Sure, it’s easy today to gain weight. But if a healthy diet and exercising aren’t helping you shed pounds, you might look to your thyroid—especially if you are not particularly hungry, are fatigued much of the time, feel cold compared to others around you, experience muscle cramps, are losing hair, have high cholesterol, suffer dry and scaly skin, or feel blue. Women in their 50s who experience burning mouth syndrome may be at risk for thyroid problems. Having trouble conceiving? One fertility clinic finds that 25 percent of its patients have low thyroid function.

The Body’s Thermostat
Your thyroid, a small gland below the Adam’s apple in your neck, controls how quickly your body burns calories and utilizes energy. Thyroid hormones increase oxygen consumption, raise body temperature, accelerate pulse rates, dilate blood vessels, and stimulate both brain activity and muscular vigor.

If this gland secretes too few hormones, hypothyroidism with the symptoms listed above can occur. Approximately 13 million Americans have this condition—and close to 90 percent of them are women.

Holding On to Weight?
If you’re overweight or simply find it hard to lose pounds, you might want to test your thyroid function. However, most of the weight gain with hypothyroidism is moderate, and much of it is water weight, says board-certified endocrinologist James K. Rone, MD, who himself has an underactive thyroid.

“Could low thyroid [function] be a cause of obesity?” he asks. “In my opinion, absolutely; to think otherwise defies common sense. Low thyroid patients are tired, tired people don’t exercise, and lack of exercise leads to obesity. It’s also logical that the lower metabolic rate and reduced thermogenesis (body heat production) of hypothyroidism would result in fewer calories being burned, thus increasing fat storage of those calories,” he writes in The Thyroid Paradox.

Research in the Journal of Clinical Endocrinology and Metabolism shows that resting metabolic rate (calories burned when you do nothing) drops 15 percent when thyroid levels change from borderline high to mildly low. One recent study of more than 4,000 Danes finds that those with lower levels of thyroid hormones have a greater risk for obesity.

Hormone levels are “probably not the sole reason somebody weighs 300 pounds and can’t lose it,” Dr. Rone admits. “Even under the best circumstances, losing weight and keeping it off are difficult,” unless you’re disciplined about exercise and can avoid all those tempting, convenient calories in processed foods.

Testing, Testing
Even more difficult is getting a correct diagnosis of hypothyroidism. The simplest, least expensive way to start this process is to take your temperature: Place a basal thermometer under your arm and hold it there for 15 minutes every morning, while staying still and quiet (any movement can affect the reading). A temperature of 97.6º or lower may suggest an underactive thyroid. Log your temperature for five days, and if your readings are consistently low, contact your healthcare provider. Conventional physicians are more likely to diagnose depression than hypothyroidism, so it’s important to discuss all your symptoms and to bring your log.

The American Thyroid Association strongly advises adults over 35 to get tested for thyroid function every five years. Because accurate testing usually takes time and doesn’t seem necessary for the entire population, Dr. Rone suggests that all women over 50 have thyroid testing every five years and anyone over 35 with a family history of thyroid disease be tested every three to five years. In addition, testing is needed for pregnant women; anyone with a thyroid-linked disorder (depression, infertility, menstrual irregularity, and high blood lipid levels), goiter or thyroid nodules, or a past thyroid problem not currently being treated; and anyone who has received radiation or surgery to the thyroid.

The most frequently used test measures the serum levels of thyrotropin or thyroid-stimulating hormone (TSH). But this test alone may not be sufficient to determine if your thyroid is underactive. Dr. Rone suggests at least one other thyroid blood test, preferably an FT4 (free thyroxine or thyroid panel). Some experts also recommend an iodine absorption test since this mineral is linked to optimal thyroid function.

“Many people’s TSH falls within the conventional parameters for normal (0.3 to 6.0),” says medical journalist Lorna R. Vanderhaeghe. “Enlightened doctors refer to such people as having subclinical, or functional, low thyroid function.” Be aware that an endocrinologist will be more likely to treat low thyroid than a nonspecialist, which may help explain why less than 25 percent of those with low thyroid function are properly diagnosed and treated.

A Healing Lifestyle
Because weight tends to be an issue for people with hypothyroidism, it’s wise to avoid processed and refined foods, which tend to be high in calories, unwanted fats, and sugar. Some nutritionists suggest going easy on cabbage family (cruciferous) vegetables, especially if they’re uncooked, as they may further suppress thyroid function. Avoid chlorine and fluoride in drinking water—they can block iodine receptors in the thyroid. Instead drink filtered, steam-distilled water.

Almonds, avocados, bananas, dairy products, fish and chicken, dried fruits (apricots, dates, and prunes), eggs, pumpkin and sesame seeds, and whole grains (but not whole wheat if you’re gluten intolerant) are useful foods. For additional iodine, consider adding kelp and other sea vegetables to your diet. Vanderhaeghe also suggests liver-friendly foods—artichokes, beets, carrots, garlic, kale, leeks, lemons, and onions—to help with detoxification since environmental toxins have been linked to thyroid problems (see Causes of Hypothyroidism). Also, get plenty of vitamin D by going outdoors on sunny days and by making sure you include this vitamin in your daily supplements.
Stress reduction is key to managing thyroid problems, as the adrenal and thyroid glands are closely linked. “If the adrenals are exhausted, low thyroid hormones will result. If you have low thyroid function, it promotes stress on the adrenals,” explains Vanderhaeghe.

Added Support
Low blood levels of L-tyrosine are associated with hypothyroidism; supplementing with this amino acid may be useful when taken on an empty stomach with water or juice (not milk). B vitamin complex also supports thyroid function, and pantothenic acid enhances adrenal function, helping you handle stress better. If you don’t eat cold-water fish regularly, consider an essential fatty acid supplement.

The Ayurvedic herb ashwagandha increases T4 thyroid hormone production while guggul enhances conversion of T4 to the more active T3. Since these herbs works synergistically, take them together. Gentian and mugwort may also be useful, but if your healthcare provider recommends hormone therapy, be sure to discuss supplementation with a practitioner trained in herbal medicine and nutrition.