Why am I always cold?
Thyroid, iron and
the nutrients that keep you warm.
If you reach for a sweater when everyone else is comfortable, your body may be making or holding heat less well than it could. The two most common medical reasons are an underactive thyroid and low iron, and both show up on simple blood tests. Here’s how your body makes heat, the nutrients involved, the everyday causes, what to eat, and what to ask your doctor.
Why am I always cold? The short answer
Why am I always cold when others are not?
Feeling cold all the time usually means your body is making less heat or losing it faster. The two most common medical causes are an underactive thyroid and low iron. Low vitamin B12, low body weight, eating too little, sitting still and strong air-conditioning also play a part. A doctor can check with four blood tests: TSH, haemoglobin, ferritin and vitamin B12.
Feeling cold when others are comfortable is common, and most of the time the cause is simple and fixable. This guide walks through each cause in turn, starting with how your body keeps itself warm in the first place.
How your body makes heat
How does the body make heat?
Your body makes heat by burning food with oxygen in every cell. Thyroid hormone sets how fast that burning happens. Iron carries the oxygen. Muscles and body fat help make and hold the heat. A shortfall in any of these can leave you feeling cold.
Think of your body as a house with a heater. Three things keep the house warm:
- The thermostat: your thyroid. Thyroid hormones tell every cell how fast to burn fuel. Turn them down, and the whole house cools.
- The air supply: iron. Iron in your red blood cells carries oxygen to the cells. A fire with less air burns low.
- The fuel and the walls: food, muscle and body fat. Food is the fuel, working muscles make heat, and body fat holds it in.
Several nutrients keep these parts working, which is why this page looks well beyond any single vitamin.
The thyroid: your body’s thermostat
Does thyroid cause feeling cold?
Yes. An underactive thyroid (hypothyroidism) is the best-known medical cause of feeling cold. In a study of eight Indian cities, about 11% of adults had it, women about three times as often as men, and roughly a third did not know. A TSH blood test finds it, and treatment is a daily tablet prescribed by a doctor.
Your thyroid is a small gland in the front of your neck. When it makes too little hormone, the body slows down. The common signs are trouble tolerating cold, tiredness, weight gain, dry skin, thinning hair, constipation and a slow heartbeat.1
It is common in India. In a study of about 5,360 adults in eight cities, about 11% had an underactive thyroid. Women were affected about three times as often as men, and around a third of those affected had not been diagnosed.2
The good news is that it is easy to find and well treated. A blood test called TSH picks it up, and a doctor treats it with a daily thyroid hormone tablet.1
Iron: the oxygen carrier, and the thyroid’s helper
Can low iron make you feel cold?
Yes. Iron helps keep you warm in two ways. It carries the oxygen your cells need to make heat, and the body needs it to make thyroid hormone. In cold-room studies, women with low iron lost body heat faster, and held it better after their iron was restored. A ferritin blood test shows your iron stores.
The US National Institutes of Health lists poor body-temperature control among the effects of iron deficiency.3 The research behind that is striking:
- Scientists placed women with low iron in cool air and cool water. They lost body heat faster than women with normal iron, and their thyroid hormone response was weaker.4
- After iron was restored, they held their body temperature better.4
- The same effect was seen in women whose iron stores were low but who were not yet anaemic.4
Iron also helps the thyroid. The enzyme that builds thyroid hormone contains iron. In a study of 3,846 adults in Spain, people with low iron stores (ferritin under 30) were about 1.5 to 1.8 times as likely to have low thyroid hormone levels.5
Low iron is very common in India: 57% of women aged 15 to 49 are anaemic,6 and people on vegetarian diets need about 1.8 times as much iron as meat-eaters because plant iron is absorbed less well.3 A woman needs 29 mg a day and a man 19 mg.7
“Iron carries the oxygen your cells burn for heat, and it helps build the thyroid hormone that sets the pace. Two jobs, one mineral.”
Why iron matters for warmth
Ask for ferritin, not only haemoglobin. Ferritin measures your iron stores, which run down before haemoglobin falls. A ferritin below 30 suggests iron deficiency.3 Iron tablets work well, and your doctor can set the right dose from your result.
The thyroid’s mineral team: iodine, selenium, zinc and copper
Which minerals does the thyroid need?
The thyroid needs several minerals. Iodine is the building block of thyroid hormone. Selenium helps change the hormone into its active form. Zinc and copper support thyroid hormone levels and iron use. Most people get enough iodine from iodised salt, and enough selenium and zinc from a mixed diet.
| Mineral | Its job | Daily need (adults) | Good sources |
|---|---|---|---|
| Iodine | Building block of thyroid hormones T4 and T3 | 150 mcg | Iodised salt, fish, eggs, milk |
| Selenium | Helps turn T4 into active T3 | 55 mcg | Fish, eggs, Brazil nuts, whole grains |
| Iron | Carries oxygen; needed to make thyroid hormone | 29 mg women, 19 mg men | Dals, chana, rajma, green leafy vegetables, sesame, eggs, meat |
| Zinc | Supports normal thyroid hormone levels | 13 mg women, 17 mg men | Dals, nuts, seeds, whole grains, meat |
| Copper | Helps the body move and use iron | Small amounts | Nuts, seeds, dals, whole grains |
Iodine. Thyroid hormone is built from iodine, and iodine has an approved claim for normal thyroid function.8,9 India’s iodised salt programme is a public-health success: in the national iodine survey, 76% of households used properly iodised salt.10 If you use rock salt, pink salt or sea salt that is not iodised, you may be getting much less.
