Thyroid medication helps restore normal thyroid hormone levels in people with hypothyroidism or underactive thyroid. While thyroid medicine is essential for managing hypothyroidism, some people may gain weight after starting treatment. This article explores whether too much thyroid medication can lead to weight gain.
Can hypothyroidism cause weight gain?
Hypothyroidism occurs when the thyroid gland does not produce enough thyroid hormones. Thyroid hormones help regulate metabolism, growth, and body temperature. When thyroid hormone levels are low, metabolism slows down, which can lead to fatigue, sensitivity to cold, constipation, dry skin, hair loss, and unexplained weight gain or difficulty losing weight.
In fact, unexpected weight gain is one of the most common symptoms of hypothyroidism. This weight gain is due to the slowing of the metabolism. Calories are not burned as quickly, which allows fat to accumulate.
Studies show that thyroid hormone deficiency can decrease the metabolic rate by 10-15%. This drop in metabolic rate makes weight gain more likely if calorie intake remains high.
One study found that people with untreated hypothyroidism tended to weigh about 10-15 pounds more than their peers without thyroid problems. Treatment with thyroid hormone replacement helped normalize their weight.
How does thyroid medication help with weight loss?
Thyroid medication supplies the thyroid hormone that the body is lacking. This helps reverse the metabolic slowing and symptoms of hypothyroidism.
Getting hypothyroidism under control with proper medication is important for achieving or maintaining a healthy weight. Restoring thyroid levels allows the metabolism to work optimally again so that calories can be burned at a normal rate.
Many people find it easier to lose weight once they start taking thyroid medication. A 2015 study found that thyroid hormone replacement therapy helped stabilize body weight and made weight loss easier in people with hypothyroidism.
However, thyroid medication is not a weight loss solution on its own. To lose weight, you still need to follow an overall healthy lifestyle with proper diet and exercise.
Can too much thyroid medication cause weight gain?
While normalizing thyroid levels with medication may promote weight loss, some people actually gain weight after starting treatment. This leads to the question of whether too much thyroid medication can cause weight gain.
In short – yes, excessive amounts of thyroid hormone from medication can lead to weight gain in some people with hypothyroidism. Here’s why:
It may push thyroid levels too high
The goal of hypothyroidism treatment is to restore thyroid hormone levels to the normal range – not overtreat and push levels too high. Taking too high of a thyroid medication dose can result in abnormally elevated thyroid hormone levels, a state known as hyperthyroidism.
While hypothyroidism causes a slowed metabolism, hyperthyroidism speeds the metabolism up. This revved up metabolic state can cause weight loss. But it is also associated with other symptoms like anxiety, rapid heartbeat, tremors, sweating, diarrhea, and muscle weakness.
If the hyperthyroidism persists, the body may adapt by actually slowing the metabolism down. This is called “down-regulation.” The slower metabolism and tiredness due to hyperthyroidism can ultimately facilitate weight gain.
It may disrupt the balance of T3 and T4
There are two major thyroid hormones – T4 (thyroxine) and T3 (triiodothyronine). T4 is considered the storage form, while T3 is the more biologically active form that acts on tissues and cells. The thyroid gland mainly secretes T4, and enzymes in the body convert it to T3 as needed.
The most common thyroid medications only contain T4 (levothyroxine, Synthroid, Levoxyl.) But some people have trouble converting T4 to enough T3. Supplementing with only T4 may not properly balance their T3 levels, leading to persistent hypothyroid symptoms.
Taking too much T4 medication can also disrupt the T3 balance. This is because excess T4 can overload the conversion system and actually block T3 production. Insufficient T3 can then contribute to low energy, fatigue, and weight gain.
Other effects on metabolism
Excess thyroid hormone may also impact weight by:
- Increasing insulin resistance. Higher insulin levels can promote fat storage.
- Raising stress hormone cortisol. Elevated cortisol slows metabolism.
- Lowering leptin. Leptin is a hormone that helps regulate appetite and metabolism.
These metabolic changes associated with too much thyroid medication work against weight loss efforts.
What is the optimal thyroid level for weight loss?
The first goal of hypothyroidism treatment should be restoring thyroid function to normal levels – not maximizing thyroid hormones for the purpose of weight loss. Pushing thyroid hormone levels too high can lead to symptoms of hyperthyroidism.
However, research has looked at whether small variations in normal thyroid levels affect weight. These studies found that among people without thyroid disease, those with TSH levels at the lower end of the normal range tended to have lower body weight.
TSH stands for thyroid stimulating hormone. This is the hormone secreted by the pituitary gland to stimulate the thyroid. High TSH indicates hypothyroidism, while low TSH indicates hyperthyroidism. Normal TSH reference range is around 0.5-4.5 to 5 mIU/L.
Based on these findings, some doctors target the lower half of the normal range when treating hypothyroid patients who want to lose weight. A TSH around 1-2 mIU/L may optimize the metabolic benefits and promote easier weight loss.
However, it is unclear if targeting this lower normal range offers much added benefit for weight compared to standard levothyroxine therapy restoring TSH to mid-range.
More importantly, dosage should be adjusted carefully based on symptoms and avoided pushing levels to hyperthyroidism. Periodic testing helps prevent overtreatment.
Tips for weight loss on thyroid medication
To sum up, excessive thyroid medication can contribute to weight gain in some cases. However, the right thyroid treatment tailored to the individual offers the best chance of maintaining a healthy weight.
Here are some tips for weight loss when taking thyroid medication:
- Work with your doctor to find the optimal thyroid medication type (T4, T3, or combination) and dose for your body.
- Get thyroid hormone levels, including TSH and free T4, tested regularly to make sure medication dose is ideal.
- Evaluate medications, supplements, or health conditions that could interfere with thyroid function.
- Adopt an overall healthy lifestyle – calorie-controlled diet, regular exercise, good sleep habits.
- Aim for the lower end of the normal range for TSH, around 1-2 mIU/L.
- Consider adding T3 thyroid medication if not responding well to T4 alone.
- Be patient and persistent. Restoring thyroid balance can take time.
Conclusion
Untreated hypothyroidism can make weight gain more likely. Getting on proper thyroid hormone replacement helps normalize metabolism and makes weight management easier.
However, excessive amounts of thyroid medication can potentially work against weight loss efforts in some cases. Too much thyroid hormone may speed up metabolism initially but can eventually disrupt metabolic function and thyroid-weight hormone balance.
Dosage is key – the goal is to restore normal thyroid function, not push thyroid levels too high. Regular testing and follow-up helps determine the optimal dosage and thyroid hormone levels for overall health and weight.