Thyroid hormones have been used as a weight loss tool in the past. Many studies have shown that excess thyroid hormone treatment can help produce more weight loss than can be achieved by dieting alone. However, once the excess thyroid hormone is stopped, the excess weight loss is usually regained.
While thyroid medication may help people manage their condition, it is unlikely to dramatically change a person's weight. In people without thyroid disease, taking thyroid hormones can be dangerous. It may cause an overactive thyroid, called hyperthyroidism.
While undertreatment with levothyroxine can lead to weight gain, overtreatment can result in weight loss as well as adverse effects including bone and muscle loss and heart problems, especially arrhythmias. Once the excess hormone is stopped (that is, the dose is adjusted downward), the weight is typically regained.
There are many risks of taking too much levothyroxine. The signs and symptoms of thyroid overmedication include anxiety, diarrhea, depression, elevated heartbeat, elevated blood pressure, fatigue, irritability, difficulty concentrating, difficulty sleeping, being overheated, and unprompted or unintentional weight loss.
Introduction
The common clinical signs following thyroxine overdose can either be limited to tachycardia, agitation, nervousness, insomnia, anxiety, tremor [2], or severe features, though less likely, like thyroid storm involving cardiac, neurological, respiratory and thermoregulatory center [3].
Does Levothyroxine Cause Weight Gain? Both weight gain and weight loss are possible side effects. Many people do not take the right dosage of levothyroxine, and both undertreatment and overtreatment can have an effect on weight.
Thus, excess thyroid hormones or taking a larger dose of thyroid medication is unlikely to lead to dramatic weight changes.
If you take thyroid replacement hormones (levothyroxine) after surgery or radioactive iodine, you can take two pills at the same time if you forget one. While this is safe, it's better if you remember to take it every day.
The symptoms of too little thyroid medication may feel similar to getting a cold. For example, you may feel a sudden surge of shivers, cold hands and feet, and even a sore or swollen throat. One of the signs of low thyroid hormone is brain fog.
As with most medications, if you've gained or lost weight, you may need to adjust the dose of your thyroid medication. Your provider will calculate how much to add or take away based on your weight change and monitor how well you do with the new dosage.
Common side effects of levothyroxine include heat intolerance, a fast heart rate, and diarrhea. More serious levothyroxine side effects are also possible. If you experience side effects like tremors or mood changes, talk to your healthcare provider as soon as you can.
Hyperthyroidism speeds up the body's metabolism. That can cause many symptoms, such as weight loss, hand tremors, and rapid or irregular heartbeat.
With thyroid fatigue, you may feel like you can't get through a day without a nap. You may sleep more than usual but still feel completely exhausted. You may not even have the energy to exercise. At times, you may fall asleep during the day or very quickly at night.
It's absorbed slowly, and levels tend to stabilize, so splitting a dose doesn't significantly impact absorption or symptom relief. If you're taking levothyroxine – the synthetic form of the T4 hormone – there's no clear benefit to taking it more than once a day.
Hypothyroidism slows down your metabolism, making it more difficult to lose extra pounds and maintain a healthy body weight.
Weight gain
Even mild cases of hypothyroidism may increase the risk of weight gain and obesity. People with the condition often report having a puffy face as well as excess weight around the stomach or other areas of the body.
When you start taking thyroid medication like levothyroxine, don't expect instant weight loss. The first barrier is getting the right dose of thyroid medication. Once you have reached your ideal dose, you may notice some weight loss after around three to six months of continuous use.
Adults usually start with a dose between 50 micrograms and 100 micrograms taken once a day. This may be increased gradually over a few weeks to between 100 micrograms and 200 micrograms taken once a day. Some people, such as over-50s or people with heart disease, may start on a lower dose.
And in a study where they compared equivalent doses of T4 to T3, T3 resulted in significant weight loss when substituted for T4. (T3 also reduced cholesterol better.) The results were modest (about 4 pounds on average, or about a 50 calorie-per-day change in resting metabolic rate) but could add up over time.
The hormone leptin is produced by fat cells and is secreted into our bloodstream. Leptin reduces a person's appetite by acting on specific centres of their brain to reduce their urge to eat.
You feel more tired while taking Levothyroxine because the hormones in your body have been effectively reduced. Thyroxine is produced by the thyroid and is responsible for activating metabolic processes, energy production, and many other functions in your body.
The long-term effects of thyroid medication include weight fluctuations, sensitivity to heat, joint pain, changes to your menstrual cycle, and possibly even autoimmune dysfunction.