Unexplained Weight Gain: 9 Causes & What to Do

Unexplained weight gain can occur with hormonal changes, stress, medications in menopause. These processes affect metabolism and how the body stores fat. Eating foods that speed-up metabolism can help to reduce sudden weight gain. Read more about the fast metabolism diet and how to get started. 

If you notice rapid weight gain, even if you exercise regularly and maintain healthy eating habits, you should see a doctor for assessment. The doctor may assess the medications you are currently on, and determine whether the weight gain is related to a side effect. The doctor may also advise increasing your activity level with more physical exercise. 

Why am I gaining weight so fast?

The most common causes of unexplained weight gain are: 

1. Fluid retention

Fluid retention is characterized by the accumulation of fluid within cells which can lead to rapid weight gain. It can occur with 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 is a light massage that can be done manually or with specific equipment that stimulates lymphatic circulation and promotes retained fluid to enter the blood stream for elimination in the urine. It is still important, however, to see a doctor to identify the underlying cause of fluid retention and to seek treatment. 

Another way to reduce fluid retention is to take diuretic teas or diuretic medications. These should be taken as directed by a doctor, and incorporated in the a healthy, active lifestyle with 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. The body has more difficulty burning fat, leading to fat accumulation and weight gain.

Women, for example, experience menopause after the age of 40, which is associated with weight gain. Weight gain occurs due to a reduced production of female hormones, which leads to fluid retention and weight gain. 

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, the gynecologist may recommend hormonal replacement therapy to reduce the symptoms of menopause. 

3. Hormonal problems

Changes to hormone levels can lead to rapid, unexplained weight gain. This is seen with hypothyroidism, which is characterized by reduced production of T3 and T4 hormones. These hormones are needed for metabolism and provide energy for optimal functioning in the body. Reduce T3 and T4 levels can lead to reduced metabolism, excessive fatigue and fat accumulation, all which can lead to rapid weight gain. 

What to do: If you notice any symptoms of hypothyroidism, you should see a doctor for thyroid testing to ensure thyroid hormones are within normal levels. Treatment for these cases usually involve hormonal replacement medications, which are taken when fasting before breakfast, or as directed by an endocrinologist. 

4. Constipation

Constipation is characterized by decreased bowel movements, or bowel movements that are very hard and dry. It is one of the main causes of hemorrhoids.  Due to a lack of bowel movements, stool can start to build up, leading to a sensation of bloating and weight gain. 

If the constipation is persistent or if it accompanied by other symptoms, like bloody stools, mucus or hemorrhoids, it is important to consult a gastroenterologist. 

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

Prolonged use of certain medications can lead to weight gain. Corticosteroids, for example, are medications that are generally used to treat chronic inflammation, and constant use can alter the way fat is metabolized. It can lead to irregular distribution of fat throughout the body and weight gain, as well as reduced muscle mass and intestinal and stomach problems. 

What to do: Weight gain from medications varies from person to person, however you should see a doctor if you feel significantly uncomfortable. The doctor may assess the possibility of alternatives or discontinuing the medication. It is important to not stop taking the medication suddenly without discussing it with 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. 

Not sleeping well can also reduce the production of leptin, the hormone that helps with a full sensation. This can lead to overeating 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 day, avoid sleeping during the day and avoid screen time at least one hour before falling asleep. You can also take soothing and relaxing teas, like chamomile teas to help improve you sleep quality. Check out teas for insomnia that you can prepare at home. 

7. Stress, depression and anxiety

Stress and anxiety can cause tension that many people try to relieve through eating. Eating can provide pleasure and well-being, and can fill a void that can lead to weight gain. 

With depression, for example, people experience a reduced mood a interest in engaging in day-to-day activities, like exercise. Therefore, this population may look for happiness in sweets and other junk food which taste good. 

What to do: It is important to seek the help of a psychologist or psychiatrist to identify the underlying cause of anxiety, stress or depression. Treatment may vary from person to person, however many people benefit from identifying the underling trigger of their stress. Those who experience stress and anxiety should seek to practice activities that promote well-being, like reading, spending time with friends and participating in outdoor activities. 

8. Nutritional deficiency

One of the symptoms of a nutritional deficiency is excessive fatigue and reduced motivation to perform activities of daily living. Fatigue can remove any desire or reduce your mood in a way that you become more sedentary, leading to weight gain. 

A nutritional deficiency can occur as a result a low-nutrient diet, or due to a disease that interferes with normal nutrient absorption. 

What to do: In these cases, it is important to consider maintaining a healthy, 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 experience weight gain during pregnancy, as the baby grows in the uterus. Pregnancy requires a generalized increased in food intake to ensure adequate nutrition of both the mother and baby. 

What to do: Although weight gain during pregnancy is normal, it is important to pay attention to the type of food you are eating. Food that is low in nutrients can lead to gestational diabetes and high blood pressure, which can be life-threatening to both the mother and baby.  

Women are advised to be closley monitored during pregnancy, as this will help to reduce excessive weight gain and intake of low nutrient foods.