Others can rely on hyperthyroidism to lose weight, why are you getting fat?

*Only for medical professionals to read for reference to break prejudice! Although they are all hyperthyroidism, the specific situation needs specific analysis.
Hyperthyroidism does not mean getting thinner! Due to hypermetabolic syndrome caused by elevated thyroid hormone levels, weight loss is a common complaint in many patients with hyperthyroidism (hyperthyroidism).

However, clinically, from time to time, patients with hyperthyroidism who have no significant weight loss or even increase in weight are encountered.

This is undoubtedly a "bolt from the blue" for patients who hope to lose weight by taking advantage of the "dongfeng" of hyperthyroidism.

So, if others can rely on hyperthyroidism to lose weight, why does the scale say that you are fat? In clinical practice of hyperthyroidism and weight change, when patients experience unexpected weight loss, especially those with typical symptoms such as palpitations, anxiety, irritability, sweating, and tremor, clinicians often consider the possibility of hyperthyroidism.

Among untreated patients with hyperthyroidism, 67 to 90% experience weight loss.

At the beginning of the first hyperthyroidism treatment, the patient’s average weight was roughly 16% less than the weight before the onset of disease [1-3].

In a study, the ratio of normal weight (BMI 18.
5-25.
0 kg/m2) and underweight (BMI <18.
5 kg/m2) among patients of different genders when they first went to the doctor due to hyperthyroidism is shown in the following table [3].

However, weight loss is not the eternal theme of hyperthyroidism.
About 10% of patients with hyperthyroidism can gain weight [1], and sometimes even overweight or obesity.

Weight gain may be the result of multiple factors such as the treatment of hyperthyroidism, the patient's own diet and calorie intake, and the outcome of hyperthyroidism.

Hyperthyroidism treatment and weight gain The mechanism of weight loss caused by hyperthyroidism is the increase in the basal metabolic rate caused by the increase of thyroid hormone, but after the treatment of hyperthyroidism, as the thyroid hormone level drops, the effect of hormones on the metabolic rate will gradually disappear.

Therefore, it is not difficult to understand that the weight of patients with hyperthyroidism may increase after treatment, and the treatment of hyperthyroidism may "overcorrect" and increase the risk of obesity.
This is more obvious in patients with severe hyperthyroidism who recover after treatment.

In the early stage after receiving different treatments for hyperthyroidism, the weight of the patient may gradually increase, and the weight may increase by 5 to 10 kg one year after treatment, and the weight may continue to increase in the subsequent treatment stage [1].

In one study, the increase in the proportion of obesity in patients with hyperthyroidism after 2 years of treatment was even as high as 32% [4].

In a large prospective cohort study of 1373 patients with hyperthyroidism followed up for an average of 23 months in the United Kingdom, during the treatment of hyperthyroidism, the weight of patients with hyperthyroidism increased by an average of 6.
0kg, and the weight gains of more than 5% and 10% were 65%, respectively.
38%.

Men (8.
0kg) have a greater weight gain than women (5.
5kg).

Compared with the general population, the risk of obesity in male and female patients is increased by 70% and 30%, respectively [3].

In addition, previous history of obesity, hyperthyroidism caused by Graves' disease, and follow-up time may also be predictors of weight gain [5].

Different treatment options for hyperthyroidism and weight gain The treatment of hyperthyroidism mainly includes oral antithyroid drugs, iodine 131 treatment or thyroidectomy.

Hypothyroidism (hypothyroidism) is a common complication of these treatments, and hypothyroidism is another common cause of weight gain.

▌ Oral antithyroid drug research shows that patients' weight increases significantly after oral antithyroid drug treatment, especially in the first 6 months.

During the treatment and follow-up period of nearly 2 years, the weight of patients treated with oral antithyroid drugs increased by an average of 5.
4 kg.
After oral drug treatment, the "overcorrection" effect was more prominent, so the risk of obesity increased.

▌Iodine 131 treatment The weight of patients with normal and hypothyroidism after iodine 131 treatment increased by an average of 5.
2kg and 7.
1kg, respectively.

Compared with patients with normal thyroid function after oral antithyroid drug treatment or iodine 131 treatment, patients with hypothyroidism after iodine 131 treatment have greater weight gain.

However, there was no significant difference in weight gain between patients with normal thyroid function after 131 iodine treatment and those treated with oral antithyroid drugs [3].

▌ Thyroidectomy Another study showed that compared with patients receiving other treatments, patients after thyroidectomy gained more weight.

During the follow-up period of at least half a year, the weight of patients after thyroidectomy increased by an average of 10.
27kg [5].

However, the sample size of the aforementioned studies is relatively small.

A systematic review and Meta analysis published by Huynh CN in 2021 showed that 3164 patients were followed up for an average of 23.
8 months.
Overall, the weight of the patients increased by only 2.
13kg, and age and weight change were negatively correlated [6].

It can be seen that patients who underwent thyroidectomy only gained a slight weight gain, which may also be related to the differences in race, follow-up time, and surgical indications involved in different studies.

Compared with hyperthyroidism caused by toxic nodular goiter or other unknown causes, patients with Graves disease hyperthyroidism after treatment have more significant weight gain.

This may be related to the higher levels of free T4 in patients with Graves disease [3].

The correlation between the treatment of Graves disease and weight gain is also common in children.
Many children become overweight or obese during treatment.
The risk factors include the severity of hyperthyroidism, the duration of iodine 131 treatment, and age [7].

Hyperappetite and weight gain in patients with hyperthyroidism Hyperappetite and gluttony are typical gastrointestinal manifestations of patients with hyperthyroidism.
Hyperappetite leads to an increase in the patient’s daily calorie intake by about 700kcal, which may be related to the activation of the hypothalamus-pituitary-thyroid axis [1].

To sum up, the impact of hyperthyroidism on body weight has great individual differences, and not all patients can realize the good wish of "relying on hyperthyroidism to lose weight".

The etiology, severity and treatment of hyperthyroidism may be related to the weight gain of patients with hyperthyroidism.
In particular, patients with hypothyroidism after treatment with iodine 131 are more likely to gain weight and increase in a greater extent.

Therefore, the treatment of hyperthyroidism is also related to the risk of obesity.

The above conclusions remind clinicians that in clinical practice, in addition to paying attention to the weight loss of patients with hyperthyroidism at the initial stage of onset, attention should also be paid to the risk of overweight or obesity during treatment.

Before providing patients with different hyperthyroidism treatment options, they should also pay attention to the risk of weight gain, which can also remind patients with hyperthyroidism to control their weight through diet and lifestyle changes during treatment.
The latter is also important for hyperthyroidism-related weight gain.
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