Feeling cold when others around you seem comfortable usually comes down to how efficiently your body produces and distributes heat. That process depends on your metabolism, your circulation, your body composition, and even how well you slept last night. Some causes are straightforward lifestyle factors you can address on your own, while others point to medical conditions worth investigating.
How Your Body Makes and Keeps Heat
Your body generates heat primarily through your baseline metabolism, the constant burn of energy that keeps your organs running. When the surrounding temperature drops below roughly 23°C (73°F), your body kicks in additional heat sources: your muscles begin low-level contractions (shivering), and specialized fat tissue burns fatty acids specifically to produce warmth. Thyroid hormones orchestrate much of this process, controlling how fast your cells convert food into energy. When any part of this system underperforms, you feel cold before everyone else does.
Thyroid Problems Are a Leading Cause
An underactive thyroid is one of the most common medical reasons for cold intolerance. Thyroid hormones regulate your metabolic rate, which directly controls how much heat your body generates at rest. When levels are low, your internal furnace essentially turns down.
Even people already being treated for hypothyroidism can still run cold. A study in the Journal of the Endocrine Society found that patients on standard thyroid medication had significantly lower palm temperatures than healthy controls (32.1°C vs. 33.1°C) and a reduced ability to convert inactive thyroid hormone into its active form. This suggests their bodies struggle to ramp up heat production in response to environmental changes, even when blood tests look acceptable. If you’re on thyroid medication and still feel persistently cold, it may be worth discussing your conversion ratio with your doctor rather than just looking at standard lab numbers.
Iron and B12 Deficiency
Your red blood cells carry oxygen to tissues, and that oxygen fuels the metabolic reactions that generate heat. When you’re low on iron, you produce fewer functional red blood cells, which means less oxygen reaches your muscles and organs. The result is a measurable drop in metabolic rate and heat production. Research from the National Academies of Sciences has shown that restoring red blood cell levels in iron-deficient individuals reverses the thermoregulatory problems, preventing the drops in core temperature seen during cold exposure.
Vitamin B12 deficiency works through the same pathway. Without enough B12, your body can’t manufacture healthy red blood cells efficiently, leading to a form of anemia that leaves you shivering and cold, particularly in your hands and feet. Vegetarians, vegans, older adults, and people with digestive conditions that impair nutrient absorption are at higher risk for both deficiencies.
Body Composition Matters More Than You’d Think
Both muscle and fat play distinct roles in keeping you warm, and having less of either can leave you more sensitive to cold.
Subcutaneous fat acts as insulation. People with higher body fat lose less heat to the environment, maintain higher skin temperatures, and shiver less during cold exposure. This is why very lean individuals often feel cold more easily. Fat has strong insulative properties, and a thinner layer simply lets heat escape faster.
Muscle, on the other hand, is your body’s primary heat generator. Skeletal muscle has nearly twice the heat-holding capacity of fat tissue (3.7 vs. 2.0 kJ per kilogram per degree). People with higher muscle mass can tolerate lower temperatures while keeping their core temperature stable. If you’ve lost muscle due to aging, illness, or inactivity, your body produces less heat at baseline and has less capacity to generate warmth when temperatures drop.
Circulation Problems and Raynaud’s
Sometimes the issue isn’t heat production but heat delivery. Your blood carries warmth from your core to your extremities, and anything that restricts blood flow to your fingers, toes, ears, or nose will make those areas feel painfully cold.
Raynaud’s phenomenon is a condition where blood vessels in the extremities narrow dramatically in response to cold temperatures or emotional stress. During an attack, affected fingers or toes may turn white or blue and feel numb or painful. Episodes can last anywhere from a few minutes to a few hours. Most cases are mild and manageable with warm gloves and avoiding triggers, but severe Raynaud’s can cause small painful sores at the fingertips. The condition is more common in women and in people living in colder climates.
Poor circulation from other causes, including diabetes, peripheral artery disease, or simply sitting still for long periods, can produce similar cold sensations in the hands and feet without the dramatic color changes of Raynaud’s.
Medications That Make You Cold
Certain medications reduce blood flow to your extremities as a side effect. Beta blockers, commonly prescribed for high blood pressure, heart conditions, and anxiety, are a well-known culprit. Non-selective types in particular cause cold hands and feet by blocking the signals that normally keep blood vessels in your extremities open. This side effect is more pronounced in older adults. If you started feeling cold around the same time you began a new medication, the timing may not be coincidental.
Dehydration and Blood Volume
Water makes up a large portion of your blood volume, and even mild dehydration reduces it. When blood volume drops, your body faces a tradeoff: it can send blood to your skin to regulate temperature, or it can keep blood centralized to support your organs, but doing both becomes difficult. The result is reduced blood flow to your skin and extremities, which makes you feel colder. Dehydration also makes your blood more concentrated, which further impairs the body’s ability to distribute heat evenly. Most people don’t connect feeling cold with not drinking enough water, but the link is direct and well-established.
Sleep Deprivation Disrupts Temperature Control
The same neurons in your brain that regulate sleep also control your body temperature. This isn’t a coincidence. These two systems are deeply intertwined, and disrupting one throws off the other. Research at Washington University in St. Louis confirmed that sleep loss alters temperature preferences and impairs the body’s thermoregulatory responses. When you’re sleep-deprived, your body’s ability to maintain a stable internal temperature weakens, which can leave you feeling cold at times when you normally wouldn’t. Chronic sleep disruption, including the kind caused by inconsistent sleep schedules, produces similar effects.
When Cold Sensitivity Signals Something Bigger
Occasional cold sensitivity on a chilly day is normal. Persistent cold intolerance, especially when paired with other symptoms, often points to something identifiable. Hypothyroidism typically comes with fatigue, weight gain, dry skin, and constipation alongside cold intolerance. Iron deficiency often shows up with pale skin, brittle nails, unusual fatigue, and shortness of breath during activity. B12 deficiency can cause tingling or numbness in the hands and feet, balance problems, and brain fog.
If you’re consistently colder than the people around you and it’s a change from your baseline, a simple blood panel checking thyroid function, iron levels, and B12 can rule out or confirm the most common medical causes. Many of these conditions are straightforward to treat once identified, and the cold sensitivity often resolves along with the underlying problem.