Most people are told a simplified explanation of thyroid physiology. They are told that if they reduce carbohydrates their thyroid function will decline and that carbohydrates are required for a healthy thyroid. When they lower carbohydrates and begin to feel fatigued, cold, anxious, or experience menstrual or sleep disruption it is easy to attribute all of those changes to carbohydrate intake alone. But in this blog post we are going to talk about how thyroid physiology is way more complex than that, what the state of the literature is about your thyroid needing carbs and what levers for thyroid  health and healing you are not pulling that could really make a difference. And I would argue, more importantly, allow you to not be dissuaded from using a ketogenic diet as a treatment for mental illness if you have exhausted your other treatment options, or if you are just plain exhausted, and want to explore the hope and promise of ketogenic diets for yourself.

Rethinking “Your Thyroid Needs Carbs”

First, we need to talk about why you need to be mindful of your light exposure. Your thyroid hormone production, conversion, and receptor sensitivity are strongly regulated by light exposure, mitochondrial function, and circadian timing. The hypothalamic pituitary thyroid axis responds to sunrise light, daytime light exposure, and darkness at night. Melatonin production during dark hours supports mitochondrial repair in the thyroid gland, liver, and brain. In that context, carbohydrates are one input among many, not the primary regulatory signal. Your melatonin production is tightly linked to darkness and that melatonin is concentrated in and acts within mitochondria, literally a hormone that is synthesized in the dark. You don’t want to short change yourself on melatonin, because it has very important regulatory and antioxidant actions that exert direct effects on mitochondrial function in multiple tissues including your brain. It is in particularly high concentrations inside mitochondria and acts as a potent antioxidant that supports mitochondrial redox balance and protects respiratory chain complexes and mitochondrial DNA.

What do mitochondria do?

So what’s my point? You thought this was a blog post about thyroid, right? What does melatonin have to do with thyroid function, anyhow?

Because proper exposure to natural light throughout the day helps regulate your melatonin production, which then has direct effects on maintaining a healthy thyroid or healing one. Melatonin protects thyroid tissue from oxidative injury and is being investigated as a protective factor in thyroid disease. Experimental work in animals and ex vivo thyroid tissue demonstrates that melatonin reduces oxidative damage to thyroid membranes and may protect against toxic or carcinogenic insults to the gland. Even though most of these studies measure oxidative stress markers and functional outcomes rather than direct imaging of “mitochondrial repair,” the pattern is consistent with melatonin as an antioxidant supporting mitochondrial integrity and redox homeostasis in the thyroid.

Thyroid Hormones, Mitochondria, and Metabolic Stress

Thyroid hormones work through mitochondria. If electron transport is impaired, membranes are damaged, or redox status is poor, simply adding more carbohydrate or more thyroid hormone can increase metabolic stress rather than improve efficient energy production.

Stephen Phinney’s Virta Health article “Does Your Thyroid Need Dietary Carbohydrates” is not peer reviewed but accurately summarizes a pattern clinicians working with low carbohydrate populations see and argues, based on Bisschop and his own early ketogenic trials, that lower T3 with preserved resting metabolic rate and clinical status is best explained by improved thyroid hormone sensitivity on a well-formulated ketogenic diet. This is further supported with a mechanistic hypothesis put forth by Vranjić et al. of altered thyroid hormone sensitivity in nutritional ketosis.

Medical providers are not necessarily aware of the discussion going on around thyroid hormone and low carb populations, leading to thyroid hormone supplementation that is either inappropriate or doses that are potentially harmful. In experimental systems and in humans receiving TSH suppression therapy, hyperthyroid states increase mitochondrial oxygen consumption and reactive oxygen species and can impair oxidative phosphorylation efficiency and damage cellular structures. In an already stressed system, pushing thyroid hormone dosing toward hyperthyroidism is more likely to increase metabolic strain than to restore efficient energy production.

What Your Thyroid Needs on a Ketogenic Diet

Myths about the need for carbohydrates to make adequate hormone levels aside, it is important to understand that your thyroid can function on a well-formulated ketogenic diet when you give it the basic things it needs. For example, there is something called a diet–gut–thyroid axis that requires iodine, selenium, iron, zinc, copper, magnesium, vitamin A, and vitamin B12 as key requirements of thyroid hormone synthesis and regulation. A well-supported thyroid needs not just those nutrients, but regular sunrise and morning light exposure, darkness and reduced artificial light in the evening, adequate protein intake, healthy fats, and improved stress management that reduces chronic sympathetic overactivation.   

