Can an underactive thyroid explain why weight loss isn't working?

An underactive thyroid can contribute to weight gain, but as a sole cause it rarely explains why weight loss fails. With hypothyroidism, the metabolism slows down, causing the body to burn fewer calories at rest. However, the weight difference this causes is often more limited than people expect. The questions below provide a clear picture of what the thyroid does and does not do to your weight, and what you can do if, despite everything, losing weight does not work.

What does the thyroid do to your weight?

The thyroid gland regulates metabolism by producing thyroid hormones that determine how fast the body uses energy. In a properly functioning thyroid, this process is in balance. When the thyroid produces too little hormone, the metabolism slows down and the body burns fewer calories at rest, which can lead to weight gain.

Thyroid hormones, particularly T3 and T4, affect virtually every organ and tissue in the body. They control heart rate, body temperature and the rate at which cells convert energy. In the event of a shortage of these hormones, a condition known as hypothyroidism, all these processes slow down. The body functions, as it were, at a lower gear.

Besides direct fat storage, fluid retention also plays a role in the weight gain that people with hypothyroidism experience. Part of the extra pounds consists of fluid that accumulates in tissues, not exclusively of fat mass. This distinction is relevant for anyone understanding why the scales go up but the body fat percentage does not increase proportionally.

How much weight can you gain from an underactive thyroid?

Weight gain caused by an underactive thyroid is limited to a few kilograms in most people, typically between two and five kilos. A large part of this consists of fluid retention. Severe obesity is rarely caused solely by hypothyroidism. Anyone who has gained considerably more weight likely has other factors at play too.

This is an important point for people who are hoping that a thyroid diagnosis will be the explanation for dozens of kilos of excess weight. The slowing of the metabolism in hypothyroidism is real, but its scale is often overestimated in practice. Research into thyroid function and weight consistently shows that the effect on basal metabolic rate is relatively modest.

That does not alter the fact that the indirect effects of hypothyroidism, such as fatigue, reduced motivation to exercise and a changed diet, can indeed contribute to greater weight gain over a longer period. The thyroid therefore influences not only the metabolism directly, but also the behaviour that partly determines weight.

Which symptoms indicate an underactive thyroid besides weight gain?

In addition to weight gain, fatigue, feeling cold, dry skin, sluggish thinking and constipation are common symptoms of an underactive thyroid. A slower heart rate, hair loss and a depressed feeling may also occur. When several of these complaints are present at the same time, it is advisable to consult a doctor for a blood test.

The symptoms of hypothyroidism often develop gradually, leading people to initially attribute them to stress, a poor night's sleep or getting older. This makes the condition difficult to recognise without targeted diagnostics. A combination of complaints is more telling than a single symptom on its own.

Hair loss is a symptom that occurs in both hypothyroidism and other conditions. When hair loss is accompanied by fatigue, weight gain, and feeling cold, a thyroid investigation is a logical first step. However, hair loss as an isolated symptom also has other causes that are unrelated to the thyroid.

How is an underactive thyroid diagnosed?

An underactive thyroid is diagnosed via a blood test that measures the TSH level. TSH stands for thyroid-stimulating hormone and indicates how strongly the pituitary gland is stimulating the thyroid. An elevated TSH level indicates that the thyroid is not producing enough hormone. T3 and T4 levels may also be measured to provide a complete picture.

The GP is the appropriate person to request this blood test. Based on the symptoms and the test result, the doctor determines whether hypothyroidism is present and whether treatment is necessary. Subclinical hypothyroidism, in which the TSH is slightly elevated but hormone levels are still normal, does not always require immediate medicinal treatment.

Self-diagnosis based on symptoms is unreliable, because the symptoms of hypothyroidism overlap significantly with those of other conditions such as anaemia, sleep deprivation or depression. Only a doctor can make a diagnosis based on blood test results and determine the appropriate next steps.

Does thyroid medication also help with weight loss?

Thyroid medication is intended to correct a hormone deficiency, not to bring about weight loss. When hypothyroidism is treated and hormone levels normalise, the weight that was gained due to the condition may partially disappear. However, using thyroid medication as a slimming aid in people with normal thyroid function is medically unjustified and ineffective.

In practice, people being treated for hypothyroidism sometimes experience disappointment because their weight does not drop significantly after treatment. This is related to the previously described point: the weight gain caused by hypothyroidism is limited, and other factors contributing to excess weight are not addressed by thyroid medication.

Who still struggles with, after successful treatment for hypothyroidism, weight loss, is probably related to other causes of excess weight. Thyroid medication does not resolve those underlying factors.

What can you do if weight loss doesn't work despite a healthy thyroid?

When the thyroid functions normally but losing weight still fails, other factors are responsible. Insulin resistance, chronic stress, sleep deprivation, hormonal fluctuations and a calorie intake that is too high relative to expenditure are common causes. A medical assessment can help to determine which factors play a role and which approach is appropriate.

Lifestyle changes remain the foundation of any successful journey, but for some people, additional medical guidance is useful. GLP-1 medication is an example of a treatment that, following assessment by a doctor, can contribute to weight loss in people who are overweight or obese. Results vary per person and a doctor assesses whether such a course of treatment is medically appropriate.

It is also valuable to look at behavioural patterns that make weight loss more difficult. Irregular eating, a lack of physical activity due to a busy schedule and emotional eating are factors that are separate from the thyroid, but do indeed determine whether losing weight will be successful. A realistic picture of what a treatment can contribute, and what lifestyle must do, helps to set expectations properly.

How Wellumo helps when weight loss doesn't work

Wellumo offers medical guidance for people who struggle with weight loss and want to know whether a treatment is suitable for their situation. The programme is conducted entirely online and is supervised by Dutch-registered (BIG) doctors who independently assess whether a treatment is medically sound.

• Online medical intake via a questionnaire, assessed by a doctor within 24 hours on working days
• Support regarding GLP-1 medication for weight loss, following an individual assessment by a doctor
• Transparent pricing information beforehand, with no hidden costs
• Discrete shipping of medication following approval by a doctor and pharmacy
• Not everyone is eligible: the doctor decides on a person-by-person basis whether a treatment is appropriate

Do you want to know if a medically supervised programme is right for you? Read more about How Wellumo works or start immediately a Medical intake. Have you got any questions beforehand? If so, please do Contact us met Wellumo.