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| Obesity and Thyroid Disorder |
Even though an under-active thyroid may lead to weight gain and even obesity, in some cases, there is evidence that obesity itself can potentially lead to thyroid dysfunction. Since weight loss frequently will lead to a normalization of the TSH, there is evidence that an increased TSH can be a consequence of obesity. The abnormality of thyroid hormones is responsible for weight gain since they control body metabolism. Several studies have reported a positive correlation between increased BMI and thyroid conditions. It is clear that hypothyroidism can cause obesity, but the phenomenon of how obese people are more prone to thyroid-related conditions is still not well understood.
Another factor that can be the link between obesity and thyroid disorder is the leptin-a starvation hormone (the hormone made by adipose cells which also influences TSH release). Leptin a hormone that is produced by adipocytes (fat cells) regulates the energy balance by inhibiting hunger and this can be the possible link between BMI and TSH. Leptin hormone is an important neuroendocrine regulator and therefore it plays an important role in the regulation of thyroid homeostasis. There is a negative correlation between the levels of thyroid hormones and leptin. Whereas, the levels of TSH are positively correlated with obesity thereby resulting in a positive correlation with leptin levels. Since leptin concentrations influence TSH release, leptin seems to be a promising link between obesity and alterations of thyroid hormones. This clearly shows the association between BMI and TSH as reported in clinical studies. With the increase in weight, a moderate increase in T3 and TSH levels were noted regardless of insulin sensitivity and metabolic parameter.
Obesity:
Choosing an elevator over stairs, excessive consumption of junk food, or overconsumption of alcohol, all these factors lead to obesity. Obesity has increased significantly since the 1970s. As per WHO, worldwide obesity has nearly tripled since 1975. Presence of extra body fat or having a body mass index (BMI) of more than 30 kg/m is characteristic of obesity. It may be due to consuming more calories than required, the genetic makeup of your body, your lifestyle, less sleep, etc.
"Obesity is the terror within" - Richard Carmona
Thyroid:
Apart from obesity, thyroid disorder is another factor that is steadily affecting many individuals across all age groups. One out of three individuals has a thyroid-related condition that affects the production of thyroid hormones. The hormone produced by the thyroid gland, thyroxine (T4) and triiodothyronine (T3) is stimulated by the thyroid-stimulating hormone (TSH). Thyroid conditions may be due to iodine deficiency, autoimmune diseases like Graves' disease or Hashimoto's thyroiditis, toxic nodules, inflammation of the thyroid, etc.
DOES OBESITY AFFECT THYROID FUNCTION?
According to the study from 2006 based on 6164 adults, higher BMI was linked to higher TSH, especially central obesity (abdominal obesity). Lower free thyroxine (FT4) and higher TSH levels are associated with fat accumulation in slightly overweight individuals. Another study was conducted with an aim to evaluate the relationship between TSH, free T4 (FT4), and free T3 (FT3) levels and weight measured by body-mass index (BMI) in a large database of pediatric and adolescent patients. Studies have reported that obese patients are found to have slightly higher blood levels of TSH as compared to normal-weight patients. Moreover, TSH and T3 levels may be increased in obese but T4 levels remain unchanged. T3 levels return to normal after weight loss. These findings suggest that weight gain and obesity result in changes in the thyroid function, rather than the change in the thyroid function being the primary event resulting in obesity. In addition to an elevated TSH, elevated free T3 levels were found to be positively associated with obesity in some of these people with obesity. Free T4 has shown to be correlated inversely with obesity. Though the elevated TSH and low free T4 levels in the hypothyroid condition make sense, the elevated free T3 levels do not make sense for someone with a hypothyroid condition. The cause of elevated free T3 levels is not known exactly, although there are a few theories, such as an increased deiodinase activity in individuals with obesity which results in an increase in conversion of T4 to T3.
To summarize, obesity and weight gain are common with thyroid and autoimmune thyroid conditions. Though it is often assumed that an imbalance in thyroid hormone, more precisely a hypothyroid condition, is responsible for the increase in weight, sometimes the weight gain is what also leads to the development of a thyroid or autoimmune thyroid condition. The problem is that many people think of obesity as being a “static” condition. In other words, an increase in adipose tissue will result in inflammation, and in some cases, this inflammation can be severe enough to trigger an autoimmune response. As a result, many times correcting the thyroid hormone levels alone is not sufficient to address obesity.
Thyroid Disorders That Cause Obesity
Thyroid hormones regulate your body's metabolism. Fluctuations in the levels of thyroid hormones are responsible for changes in body weight. Oversecretion of thyroid hormones (Hyperthyroidism) leads to sudden weight loss, whereas under secretion (Hypothyroidism) leads to sudden weight gain. Hypothyroidism leads to low basal metabolic rate (BMR) making individuals more prone to weight gain. An Individual's weight gain varies with the severity of hypothyroidism and massive weight gain is rarely seen. In patients suffering from hypothyroidism, excessive fat is not the only reason for weight gain but the accumulation of salt & water can also be the cause.
Obesity & Thyroid Cancer
Obese people might also have a greater risk of thyroid cancer. Actually, there is evidence that being obese or overweight is related to a modestly increased thyroid cancer risk. Cases of obesity-linked with thyroid cancer have increased significantly in the last few decades. Based on origin, appearance, or characteristics, there are mainly 4 types of thyroid cancers:
1. Papillary Thyroid Cancer
2. Follicular Thyroid Cancer
3. Medullary Thyroid Cancer
4. Anaplastic Thyroid Cancer
Among all the thyroid cancers, papillary thyroid cancer is the most commonly diagnosed."
One study in the US reported obesity to be an independent risk factor for developing thyroid cancer.' Another study demonstrated that the risk of developing thyroid cancer in women is greater in overweight and obese (BMI > 25 kg/m) than the normal weight individuals and excess ingestion of calorie, proteins and carbohydrates might be the link between obesity and high risk of papillary and follicular thyroid cancer."
DIAGNOSIS- Prevention is better than cure
A set of blood tests should be done regularly for diagnosing obesity-related conditions especially if you are a middle-aged individual and experiencing symptoms like fatigue, joint pains, concentration problems, weight loss/gain, high blood pressure, frequent urination, nervousness, etc.
Thyroid Profile- Most of the thyroid hormones produced in the body bind to the protein and some of them are unbound in your blood, hence in free form. T3 & T4 test measures the total T3 & T4 count present in your blood. A TSH test can be done in order to measure the TSH levels.
Lipid Profile-This profile measures the level of total cholesterol and triglycerides levels in your blood. Lipid profile includes the test for Total Cholesterol, HDL Cholesterol, LDL Cholesterol, and Triglycerides.
Blood Sugar Test- This test helps in monitoring your blood glucose level. It is an essential test if you have diabetes.
Cardiac Risk Markers Profile-This test assesses your cardiovascular condition and determines the exact condition of your heart. Tests like ApolipoproteinA1, Apolipoprotein-B, Lipoprotein, hsCRP, and Apo B/Apo A1 ratio constitute the Cardiac Risk Marker profile.
During obesity, gaining extra weight can affect your body in many ways including your thyroid hormone levels. This alteration leads to various disorders related to thyroid or even cancer in some cases. It is important to take care of your health as it is only you who will be looking after yourself till the very end. Regular health checkups can help you take timely precautionary actions to prevent such conditions.
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