When someone reduces carbohydrates and then experiences symptoms such as feeling wired and tired, cold extremities, insomnia, anxiety, or palpitations, this can often be as simple as they are using an insufficient or ineffective electrolyte protocol. But assuming your electrolyte protocol is on point, these symptoms that are often attributed to thyroid dysfunction may indicate a system that was most likely already under strain. These types of symptoms appearing with the reduction of carbohydrate indicate a metabolism that has temporarily lost its resiliency.

Many people attempting a ketogenic diet will report that they cannot fall asleep without carbohydrates in the evening. In a dysregulated system this often reflects a pattern where maladjusted circadian timing exists. It is often reflected as cortisol being low when it should be higher in the morning and elevated when it should be declining at night, resulting in the nervous system being persistently activated. So when that sort of thing is going on and your functional practitioner tells you to eat carbs at night and you feel better, it makes you think they might be correct that you “need” carbohydrates. They are not. However, I do not disbelieve you when you tell me that the carbs helped you feel better. In stress vulnerable individuals, carbohydrate rich, protein poor intake can acutely raise insulin and increase brain tryptophan and serotonin availability, and blunt cortisol responses.

Sure, carbohydrates can function as a compensatory tool that temporarily helps sleep or feeling stressed, but they do not correct the underlying nutritional, circadian and mitochondrial problems that drive thyroid related symptoms. Thyroid physiology is responsive and reflects the cumulative signals it receives. Nutrients are a signal. Light is a signal. Darkness is a signal. Your perception of something being stressful is a signal. Current reviews of diet and thyroid function continue to report that different macronutrient patterns can be associated with changes in measured thyroid hormone concentrations. However, the available studies are few, methodologically inconsistent, and often confounded by weight loss and energy restriction.

Overall, what the literature does support is the conclusion that nutrition influences thyroid physiology through multiple interacting factors rather than through any single macronutrient ratio. I don’t know how to say it any clearer. Current evidence does not support the claim that thyroid function is governed by specific dietary macronutrient ratios. Your thyroid function does not operate in isolation from the rest of your body. It depends on how well mitochondria in the thyroid gland, liver, and brain are working and on how well the hypothalamic pituitary thyroid axis is aligned with natural light, dark cycles and required nutrients.

In the literature, mitochondrial dysfunction is described both as a consequence of abnormal thyroid status and as a factor that can worsen or perpetuate thyroid disturbances. In other words, thyroid function and mitochondrial capacity are tightly linked rather than independent processes. You may think that if your thyroid is already struggling you will never have mitochondrial health, but that is not the case. This connection also means that you have leverage through the signals that support mitochondrial function rather than through carbohydrate intake alone. Chronobiology research shows that the hypothalamus, pituitary, and thyroid express clock genes and that thyroid hormone secretion follows a daily rhythm anchored to environmental light and dark signals. The research literature is far more developed on the roles of micronutrient status, total energy intake, illness burden, and overall metabolic state in thyroid function than on the idea that your thyroid “needs carbs” to function.

When Ketogenic Therapy Supports Thyroid Health and Recovery

In fact, ketogenic diets may be of particular benefit to individuals with thyroid dysfunction when they are implemented and monitored correctly. Ketogenic nutrition improves insulin sensitivity, lowers systemic inflammation, and alters deiodinase activity in ways that can reduce the inflammatory and oxidative burden on thyroid tissue, including in autoimmune conditions such as Hashimoto’s thyroiditis.

Taken together, these effects suggest that the KD supports thyroid health by reinforcing mitochondrial resilience and redox balance.

Vranjić, P., Vuković, M., Blažetić, S., & Viljetić, B. (2025). Ketogenic Diet and Thyroid Function: A Delicate Metabolic Balancing Act. Current Issues in Molecular Biology, 47(9), 696. https://doi.org/10.3390/cimb47090696

The mighty ketone beta hydroxybutyrate (BHB) can enhance mitochondrial efficiency and redox balance, support regulatory T cell function, and shift immune activity away from Th17 dominated responses that damage the thyroid, helping to stabilize autoimmunity rather than worsen it. That effect, along with the ketogenic diets ability reduce obesity related TSH elevation and improve metabolic profiles that strain the thyroid can be a life saver. How? Because in preclinical models ketogenic diets may slow the growth of aggressive thyroid cancers by exploiting their dependence on glycolysis while ketone bodies exert additional antiproliferative and pro differentiation effects at the cellular level. The overall synthesis of the evidence is that ketogenic diets do not inherently harm the thyroid and may provide a useful therapeutic option for those with thyroid disease.

