Without losing time:
1. You have low iron levels
If you’re constantly asking yourself, “Why am I always cold?” iron deficiency anemia could be to blame. Red blood cells need iron to carry oxygen in the blood, and low iron levels could harm your circulation. The coldness in the extremities (hands and feet) is more pronounced because the body is intelligent, so it first diverts blood to vital organs like the heart and brain. Meat is the most common dietary source of iron. Leafy greens and legumes are good sources, but pair them with a vitamin C-rich food like red bell peppers for maximum absorption.
2. You need more vitamin B12
People might assume you’re not getting enough iron when it’s really a B12 problem. Vitamin B12 anemia can cause coldness, numbness, and low energy. Like iron, most foods rich in vitamin B12 are animal products, so vegetarians may have a hard time getting enough. Vitamin B12 is found in eggs, yogurt, and cheese. Vegans can sprinkle nutritional yeast, a cheese-flavored powder, over popcorn or baked potatoes. If you’re vegan, ask your doctor to check your vitamin B12 levels regularly to make sure you’re getting enough.
3. You have a thyroid condition
When your body doesn’t produce enough thyroid hormone to regulate your metabolism, you can end up feeling cold all the time. If you experience other symptoms of thyroid disease, such as hair loss, constipation, weight gain, or fatigue, see a doctor for a blood test to check for hypothyroidism. 
4. You have low body weight
Being underweight could mean that you are always cold for two reasons. Fat works as an insulator, so having less fat can mean you can’t keep warm well. Also, cutting calories can slow your metabolism, giving your body less energy to heat itself. Your body is smart and won’t want to use energy if it’s worried that energy is in short supply. If you’re trying to gain weight, eat high-calorie foods with good fats, such as nut butters, full-fat Greek yogurt, and dried fruit.
5. You skip sleep
Not getting enough sleep is another reason why you’ll always be wondering, “Why am I always cold?” Although research on sleep and feeling cold is mixed, chronic fatigue can slow your metabolism and make you feel cold during the day. Also, your body temperature fluctuates at night and your body gets used to that cycle. If you stay up later than usual, your core body temperature can drop for the same amount of time as it would if you were asleep.
6. You are dehydrated
When your body doesn’t have enough water, it can’t circulate blood as effectively. Water also retains heat, which means that dehydration could leave your body without the temperature retention benefits of H2O. To stay hydrated, try to drink half your weight in ounces of water. For example, if you weigh 150 pounds, try to drink 34 ounces throughout the day.
7. You could be experiencing complications from diabetes.
Diabetics can develop peripheral neuropathy which damages the nerves in charge of the senses. This complication of diabetes means that you can always feel cold or achy or hot for seemingly no reason. It may not be physical, but just the feeling of being cold. It’s just a mistake in the message sent to the brain from the feet or hands. 
8. You don’t eat enough fat
There’s a reason you crave hot, hearty meals in the winter. Fat helps us feel full and helps us feel warmer. Low-fat diets that replace healthy foods like avocados, nuts, and seeds with refreshing foods like fruits and juices can leave you feeling cold.
9. You have Raynaud’s
A small percentage of the population suffers from Raynaud’s, a rare blood vessel disorder that causes arteries in the hands, feet, and face to spasm. When exposed to cold, the spasm worsens circulation to those areas and they tend to feel colder.
10. You have poor circulation
In some cases, poor circulation is caused by a chronic condition such as vascular disease or peripheral arterial disease. If your extremities are cold but cannot be traced to a chronic condition, you may have naturally poor circulation and always feel cold. It is advisable to exercise regularly and try acupuncture to restore sensation to the hands and feet.
11. You don’t have enough muscle
Muscle mass produces heat and keeps the rest of the body warm. Make sure you stay active and maintain a good exercise routine.
12. You are a woman
There is anecdotal evidence that women often feel colder than men, but there isn’t a great deal of scientific evidence. That said, a 1998 study found that women’s core temperatures tend to be about 0.4 degrees Fahrenheit warmer than men’s, their hands are nearly 3 degrees cooler on average, according to a University of Utah study. . It’s not a huge difference, but it could be why women feel colder.