Unexplained weight gain can happen for many reasons, including hormonal changes, stress, insomnia, or certain medications. These factors can affect metabolism, how the body stores fat, and appetite control, leading to gradual or rapid increases in body weight.
This condition can also be related to natural life changes, like aging or menopause, or to medical problems such as hypothyroidism and fluid retention. Even when healthy eating and regular exercise are maintained, these factors can interfere with how the body burns energy.
Treatment for unexplained weight gain depends on its cause and may include dietary changes, hormone regulation, or increased physical activity. In some cases, addressing sleep problems, managing stress, or adjusting medications can help restore a healthy weight balance.
Why am I gaining weight so fast?
The most common causes of unexplained weight gain are:
1. Fluid retention
Fluid retention occurs when excess fluid builds up inside the body's cells, which can cause weight to increase rapidly. It can be triggered by a high salt diet, reduced fluid intake, and medication use. Many health problems can also lead to fluid retention, like heart disease, thyroid issues, renal disease and liver issues.
What to do: If you notice swelling, you can try to reduce it through lymphatic drainage. This gentle massage can be done by hand or with specialized equipment that stimulates lymphatic circulation, helping excess fluid move into the bloodstream for elimination through urine. However, it is still important to see a healthcare provider to determine the cause of the swelling and receive appropriate treatment.
Another way to reduce fluid retention is with natural diuretics or diuretic medications. These should be used only under medical guidance and combined with a healthy, active lifestyle and a low-salt diet. Learn more about other natural ways to get rid of fluid retention.
2. Age
Age is one of the main causes of unexplained weight gain, as it is normal for metabolism to slow down as we get older. As we age, the body has more difficulty burning fat, leading to fat accumulation and weight gain.
Women typically go through menopause some time after the age of 40, a stage often associated with weight gain. This happens because the decrease in female hormone production can cause fluid retention and an increase in body weight.
What to do: To reduce the effects of hormonal and metabolic changes from aging, it is important to maintain healthy habits, like being physically active and maintaining a balanced diet. In some cases, a gynecologist may recommend hormone replacement therapy to reduce the symptoms of menopause.
Read more about natural hormone replacement therapy.
3. Hormonal problems
Changes in hormone levels can cause rapid and unexplained weight gain. This often occurs in hypothyroidism, a condition marked by decreased production of the thyroid hormones T3 and T4.
These hormones regulate metabolism and supply energy for normal body function. When T3 and T4 levels are low, metabolism slows down, leading to fatigue, fat accumulation, and weight gain.
What to do: If you notice any symptoms of hypothyroidism, you should see a healthcare provider for thyroid testing to check whether your thyroid hormone levels are within the normal range. Treatment usually involves hormone replacement medication, which is taken on an empty stomach before breakfast or as directed by an endocrinologist.
4. Constipation
Constipation occurs when bowel movements become infrequent or when stools are hard and dry. It is one of the main causes of hemorrhoids. When stool remains in the intestines for too long, it can build up and cause bloating and a feeling of weight gain.
It is important to consult your primary care provider or a gastroenterologist if constipation is persistent or accompanied by other symptoms like bloody stools, mucus, or hemorrhoids.
What to do: Constipation occurs primarily due to a low fiber diet and lack of physical exercise. It is important to improve eating habits and to increase activity.
5. Medication use
Long-term use of certain medications can cause weight gain. Corticosteroids, which are commonly prescribed to treat chronic inflammation, can change how the body metabolizes fat when used continuously. This may result in uneven fat distribution, weight gain, loss of muscle mass, and digestive issues affecting the stomach and intestines.
What to do: Weight gain from medications varies from person to person, however you should see a healthcare provider if you are experiencing significant discomfort. The doctor may consider pausing the medication or switching to an alternative. However, it is important not to stop taking it suddenly without consulting your doctor first.
6. Insomnia
Insomnia is a sleep disorder characterized by difficulty falling or staying sleep. Prolonged insomnia from low melatonin production can lead to unexplained weight gain, as low melatonin levels can lead to reduced fat burning.
Poor sleep can reduce the production of leptin, the hormone that signals fullness, which may lead to increased appetite and weight gain.
What to do: One way to combat insomnia is to ensure optimal sleep hygiene. You should try to fall asleep at the same time every night, avoid sleeping during the day, and avoid screen time at least one hour before bed.
You can also try soothing and relaxing teas, like chamomile tea, to help improve sleep quality. Check out teas for insomnia that you can prepare at home.
7. Stress, depression, and anxiety
Stress and anxiety can create tension that many people try to ease by eating. Because eating provides comfort and a sense of well-being, it can temporarily fill an emotional void but may also lead to weight gain.
For example, people with depression often experience a low mood and lose interest in everyday activities such as exercise. As a result, they may seek comfort in sweets and other junk foods that provide a temporary sense of pleasure.
What to do: It is important to consult a mental health professional to help identify the underlying cause of anxiety, stress, or depression. Treatment can vary from person to person, but many people benefit from understanding what triggers their stress.
Engaging in activities that promote well-being, such as reading, spending time with friends, and enjoying outdoor activities, can also help reduce stress and anxiety.
Also recommended: Stress vs. Anxiety: Key Differences & How to Relieve Symptoms tuasaude.com/en/stress-vs-anxiety8. Nutritional deficiencies
One symptom of a nutritional deficiency is excessive fatigue and a lack of motivation to carry out daily activities. This persistent tiredness can lower mood and decrease the desire to be active, which may lead to a more sedentary lifestyle and weight gain.
A nutritional deficiency can occur as a result a low-nutrient diet or a disease that interferes with normal nutrient absorption.
What to do: It is important to maintain a healthy, well-balanced diet and to see a registered dietitian to formulate a diet that ensures all your health needs are met.
9. Pregnancy
It is normal to gain weight during pregnancy as the baby grows in the uterus. During this period, the body needs more food to provide enough nutrients for both the mother and the fetus.
What to do: Although weight gain during pregnancy is normal, it is important to pay attention to the type of food you are eating. A diet low in nutrients can increase the risk of gestational diabetes and high blood pressure, which may become dangerous for both the mother and the fetus.
Close follow up during pregnancy is recommended to help prevent excessive weight gain and discourage intake of low-nutrient foods.