Selenium. The thyroid holds more selenium than any other organ. Selenium-based enzymes change T4, the storage form of thyroid hormone, into T3, the active form. Selenium also has an approved claim for normal thyroid function.11,9
Zinc and copper. In carefully controlled diet studies, people fed too little zinc showed a fall in thyroid hormone similar to that seen with low iron. Severe copper deficiency has been linked with low body temperature, and copper helps the body transport iron.4,9
Vitamin B12 and folate
Can low vitamin B12 make you feel cold?
It can, through anaemia. Vitamin B12 and folate are needed to make red blood cells. When either is low, the body makes fewer healthy red cells, a type of anaemia. Any anaemia can leave you tired and pale with cold hands and feet. Low B12 is common in vegetarians and is easy to test for.
Iron is not the only nutrient your blood needs. Vitamin B12 and folate are both needed to build red blood cells. Too little of either causes a different kind of anaemia, and any anaemia can bring cold hands and feet along with tiredness and pale skin.12 Low B12 can also cause pins and needles in the hands and feet. Our guides to vitamin B12 deficiency in India and tingling hands and feet go deeper.
Everyday reasons for feeling cold
What are the everyday reasons for always feeling cold?
Many people feel cold for everyday reasons: strong office air-conditioning, low body weight, eating too little, sitting still for long hours, poor sleep, or fingers and toes that react strongly to cold (Raynaud’s). Women often feel colder than men in the same room because office temperatures were designed around men’s body heat.
Office air-conditioning
Indoor temperature standards were built around a man’s body heat and can overestimate a woman’s by up to 35%. Feeling cold at your desk is often the room, not you.13
Low body weight or eating too little
Less body fat holds less heat, and a very low-calorie diet gives the body less fuel to burn.
Sitting still
Working muscles make heat. Long hours without moving let you cool down. A brisk five-minute walk helps.
Raynaud’s
Fingers and toes that turn white or blue in the cold, then red as they warm. It is common and usually harmless; keeping warm and regular exercise help.14
Where does vitamin D fit? Vitamin D is one of the most common gaps in India and matters for bones, muscles and immunity. Feeling cold is not one of its known signs, so it is not the first place to look for this symptom. Our vitamin D guide covers what it does do.
What to eat if you always feel cold
What should I eat if I always feel cold?
Eat enough: regular meals with enough calories and protein give your body fuel to burn. Include iron-rich foods such as dals, chana, rajma, green leafy vegetables and sesame, with lemon, amla or another vitamin C source, and keep tea and coffee away from meals. Use iodised salt, and include milk, curd or eggs for B12. Warm meals feel good, but no single food heats you up for long.
Food is the fuel for your body’s heater, and some nutrients help it burn. Five simple habits cover most of it:
- Don’t under-eat. Skipped meals and very low-calorie diets leave the body less fuel, and it turns the heat down to save energy.
- Protein at every meal. Dal, paneer, curd, eggs or soya. Protein keeps muscle, and muscle makes heat.
- Iron with vitamin C. Pair dals, chana, rajma, greens and sesame with lemon, amla, guava or tomato, which help your body absorb plant iron.3
- Tea and coffee between meals, not with them. They reduce how much plant iron you absorb.3
- Iodised salt and a B12 source. Iodised salt supports the thyroid, and milk, curd or eggs supply B12 on a vegetarian diet.8
What to do: the tests to ask your doctor about
Which blood tests should I ask for if I am always cold?
If you feel cold most of the time, ask your doctor about four blood tests: TSH for the thyroid, haemoglobin for anaemia, ferritin for iron stores, and vitamin B12. See a doctor sooner if feeling cold comes with tiredness, weight change, hair thinning, constipation, heavy periods, or fingers that change colour.
- Rule out the roomNotice whether you feel cold everywhere, or mainly in air-conditioned places. Keep a layer handy and move every hour.
- Ask about a TSH testTSH is the first test for an underactive thyroid. Your doctor may add free T4.
- Ask for haemoglobin and ferritin togetherHaemoglobin shows anaemia. Ferritin shows iron stores, which fall first.
- Add vitamin B12 if you are vegetarianLow B12 is common on vegetarian diets and is easy to check.
- Eat for warmthUse iodised salt, and include iron-rich dals and greens with a source of vitamin C such as lemon, plus enough protein and calories.
- Treat what the tests showTake iron, thyroid tablets or B12 as your doctor prescribes, and recheck when advised.