Mitochondrial Health and a Ketogenic Diet

If your functional nutrition or medicine provider insists that additional carbohydrate is required for thyroid function while giving little attention to mitochondrial health, circadian organization, and redox status, they are not working from a root cause framework. People who are using ketogenic metabolic therapy for psychiatric and neurological recovery can proceed with these foundational metabolic interventions even when their clinicians are unfamiliar with this literature. As mitochondrial function improves through changes in light exposure, sleep, nutrition, and nervous system regulation, the likelihood of a well-formulated ketogenic nutrition intervention leading to more stable thyroid physiology increases.

Nobody is taking your carbs away from you. If you feel like you need them strategically in your healing journey with the guidance of your medical providers, by all means do carry on. And if you and your medical provider decide that you should not wait to implement these therapies and choose thyroid hormone supplementation, far be it from me to argue. But I do hope you will self-advocate and share some of the knowledge you learned here about how ketogenic populations may have a difference in thyroid hormone markers and function that still need to be fully investigated but must be medically considered. This blog post really wasn’t written with you in mind. Although I am happy if you learned something you might find helpful in your healing journey.

Your Recovery Is Bigger Than Thyroid Myths

This blog post was written for those suffering from mental illness, who may have wanted to explore the hope and promise of what a ketogenic diet could do for them towards their goal of  psychiatric recovery. Do not continue to be afraid to implement a ketogenic diet with your treatment team because of poorly substantiated opinions and clinical theories that your thyroid will not work without carbs. You have every reason to expect that doing your ketogenic diet while pursuing natural light exposure, sleep quality, nutrient status that includes iodine, protein intake, healthy fats, adequate energy intake and chronic stress reduction will leave you with not only healthy mitochondria and thyroid function, but a solid foundation toward your goal of psychiatric recovery.  

Your fear is understandable, but misplaced. Your physiology is not broken beyond repair. The story you were given about your thyroid is too narrow and too disconnected from the evidence. You are allowed to pursue a therapy that may help you think more clearly and suffer less without being stopped by myths about carbohydrates. You have more power than you were told. A well–formulated ketogenic diet can be an ally in your healing when it is supported by light, sleep, nutrients, and nervous system regulation. Your recovery is not only possible, it deserves a full and informed attempt.

Keep going.

Brain Fog Recovery Program

References

Afaghi, A., O’Connor, H., & Chow, C. M. (2007). High-glycemic-index carbohydrate meals shorten sleep onset. The American Journal of Clinical Nutrition, 85(2), 426–430. https://doi.org/10.1093/ajcn/85.2.426

Aggarwal, A., Yuan, Z., Barletta, J. A., Lorch, J. H., & Nehs, M. A. (2020). Ketogenic diet combined with antioxidant N-acetylcysteine inhibits tumor growth in a mouse model of anaplastic thyroid cancer. Surgery, 167(1), 87–93. https://doi.org/10.1016/j.surg.2019.06.042

Bisschop, P. H., Sauerwein, H. P., Endert, E., & Romijn, J. A. (2001). Isocaloric carbohydrate deprivation induces protein catabolism despite a low T3-syndrome in healthy men. Clinical Endocrinology, 54(1), 75–80. https://doi.org/10.1046/j.1365-2265.2001.01158.x

Ceylan, Ö. Ö., Yılmaz, B., & Süzen, S. (2024). Evaluating the Role of Melatonin on Thyroid Physiology and Diseases. Journal of Faculty of Pharmacy of Ankara University, 48(3), 1281–1292. https://doi.org/10.33483/jfpau.1504455

Cipolla-Neto, J., & Amaral, F. G. do. (2018). Melatonin as a Hormone: New Physiological and Clinical Insights. Endocrine Reviews, 39(6), 990–1028. https://doi.org/10.1210/er.2018-00084

Does Your Thyroid Need Dietary Carbohydrates? (2025, May 2). Virta Health. https://www.virtahealth.com/blog/does-your-thyroid-need-dietary-carbohydrates

Gładysz, A. K., Stępniak, J., & Karbownik-Lewińska, M. (2023). Exogenous Melatonin Protects against Oxidative Damage to Membrane Lipids Caused by Some Sodium/Iodide Symporter Inhibitors in the Thyroid. Antioxidants, 12(9), 1688. https://doi.org/10.3390/antiox12091688

Güemes, A., & Georgiou, P. (2018). Review of the role of the nervous system in glucose homoeostasis and future perspectives towards the management of diabetes. Bioelectronic Medicine, 4(1), 9. https://doi.org/10.1186/s42234-018-0009-4

Iacovides, S., Maloney, S. K., Bhana, S., Angamia, Z., & Meiring, R. M. (2022). Could the ketogenic diet induce a shift in thyroid function and support a metabolic advantage in healthy participants? A pilot randomized-controlled-crossover trial. PLOS ONE, 17(6), e0269440. https://doi.org/10.1371/journal.pone.0269440

