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What is meant by unexplained weight gain?
Unexplained weight gain means gaining weight despite not having made any changes to eating habits or physical activity. The weight gain may occur slowly or rapidly and is more often due to fluid retention than fat gain.
Why do people gain or lose weight?
Body weight is regulated by several systems that interact with each other: metabolism, hormones, the nervous system, sleep, stress levels, and fluid balance. Disturbances in these systems, even minor ones, can lead to changes in body weight.
Common causes of weight gain without an obvious reason
Hormonal changes
- Low metabolism (hypothyroidism): often causes fatigue, feeling cold, dry skin, and weight gain.
- Menopause: when estrogen levels decrease, this can lead to increased fat storage, especially around the abdomen.
- PCOS: hormonal imbalance can cause weight gain and difficulty losing weight.
- Elevated cortisol: long-term stress can affect appetite and the body’s ability to distribute fat.
Stress and lack of sleep
When we get too little sleep or are exposed to chronic stress, the hunger hormones leptin and ghrelin are affected. This can lead to increased appetite, sugar cravings, and reduced energy expenditure.
Medications
Certain types of medications can contribute to weight gain. Examples include antidepressants, corticosteroids, hormonal contraceptives, as well as some medications used to treat epilepsy and mental health conditions.
Fluid retention
Rapid weight gain is often due to the body retaining fluid, for example during major hormonal changes or in cases of heart or kidney impairment.
Insulin resistance
With insulin resistance, the body has difficulty regulating blood sugar levels, which can cause fat storage and weight gain despite having a normal diet and exercising.
When should you seek medical care?
Contact a healthcare provider if the weight gain occurs rapidly or without a clear explanation, if the weight cannot be influenced despite lifestyle changes, or if it affects your well-being or health. Also pay attention to other new symptoms, such as:
- Fatigue and lack of energy
- Swelling in the legs, face, or hands
- Feeling cold or heat intolerance
- Irregular periods or fertility problems
What can a blood test show?
A blood test can provide important information about, among other things, hormone status and metabolism. In cases of unexplained weight gain, it may be relevant to look at markers such as:
- TSH and free T4: provide information about thyroid function
- Blood glucose and HbA1c: may indicate insulin resistance and risk of diabetes
- Blood lipids: may be affected by changes in hormone levels and metabolism
- Cortisol: may increase during long-term stress.
- Sex hormones: when hormonal imbalance is suspected
When contacting healthcare services, blood tests are often combined with a clinical examination in which the physician reviews lifestyle factors and checks blood pressure, BMI, and waist circumference.
Treatment and self-care
The treatment initiated depends on the underlying cause. It may involve hormone therapy, adjustment of medications, or support related to stress, sleep, and lifestyle habits. Self-care is a major part of treatment and often includes regular sleep, a balanced diet, and stress management.
Related conditions
Unexplained weight gain may be associated with hypothyroidism, metabolic syndrome, PCOS, depression, and burnout syndrome.
