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6 Reasons for a Slow Metabolism

Metabolism is the rate at which your body uses energy–how fast your motor runs. When your metabolism is slow, all the processes in your body slow down. You might feel tired, depressed, cold, sluggish. You’ll find it hard to lose weight because your body will be more likely to store calories as fat, not burn calories for energy.

Here are some common causes of slow metabolism:

Too little sleep. While the occasional all-nighter forces your metabolism into high gear, chronic partial sleep loss (less then seven hours a night) has a profound effect on your metabolism. It affects glucose regulation, causing insulin resistance and elevated glucose levels. It leads to excessive food intake, storage of calories as fat, and obesity. It leads to decreased energy expenditure. You end up moving around less, as your body tries to conserve energy. Not getting enough sleep–or poor sleep quality– affects many of the hormones that control metabolism and energy intake, including cortisol, thyrotropin, leptin and ghrelin.

Too few calories. It’s well-known that drastic calorie restriction slows metabolism. But new research shows that even modest calorie restriction also slows metabolism, although less so. It may do so by impairing your body’s ability to convert T4, the inactive form of thyroid hormone, to T3, the active form that drives metabolism in your body. Exercise can counterbalance the metabolism-slowing effects of calorie-cutting.

Nutrient deficiencies. Many nutrient deficiencies will impair the body’s ability to generate energy. These include magnesium, iron, zinc, selenium, and most of the B vitamins. Too little protein, too, can slow metabolism and impair the body’s ability to make metabolism-boosting muscle. A good multi-vitamin and adequate protein can help make up for nutritional deficiencies.

Too little exercise. Exercise literally fans the flames, boosting energy metabolism while you’re active and for a few hours afterwards. Muscle-building, such as weight-lifting, has an added benefit. The more muscle you have, the higher your body’s resting metabolic rate. That helps you burn more calories 24/7.

Dehydration. Water is an important component of most of the chemical reactions that go on in your body, including energy metabolism. When you’re short on water, metabolism slows down dramatically, and you will soon feel the effects with sluggishness and fuzzy thinking. Make sure you drink enough every day. Carry water with you when exercising and for strenuous outdoors activities.

Low thyroid hormone function. Hypothyroidism is a well-known cause of slow metabolism. It can be detected by a test that checks blood level of Thyroid Stimulating Hormone. (TSH) However, you can still have inadequate thyroid hormone function even though you have normal levels of TSH. Your body may not be converting T4 (the inactive form of thyroid hormone) to T3 (the active form.) Or your cells may be resistant to T4. This condition is known as Wilson’s Temperature Syndrome (WTS.) The best way to find out if you have WTS is to take your body temperature. If it is consistently low, typically below 97.8 F. (36.56 C.) chances are good you have slow metabolism. People can recover from WTS with proper thyroid support, which often includes a trial of T3. You can discuss T3 therapy with your doctor and we will be happy to discuss your case with your doctor. Your doctor can call 800.420.5801. The object of T3 therapy is to normalize your oral body temperatures to average 98.6 (37 C.) during treatment. (See “How are body temperatures measured” for complete instructions.) When your temperature improves, you metabolism will return to normal. People whose metabolism is “reset” with T3 therapy often find that they can stop the T3 after a few months and their symptoms do not return because their temperatures stay normal!



Agnihothri RV, Courville AB, Linderman JD, et al. Moderate weight loss is sufficient to affect thyroid hormone homeostasis and inhibit its peripheral conversion. Thyroid. 2013 Jul 31.

Knutson KL, Spiegel K, Penev P. The metabolic consequences of sleep deprivation. Sleep Med Rev. 2007 Jun;11(3):163-78.

Vij VA1, Joshi AS. Effect of ‘water induced thermogenesis’ on body weight, body mass index and body composition of overweight subjects. J Clin Diagn Res. 2013 Sep;7(9):1894-6.


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