Why Am I So Cold All The Time?

Why Am I So Cold All The Time? This is one of the most common questions I get asked in clinical practice. Feeling cold “for no reason” can be frustrating—whether it’s icy fingers in a perfectly warm room or shivering while everyone else is fine. The good news: in most cases, there is a reason, and many are addressable. Below I’ll walk you through how temperature regulation works, the most common medical explanations for persistent chilliness, and practical, evidence-grounded steps to feel warmer.

How your body normally stays warm

Your brain (especially the hypothalamus) coordinates a symphony of heat-saving and heat-making tricks: constricting blood vessels in your skin to reduce heat loss, triggering muscle shivering, and dialling up “non-shivering thermogenesis” in special fat called brown adipose tissue (BAT). BAT burns fuel to generate heat, and repeated mild cold exposure can increase its activity, improving comfort in the cold. In controlled studies, just 7–10 days of daily mild cold boosted non-shivering thermogenesis and BAT activity in adults—and people felt more comfortable afterwards (source, source).

Thyroid hormones fine-tune this system (source, source). They help set basal metabolic rate and make BAT more responsive to nerves that turn it on. When thyroid hormone levels are low, heat production falls; when normal, thermoregulation is smoother.

When “always cold” deserves attention

Everyone’s tolerance for cold varies, but if you’re persistently colder than peers in the same environment, or you’ve developed new cold sensitivity, it’s reasonable to look for medical contributors. The list below covers the most common, evidence-backed culprits.

Iron deficiency (with or without anaemia)

Iron carries oxygen in haemoglobin and also supports cellular energy production. Low iron is linked to cold intolerance—and correcting iron often helps. Low iron status correlates with reduced thermoregulation and higher cold sensitivity (source, source); iron repletion improved cold symptoms in several trials. If menstruation is heavy, pregnancy/postpartum, or diet is low in iron, this jumps high on the list.

What to ask your clinician about: haemoglobin and ferritin (your iron store). If low, food sources (e.g., red meat) and/or supplementation can be considered.

My go to iron supplement is: Iron-C.

Copper Deficiency and Feeling Cold

Copper might not be the first mineral you think of, but it plays a surprisingly big role in keeping your body warm (source). The mineral is essential for making certain enzymes that help with energy production, iron metabolism, and healthy blood cells.

When copper levels are too low, it can lead to anemia (low red blood cells), nerve problems, heart stress, and even issues with connective tissues. One of the earliest reports of copper deficiency in humans noted hypothermia (low body temperature) as a symptom.

Animal studies back this up—copper-deficient animals often have lower body temperatures and reduced thyroid hormone levels, both of which affect heat production and energy balance. Since copper is linked to iron metabolism, sometimes the effects overlap with iron deficiency, which also makes people feel cold.

In short, if your copper levels are low, your body may struggle to produce enough thyroid hormones and red blood cells—both critical for regulating warmth.

My recommended product is Zinc & Copper which provides an healthy ratio of zinc and copper (high zinc can cause a copper deficiency).

Zinc Deficiency and Poor Thermoregulation

Zinc is another key mineral tied to feeling cold. It’s involved in hundreds of cellular processes, including energy metabolism, protein synthesis, and thyroid function. Without enough zinc, the body can’t regulate temperature efficiently (source).

In research studies, zinc-deficient animals often showed hypothermia (low body temperature) and difficulty maintaining warmth in cold environments. Humans with zinc deficiency have also been shown to experience a drop in thyroid hormone levels (particularly T4), which slows down metabolism and makes it harder to stay warm.

Because thyroid hormones (T3 and T4) are the body’s “internal thermostat,” low zinc can contribute to fatigue, sluggishness, and feeling unusually cold—even when others around you are comfortable.

Thyroid Under-Activity (hypothyroidism)

Hypothyroidism classically causes fatigue, dry skin, weight changes—and cold intolerance. Mechanistically, low thyroid hormones reduce heat production and limit BAT activity; restoring thyroid levels improves thermogenic responses. Reviews in endocrinology outline this thyroid–BAT partnership and its central role in temperature control.

What to ask about: a thyroid test that includes TSH, T4, T3, reverse T3, and thyroid antibodies.

