this medication form can either go unconverted or can be converted into higher levels of RT3.
Synthetic T3: This supplies the body with synthetic T3, the active form of the thyroid hormone. While it doesn’t require conversion, it can also quickly result in higher hormone levels and has more potential for side effects and dosing nuances.
Desiccated thyroid: This is thyroid medication derived from animal sources that contain both T3 and T4, most closely mirroring our own thyroid hormone production. It can help elevate T4 stores while reducing the sudden burden of needing to convert more hormones to T3, but it can also be harder to dose properly in patients who really only need one or the other.
The important factor in thyroid medication is to communicate openly with your doctor and to get your thyroid levels regularly tested. Initially, doses may need to be adjusted several times a year. Once the source of hypothyroidism is reversed, medication needs may diminish, or if the thyroid is permanently struggling because of autoimmune damage, dosing becomes more stable as your body sinks into a rhythm with its new additional support.
Thyroid problems require specific nutrient and dietary intervention to rebalance, and it’s not as simple as cutting carbs or getting on medication. Medication is not a quick fix but works in conjunction with other dietary and lifestyle factors. While the Keto diet isn’t generally appropriate for those with thyroid problems, a Paleo diet, free from common allergens and refined products, can often be a therapeutic plan that helps reverse thyroid symptoms for the long haul.