The cause of low metabolism is not always something that can easily be determined. Sometimes low metabolism is related to heredity, sometimes to illness, and sometimes just to not eating the right foods.
Metabolism and Thyroid

In the last decade or so, people have come to know more about the problem of thyroid deficiency and how widespread it is. Hypothyroidism, which occurs when the body is not producing enough thyroid hormone, is responsible for a whole host of symptoms, including low metabolism.

Some people with thyroid problems have very obvious symptoms, while others do not. There is such a range of possible symptoms that many other ailments may be tested for first before levels of thyroid hormone are checked. Some of the other symptoms people with hypothyroidism might include:

Weight gain
Anemia
Muscle cramps and joint pain
Fatigue
Depression
Migraines
Impaired memory
Increased sensitivity to heat and cold
Paleness
Brittle fingernails
A blood test can determine if someone has a thyroid problem, and there are several different treatments that should make this cause of low metabolism relatively easy to tackle.

Other Causes of Low Metabolism

Of course not everyone who has a low metabolism has a thyroid problem. The fact is, most people's metabolisms decrease as they age There are all sorts of reasons for this, some of which are beyond our control. But there are some things you may do that can be the cause of low metabolism, so changing your behavior may change the way you feel.

Diet
One of the biggest factors in metabolism is actually what we eat. If you're fasting or on a very low-calorie diet, odds are you have slowed down your metabolism to the point that you still aren't losing a lot of weight even though you're miserable from not eating.

The body needs nutrients and calories in order to work properly, and a lot of research seems to indicate that eating more often is better than eating only a couple of meals a day. That's because it takes energy (calories) to digest and process food, and it keeps blood sugar levels more even when you eat regularly, which also keeps you feeling full.

Not only does how often you eat make a difference, what you eat can have an impact. Lots of high-sugar foods can mess with your metabolism because of the fluctuation of blood sugar. There are also foods that increase metabolism that should be consumed more often.

Water
Drinking enough water is important for a lot of reasons, but not being properly hydrated can really slow your metabolism. Most of the body's functions, including digestion and metabolism, require water. If you're not getting enough, your body can't function at its peak.

It's easy to start drinking more water if you make a habit of carrying a bottle or mug of water with you through the day. Replace sugary sodas with water and you'll be doing your body even more of a favor.

Exercise
When your body is in good shape, everything works better. Having more muscle raises your body's resting metabolic rate, or the number of calories burned just through regular function of the body. A regular regimen of weight training can allow you to burn around 100 more calories each day. That may not sound like much, but if all other things remain equal that would lead to a weight loss of about 10 pounds in a year.

Stress
Stress may also play a role in decreasing metabolism because when the body is stressed, systems start working less efficiently. Also, people tend to overeat, eat the wrong things and not exercise when they are stressed, so it all goes together.

Ways to Improve Metabolism

Drink more water.
Eat smaller, more frequent meals.
Cut back on sugary foods and beverages.
Try to exercise at least 30 minutes a day most days of the week.
Do some weight training if you're not doing so already.
Try to cut some stress from your life or learn better ways to handle it.
If something still seems wrong, check with your doctor about getting your thyroid tested.