Raynaud’s phenomenon (over-reactive blood vessels)

If your fingers or toes go white/blue, tingle, or hurt with cold or stress—then flush red on rewarming—you may have Raynaud’s, where small arteries constrict too strongly. It can occur on its own or with autoimmune conditions, prior cold injury, or certain drugs (source); careful history helps tell those apart.

Thyroid imbalances are also associated with raynauds (source). You can see how so much of this is interconnected.

What helps: keeping the whole body warm (not just hands), avoiding cold exposure.

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Body composition and energy balance

Heat is mass-dependent. People with lower body mass or less peripheral insulation lose heat faster, especially from the hands. Population and lab studies show lower BMI is associated with greater reported cold sensitivity; hand heat loss during severe cold exposure also correlates with body size and fat. Conversely, obesity provides insulation but does not guarantee comfort; obese adults often have reduced capacity to ramp up cold-induced thermogenesis despite insulation.

A sustained calorie deficit (hard training, illness, dieting) can also leave you chilly because there’s simply less fuel available to burn for heat; experimental work in soldiers demonstrated markedly worse cold tolerance after prolonged negative energy balance.

Age and sex hormone influences

Thermal control changes with age—older adults rely more on vasoconstriction but that response is blunted, which can increase cold vulnerability.

Estrogen and progesterone also modulate autonomic temperature control and skin blood flow (source). Estrogens generally enhance heat dissipation (lower set point), while progesterone raises it; shifts across the menstrual cycle, with contraceptives, and at menopause narrow or shift the “thermoneutral zone,” altering sensations of heat and cold. While most popular discussion focuses on hot flashes, day-to-day thermal sensitivity can change too.

Mitochondria: Your Internal Heat Generators

If you’re constantly asking “Why am I so cold all the time?”, one surprising place to look is your mitochondria. Often called the “powerhouses of the cell,” mitochondria generate the energy (ATP) that fuels every bodily process. But beyond energy, they play a crucial role in thermogenesis—your body’s ability to create heat and maintain a stable temperature (source).

How Mitochondria Regulate Body Temperature

Inside specialised fat cells known as brown adipose tissue (BAT), mitochondria contain a protein called uncoupling protein 1 (UCP1). Instead of making ATP, UCP1 allows mitochondria to release energy as heat, a process essential for warming the body in cold conditions. Even beige fat cells, which can “convert” into heat-generating cells, depend on mitochondrial health for this function.

Studies show that when mitochondrial function is impaired, brown fat loses its thermogenic ability, leading to feeling colder and difficulty adapting to temperature changes.

Causes of Mitochondrial Dysfunction

Several factors can disrupt mitochondria and reduce heat production:

• Aging: Thermogenic function of BAT naturally declines over time, but drugs like metformin may slow this decline .

• Metabolic stress: High-fat diets, obesity, and elevated uric acid inhibit mitochondrial thermogenesis.

• Drugs: Some antiretrovirals disrupt UCP1 and suppress heat production.

• Inflammation and oxidative stress: Chronic inflammation alters mitochondrial signalling, reducing their efficiency.

• Nutrient deficiencies. Numerous nutrients including B vitamins, CoQ10, zinc are important for mitochondrial function.

• Lack of exercise and/or sleep.

• Toxins: certain heavy metals and mycotoxins can disrupt mitochondrial function.

Supporting Healthy Mitochondria for Warmth

Fortunately, research suggests multiple ways to keep your mitochondria working well:

• Regular exercise enhances mitochondrial biogenesis and heat production capacity.

• Nutritional support: B vitamins, vitamin C, zinc, selenium, vitamin E, glutathione, carnitine – there are may nutrients required for optimal mitochondrial function. Mitochondrial NRG is a great product that provides several key nutrients.

• Cold exposure training: Mild cold exposure naturally activates brown fat mitochondria, strengthening thermogenic responses.

• Metabolic health maintenance: Managing weight, inflammation, and insulin sensitivity helps mitochondria operate efficiently.

Nerve conditions and diabetes-related small-fiber neuropathy

Cold sensitivity is common in nerve injuries and diabetic neuropathy. Quantitative sensory testing studies show altered cold detection thresholds early in neuropathy—even before other tests turn positive—meaning nerves that sense cold can become miscalibrated. If you have diabetes or unexplained tingling/numbness with cold discomfort, this pathway is plausible.

Practical, research-grounded steps to feel warmer

These suggestions are adjuncts—not replacements—for medical evaluation where appropriate.

