Your body controls its temperature basically like this: Your hypothalamus, a part of your brain, acts as your body's thermostat, working with other temperature-regulating parts of your body (your skin, blood vessels and sweat glands) to adjust your temperature ever so slightly as needed to maintain that healthy 98.6 degrees Fahrenheit (37 degrees Celsius). How hydrated you are (the better hydrated, the better your temperature control), how much body fat you have (lose body fat, and lose its heat-retaining benefits) and how toned your muscles are (better toned muscles generate more heat even when you're resting) also all contribute to how hot or cold we feel.
And so does what you eat.
Researchers have found that people who are B vitamin deficient may find themselves more sensitive to cold temperatures.
B vitamins are considered the "energy vitamins," because they play an important role in how your body converts food into energy. But their benefits don't stop there. B vitamins are also important for a healthy immune system, healthy red blood cell production, healthy digestion and a healthy nervous system. When the body is deficient in vitamin B12, a condition known as pernicious anemia, it can't make healthy red blood cells that are needed to carry oxygen throughout your body, and the result is coldness in your hands and feet and a general intolerance to cold temperatures. A B12 deficiency can be caused by malabsorption problems, autoimmune diseases, gastric bypass surgery, the lack of the hormone needed for the body to synthesize B12 (this is called the intrinsic factor) or by a diet lacking in balanced nutrition.
And speaking of balanced nutrition, iron also plays a role in whether or not you're feeling chilled, and it's iron-deficient anemia rather than pernicious anemia that you're more likely to hear about. Symptoms of an iron deficiency (iron-deficient anemia) may include fatigue, weakness and dizziness as well as pale skin and intolerance to cold temperatures (and cold hands and feet). If you're bothered by cold intolerance and warm beverages and an extra blanket aren't enough, consider seeing your doctor who will be able to pinpoint the problem.