Influence of Consumption of a High-Protein vs. High-Carbohydrate Meal on the Physiological Cortisol and Psychological Mood Response in Men and Women | PLOS One. https://doi.org/10.1371/journal.pone.0016826

Lemmens, S. G., Born, J. M., Martens, E. A., Martens, M. J., & Westerterp-Plantenga, M. S. (2011a). Influence of Consumption of a High-Protein vs. High-Carbohydrate Meal on the Physiological Cortisol and Psychological Mood Response in Men and Women. PLOS ONE, 6(2), e16826. https://doi.org/10.1371/journal.pone.0016826

Lemmens, S. G., Born, J. M., Martens, E. A., Martens, M. J., & Westerterp-Plantenga, M. S. (2011b). Influence of Consumption of a High-Protein vs. High-Carbohydrate Meal on the Physiological Cortisol and Psychological Mood Response in Men and Women. PLOS ONE, 6(2), e16826. https://doi.org/10.1371/journal.pone.0016826

Macvanin, M. T., Gluvic, Z., Zafirovic, S., Gao, X., Essack, M., & Isenovic, E. R. (2023). The protective role of nutritional antioxidants against oxidative stress in thyroid disorders. Frontiers in Endocrinology, 13. https://doi.org/10.3389/fendo.2022.1092837

Markus, C. R., Panhuysen, G., Tuiten, A., Koppeschaar, H., Fekkes, D., & Peters, M. L. (1998). Does carbohydrate-rich, protein-poor food prevent a deterioration of mood and cognitive performance of stress-prone subjects when subjected to a stressful task? Appetite, 31(1), 49–65. https://doi.org/10.1006/appe.1997.0155

Partsalaki, I., Markantes, G. K., & Michalaki, M. A. (2024). Low-Glycemic Load Diets and Thyroid Function: A Narrative Review and Future Perspectives. Nutrients, 16(3), 347. https://doi.org/10.3390/nu16030347

Reinehr, T., de Sousa, G., & Andler, W. (2006). Hyperthyrotropinemia in Obese Children Is Reversible after Weight Loss and Is Not Related to Lipids. The Journal of Clinical Endocrinology & Metabolism, 91(8), 3088–3091. https://doi.org/10.1210/jc.2006-0095

Reiter, R. J., Rosales-Corral, S., Tan, D. X., Jou, M. J., Galano, A., & Xu, B. (2017). Melatonin as a mitochondria-targeted antioxidant: One of evolution’s best ideas. Cellular and Molecular Life Sciences: CMLS, 74(21), 3863–3881. https://doi.org/10.1007/s00018-017-2609-7

Sejbuk, M., Mirończuk-Chodakowska, I., & Witkowska, A. M. (2022). Sleep Quality: A Narrative Review on Nutrition, Stimulants, and Physical Activity as Important Factors. Nutrients, 14(9), 1912. https://doi.org/10.3390/nu14091912

Shulhai, A.-M., Rotondo, R., Petraroli, M., Patianna, V., Predieri, B., Iughetti, L., Esposito, S., & Street, M. E. (2024). The Role of Nutrition on Thyroid Function. Nutrients, 16(15), 2496. https://doi.org/10.3390/nu16152496

Stępniak, J., & Karbownik-Lewińska, M. (2024). Protective Effects of Melatonin against Carcinogen-Induced Oxidative Damage in the Thyroid. Cancers, 16(9), 1646. https://doi.org/10.3390/cancers16091646

Takeda, E., Terao, J., Nakaya, Y., Miyamoto, K., Baba, Y., Chuman, H., Kaji, R., Ohmori, T., & Rokutan, K. (2004). Stress control and human nutrition. The Journal of Medical Investigation, 51(3,4), 139–145. https://doi.org/10.2152/jmi.51.139

Tang, J., Krushelnycky, L., Shaqo, A., & Cho, C. E. (2025). A Comprehensive Review of Nutritional Influences on the Serotonergic System. Advances in Nutrition, 16(11), 100524. https://doi.org/10.1016/j.advnut.2025.100524

Venditti, P., & Di Meo, S. (2006). Thyroid hormone-induced oxidative stress. Cellular and Molecular Life Sciences: CMLS, 63(4), 414–434. https://doi.org/10.1007/s00018-005-5457-9

Vranjić, P., Vuković, M., Blažetić, S., & Viljetić, B. (2025). Ketogenic Diet and Thyroid Function: A Delicate Metabolic Balancing Act. Current Issues in Molecular Biology, 47(9), 696. https://doi.org/10.3390/cimb47090696

Wurtman, R. J., & Wurtman, J. J. (1988). Do carbohydrates affect food intake via neurotransmitter activity? Appetite, 11 Suppl 1, 42–47.