Feeling cold all the time while also struggling with persistent fatigue often points to treatable problems like anemia, iron or B12 deficiency, or hypothyroidism — conditions that slow oxygen delivery, nerve function, or metabolism. Other contributors include poor circulation, Raynaud’s, low body weight, chronic illness, not enough sleep, and some medications. Basic tests such as CBC, ferritin, B12, TSH and a vascular or neurologic check usually clarify the cause and help plan next steps.
Key Takeaways
Common medical reasons include anemia, hypothyroidism, and vitamin B12 deficiency — each can lower energy and the body’s heat production.
Poor circulation (for example, peripheral artery disease or Raynaud’s) and autonomic or peripheral neuropathy can make your hands and feet feel chronically cold.
Lifestyle factors — poor sleep, low body weight, inactivity, anxiety, and a cold environment — reduce metabolic heat and increase tiredness.
Useful tests: CBC with ferritin, B12, TSH and free T4. These results help guide diagnosis and treatment.
Practical measures: layer clothing, stay hydrated, choose warm, calorie‑rich meals, move regularly to boost circulation, and see your clinician if symptoms don’t improve.
Common Medical Causes of Feeling Cold and Fatigued
Why do coldness and tiredness often come together? Medical causes explain this link. Anemia, especially from iron deficiency, reduces the blood’s ability to carry oxygen, which causes fatigue and cool extremities. Vitamin B12 deficiency also affects red blood cell production and nerve health, leading to weakness, numbness and increased sensitivity to cold. Hypothyroidism slows metabolism and the body’s temperature control, so you may feel persistently tired and chilly. Poor circulation from vascular disease or Raynaud’s phenomenon limits blood flow to the hands and feet, making them feel cold and adding to fatigue. Low body fat and chronic illnesses can worsen these symptoms. Simple bloodwork, thyroid panels, and vascular checks help pinpoint the cause; targeted treatment typically improves both warmth and energy.
Lifestyle and Environmental Factors That Drain Energy and Warmth
Everyday habits and surroundings can sap both warmth and energy. Things like sleep deprivation, low BMI, anxiety, inactivity and anemia reduce heat production and stamina. Not getting enough sleep disrupts thermoregulation and metabolism; having a low BMI means less natural insulation. Anxiety diverts blood to the core and cools the hands and feet; aging or a sedentary lifestyle impairs circulation. Iron or B12 deficiency lowers oxygen delivery and causes fatigue plus cold intolerance. Cold environments, dehydration, and stuffy indoor air make symptoms worse. Often, simple checks and lifestyle changes help — but persistent or worsening symptoms should be evaluated by a clinician.
Factor | Effect on Warmth | Effect on Energy |
Sleep deprivation | Disrupts temperature control | Makes you less alert and more tired |
Low BMI | Less natural insulation | Fewer energy reserves |
Anxiety / poor circulation / anemia | Hands and feet feel colder | Fatigue from lower oxygen delivery |
How to Tell If a Nutrient Deficiency or Thyroid Problem Is to Blame
If unexplained chilliness and fatigue continue, the symptom pattern and a few simple tests usually separate nutrient deficiencies from thyroid disease. Vitamin B12 deficiency commonly causes tiredness, numbness and cold sensitivity because low B12 affects red blood cells and nerves. Iron deficiency anemia reduces oxygen transport, leading to tiredness and cold intolerance. Hypothyroidism slows metabolic rate and heat production, often with persistent lethargy, weight changes and slower thinking. Initial testing typically includes CBC, serum ferritin, B12 level, and thyroid function tests (TSH, free T4). Improvement after iron or B12 replacement or thyroid hormone confirms the diagnosis; clinicians also evaluate medication effects, absorption issues and the need for follow-up testing.
When Circulation or Nervous System Issues Make You Cold
Could poor circulation or nervous system dysfunction explain why your hands and feet stay cold? The body must deliver warm blood to the extremities for normal temperature perception. Reduced blood flow or disrupted nerve control can cause ongoing cold extremities.
Peripheral artery disease or arterial narrowing limits blood flow to fingers and toes, causing persistent coolness.
Raynaud’s phenomenon causes exaggerated vasospasm that intermittently cuts off circulation and leaves digits numb and cold.
Aging, low blood pressure, some medications, or pregnancy-related changes can reduce blood flow to the extremities.
Autonomic or peripheral nerve dysfunction interferes with temperature regulation and sensation, so you may feel cold even when core temperature is normal.
A clinician can help distinguish vascular from neurologic causes and recommend the right tests.
Practical Steps to Boost Energy and Stay Warmer
While you and your clinician investigate underlying causes, these practical steps can raise core temperature and energy. Dress in layers — including warm base layers, sweaters and wind‑resistant outerwear — and wear a hat or scarf to limit heat loss. Choose warm, nonalcoholic drinks and soups to add calories and immediate warmth. Gentle, regular activity improves circulation; quitting smoking also helps blood flow. If signs point to anemia or hypothyroidism, get a medical evaluation; blood tests and appropriate iron, B12 or thyroid treatment can restore energy and temperature control. Stay hydrated and aim for a healthy weight for better insulation. Seek prompt care if coldness continues or comes with severe fatigue, tingling, weakness or shortness of breath.
Frequently Asked Questions
Why Do I Feel so Tired and Cold All the Time?
Common causes include anemia, thyroid problems, poor sleep, low body fat or circulation issues. These reduce metabolism, oxygen delivery or insulation. Basic bloodwork and a clinical exam usually identify treatable causes and guide care.
What Is My Body Lacking if I Am Always Cold?
You might be low in iron or vitamin B12, have low thyroid hormone, be undernourished or underweight, dehydrated, or have impaired circulation. Any of these can cut heat production or delivery and cause ongoing cold and fatigue.
What Deficiency Makes You Cold and Tired?
Iron deficiency and vitamin B12 deficiency commonly cause both cold sensitivity and fatigue because they affect red blood cell function and energy production. Thyroid problems can produce similar symptoms and should be checked.
Is Being Cold a Symptom of Diabetes?
Yes. Diabetes can cause persistent coldness through poor circulation, neuropathy or kidney problems and from poorly controlled blood sugar. Other signs include numbness, fatigue and slow wound healing — talk to your clinician about glucose control and evaluation.
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Sources
Zamwar, U. and Muneshwar, K. (2023). Epidemiology, Types, Causes, Clinical Presentation, Diagnosis, and Treatment of Hypothyroidism. Cureus. https://www.cureus.com/articles/175208-epidemiology-types-causes-clinical-presentation-diagnosis-and-treatment-of-hypothyroidism#!/
Rissardo, J., Rahim, F., Dway, A., Elhassan, W., Elbadawi, M., Sayad, R., … & Caprara, A. (2025). Exploring Fatigue in Parkinson’s Disease: A Comprehensive Literature Review.. https://www.preprints.org/manuscript/202501.2084
Cojocaru, C. and Alin, B. (2023). The current assessment and management of thyroid nodules. Moldovan Journal of Health Sciences, 10(1), 73-81. https://mjhs.md/article/current-assessment-and-management-thyroid-nodules
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