1) Check the “big three” labs (simple, high-yield)

Ask your clinician about ferritin/haemoglobin and TSH. These detect the most common, reversible medical drivers of cold intolerance. But you can also consider mitochondrial testing, and nutrient status.

2) Nurture non-shivering thermogenesis (gently)

Brief, regular mild cold exposure can condition the system: think 1–2 hours/day of “cool but tolerable” while clothed, or finishing a warm shower with a short cool rinse. Controlled trials show 7–10 days of such exposure reduce shivering, increase BAT activity, and improve comfort. If you have cardiovascular disease or Raynaud’s, clear a plan with your clinician first and avoid extremes.

3) Feed the furnace

• Iron-rich meals (plus vitamin C to enhance absorption) if ferritin is low.

• Adequate calories and protein. Prolonged energy deficits blunt cold tolerance; re-feeding reverses it.

• Carbohydrate availability supports shivering thermogenesis during acute cold; experiments show increased oxidation of carbs and fats under cold stress.

4) Move, then keep moving (and perhaps in the cold!)

Activity raises heat production immediately and can reduce reliance on vasoconstriction. While exercise doesn’t “fix” cold sensitivity overnight, integrating light movement breaks (brisk walking, gentle dynamic exercises) is a safe, effective way to warm up—then layer appropriately to retain that heat. Reviews of cold-exposed humans emphasise the combined roles of shivering and non-shivering thermogenesis in maintaining core temperature.

5) Dress for you, not the thermostat

Hands lose heat rapidly due to their high surface-area-to-volume ratio; prioritise head, neck, and hand insulation and use breathable layers that trap still air. People with lower body mass or less extremity fat benefit disproportionately from better gloves and liners.

6) If your fingers change colour, think Raynaud’s

Keep the entire body warm (core insulation reduces peripheral vasoconstriction), avoid sudden cold exposure, and manage stress. If episodes are frequent or severe—or you notice sores or skin changes—see a clinician to screen for secondary causes and discuss therapies.

Special Scenarios Worth Knowing About

• “I lost weight and now I’m freezing.” Lower mass and lower energy intake reduce heat production and insulation; this is expected and often improves with weight stabilisation and nutrition.

• “I’m older and colder.” Age-related changes in vasoconstriction and body composition increase vulnerability; emphasise layering, movement, and screening for reversible causes.

• “I have diabetes and my feet feel weird and cold.” Ask about small-fiber neuropathy testing; cold detection thresholds can reveal early nerve involvement.

The Bottom Line

Persistent cold sensitivity is common—and usually solvable—with a bit of sleuthing. The short checklist is:

1. Rule out iron deficiency and thyroid issues.

2. Consider Raynaud’s if colour-changing fingers/toes are part of the story.

3. Mind body composition, energy balance, and movement.

4. Condition your thermoregulation with safe, mild cold exposure if appropriate.

Your body’s heating system is adaptable. With targeted checks and small, consistent changes, most people can reclaim comfort even when the air turns crisp.

References

Mai et al., (2024) Iron supplementation and iron accumulation promote adipocyte thermogenesis through PGC1α-ATGL-mediated lipolysis, J Biol Chem;300(9):107690 (click here)

van der Lans et al., (2013) Cold acclimation recruits human brown fat and increases nonshivering thermogenesis Click here.

Yau et al., (2020) Thermogenesis in Adipose Tissue Activated by Thyroid Hormone, Int J Mol Sci 24;21(8):3020 (click here)

Temprano (2016) A Review of Raynaud’s Disease, Mo Med;113(2):123-6. (click here)

Stjernbrandt et al., (2018) Cold sensitivity and associated factors: a nested case-control study performed in Northern Sweden, Int Arch Occup Environ Health;91(7):785-797. Click here.

Kenney et al., (1995) Functional consequences of sarcopenia: effects on thermoregulation, J Gerontol A Biol Sci Med Sci:50 Spec No:78-85. Click here.

Morentin et al., (2014) Estradiol Regulates Brown Adipose Tissue Thermogenesis via Hypothalamic AMPK, Cell Metab. 1;20(1):41–53 (click here)

Takeda et al., (2023) Mitochondrial Energy Metabolism in the Regulation of Thermogenic Brown Fats and Human Metabolic Diseases, Int J Mol Sci 10;24(2):1352 (click here)