See a doctor soon if feeling cold is new, getting worse, or comes with marked tiredness, unexplained weight change, hair thinning, constipation, very heavy periods, breathlessness, or fingers or toes that change colour or hurt.
Test first. Then give your body what it is missing.
Thyroid and iron problems need a doctor and a blood test. Alongside that, everyday energy depends on getting enough of the basics, and magnesium is one of the most commonly missed. Magnesium contributes to normal energy-yielding metabolism and normal muscle function.
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Join the waitlist →Nutrient Gap Finder
Answer a few quick questions about your food, routine and symptoms to see which nutrients you may be running low on, and which tests to ask your doctor about.
Try the Nutrient Gap Finder →- The iron and cold studies were small laboratory experiments, mostly in women with iron-deficiency anaemia, at 16°C air and 28°C water; they show the mechanism clearly but not how often low iron explains everyday chilliness.4
- The Spanish study looked at people at one point in time, so it shows a link between low ferritin and lower thyroid hormone, not proof of cause; TSH did not differ.5
- The zinc findings come from small, tightly controlled diet studies, and the copper findings mainly from animals and rare severe deficiency.4
- More iodine or selenium is not better. Too much iodine can itself disturb the thyroid (upper level 1,100 mcg a day), and too much selenium causes hair and nail loss (upper level 400 mcg). People with thyroid disease should ask their doctor before taking either.8,11
- Iron should be taken at a dose guided by a blood test; iron, calcium and magnesium supplements should be kept about four hours from thyroid tablets.1
- The office-temperature study measured 16 young women doing light office work.13
- The eight-city thyroid figure comes from urban adults and may not reflect rural India.2
- Iron stores take time to rebuild: doctors usually recheck ferritin after about three months of treatment, though many people feel better sooner.3
- European approved claims describe what a nutrient does at adequate intakes; they are not claims to treat any illness.9
Feeling cold, answered plainly.
Why am I always cold when others are not?
Which deficiency makes you feel cold?
Can low iron make you feel cold?
Can I be low in iron if my haemoglobin is normal?
Does thyroid cause feeling cold?
How common is thyroid disease in India?
Which blood tests should I ask for if I am always cold?
Why are my hands and feet always cold?
Why do women feel colder than men?
Does vitamin D deficiency make you feel cold?
Do I need iodine or selenium supplements for my thyroid?
Can I take magnesium if I am on thyroid tablets?
Why am I always cold and tired?
Why am I always cold even in summer?
What should I eat if I always feel cold?
Which Indian foods are high in iron?
How long does it take for iron to stop me feeling cold?
Can stress make you feel cold?
Can lack of sleep make you feel cold?
Can low blood pressure make you feel cold?
Is always feeling cold a sign of diabetes?
Does magnesium help you feel warm?
Studies behind this guide
- National Institute of Diabetes and Digestive and Kidney Diseases (NIH). Hypothyroidism (underactive thyroid). niddk.nih.gov
- Unnikrishnan AG, Kalra S, Sahay RK, Bantwal G, John M, Tewari N. Prevalence of hypothyroidism in adults: an epidemiological study in eight cities of India. Indian J Endocrinol Metab. 2013;17(4):647–652. PMID 23961480
- National Institutes of Health, Office of Dietary Supplements. Iron: Fact Sheet for Health Professionals. ods.od.nih.gov
- Beard JL. Micronutrient deficiency states and thermoregulation in the cold. In: Nutritional Needs in Cold and High-Altitude Environments. Washington, DC: National Academies Press; 1996. nationalacademies.org
- Maldonado-Araque C, Valdes S, Lago-Sampedro A, et al. Iron deficiency is associated with hypothyroxinemia and hypotriiodothyroninemia in the Spanish general adult population: Di@bet.es study. Sci Rep. 2018;8:6571. doi:10.1038/s41598-018-24352-9
- International Institute for Population Sciences (IIPS) and ICF. National Family Health Survey (NFHS-5), 2019–21: India. Mumbai: IIPS; 2021.
- ICMR-National Institute of Nutrition. Nutrient Requirements for Indians: Recommended Dietary Allowances and Estimated Average Requirements, 2020. nin.res.in
- National Institutes of Health, Office of Dietary Supplements. Iodine: Fact Sheet for Health Professionals. ods.od.nih.gov
- Commission Regulation (EU) No 432/2012: list of permitted health claims made on foods — iodine, selenium, iron, copper and magnesium entries.
- Nutrition International, ICCIDD, AIIMS and Kantar. India Iodine Survey 2018–19: national report. nutritionintl.org
- National Institutes of Health, Office of Dietary Supplements. Selenium: Fact Sheet for Health Professionals. ods.od.nih.gov
- National Heart, Lung, and Blood Institute (NIH). Anemia: symptoms. nhlbi.nih.gov
- Kingma B, van Marken Lichtenbelt W. Energy consumption in buildings and female thermal demand. Nat Clim Chang. 2015;5:1054–1056.
- NHS. Raynaud’s. nhs.uk