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Lack of Thyroid Hormones Explains Why Some People Cannot Lose Weight

Diets rarely help people to lose weight permanently, so exercise gives you your best chance to lose excess weight and keep it off. However, some people cannot lose weight, no matter how much they exercise. Researchers at the University of Pittsburgh showed that overweight people who do not lose weight when they follow an exercise program are likely to suffer from low thyroid function, and therefore should be able to lose weight if they take thyroid hormones (Medicine & Science in Sports & Exercise, February 2009). I think this is a very important study so this issue of the eZine is a little longer than usual.

When you eat, blood sugar levels rise. Your pancreas responds by releasing insulin into your bloodstream which drives sugar into cells where it can be used for energy. As you gain weight, fat cells fill with fat. This blocks insulin receptors so your cells cannot respond adequately to insulin and blood sugar rises to higher levels. This causes your pancreas to release even more insulin. Too much insulin can harm you. It acts on your brain to make you hungry, eat more and gain more weight. It constricts the arteries leading to your heart to cause heart attacks.

As I explained last week, muscles become extraordinarily responsive to insulin when you exercise so you need far less insulin to drive sugar from your bloodstream into cells. Insulin levels go way down with exercise, but the effect gradually tapers off in about 18 hours. So you have to exercise every day to maintain the benefit of lowered insulin levels, and overweight people who exercise every day usually lose weight.

However, some overweight people cannot lose weight no matter how much they exercise. This study shows that many of these people have low thyroid function which prevents the cells from responding to insulin and drives both insulin and blood sugar to very high levels.

Doctors do not diagnose low thyroid function by measuring thyroid hormone levels. Instead, they do a blood test called TSH that measures the brain's response to thyroid hormone levels. The brain produces TSH to stimulate the thyroid gland to make more thyroid hormone. TSH rises to high levels when the brain senses that there is not enough thyroid hormone in the body.

For many years, doctors have argued among themselves whether to treat people who have normal levels of thyroid hormones and very high levels of TSH (called subclinical hypothyroidism). This exciting new study shows that people who have high levels of TSH but have normal levels of thyroid hormone have muscles that do not respond to insulin adequately when they exercise. This means that they develop high levels of insulin and blood sugar, become overweight, diabetic, and often die of heart attacks.

If you are person who has extreme difficulty losing weight, ask your doctor to draw a blood test called TSH. If it is above 3.0, you probably will benefit from taking thyroid hormone. However, you must be careful not to take too much because overdoses of thyroid cause osteoporosis. Your thyroid dose should be adjusted to keep your TSH values between 0.3 and 3.0.


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Update on high insulin levels and cancer:

Women who have high levels of insulin are at high risk for developing breast cancer (Journal of the National Cancer Institute, January 2009). Insulin stimulates breast cells to grow. Women who are most likely to have high levels of insulin are those who are obese, store fat primarily in their bellies, do not exercise, eat lots of refined carbohydrates (sugar and flour), and lack vitamin D. Furthermore, people with diabetes who get cancer are 40 percent more likely to die earlier than cancer patients who are not diabetic (Journal of the American Medical Association, February 2007). Dr. Frederick Brancati of Johns Hopkins University in Baltimore combined the results of 23 studies involving about 125,000 people in 10 countries including the United States, Australia and the Netherlands. People with high blood sugar levels are at increased risk for cancers of the uterus, breast, colon, pancreas, endometrium, liver and bladder. Those with diabetes have a 76 percent higher risk of death from cancer of the uterus, a 61 percent higher risk for breast cancer, and a 40 percent increase for colon cancer. Furthermore, diabetics are at higher risk for heart disease, stroke, kidney damage and blindness.


Recipe of the Week: Lentil Tabbouleh Salad

You'll find lots of recipes and helpful tips in The Good Food Book - it's FREE

June 22nd, 2013
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About the Author: Gabe Mirkin, MD

Sports medicine doctor, fitness guru and long-time radio host Gabe Mirkin, M.D., brings you news and tips for your healthful lifestyle. A practicing physician for more than 50 years and a radio talk show host for 25 years, Dr. Mirkin is a graduate of Harvard University and Baylor University College of Medicine. He is board-certified in four specialties: Sports Medicine, Allergy and Immunology, Pediatrics and Pediatric Immunology. The Dr. Mirkin Show, his call-in show on fitness and health, was syndicated in more than 120 cities. Read More
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