Weight gain that seems unexplainable or weight gain alongside other symptoms could be due to an underlying health condition.
A medical professional could help you identify or rule out diseases linked to weight increases and recommend treatment if needed.
This article details some conditions that can cause weight gain, including how they may affect weight, their symptoms, and what to do.
Hypothyroidism, or an underactive thyroid gland, occurs when your body doesn’t produce enough thyroid hormones. Some people may experience weight gain if they have an underactive thyroid gland.
With hypothyroidism, weight gain is the result of a buildup of excess salt and water instead of body fat, experts say.
Other symptoms of hypothyroidism include:
- fatigue
- increased sensitivity to cold
- joint or muscle pain
- dry skin or hair
- irregular or heavy periods
- fertility problems
- slow heart rate
- depression
Learn more about the symptoms, diagnosis, and treatment of hypothyroidism.
Cushing syndrome occurs when you have too much of a hormone called cortisol.
Weight gain and increased body fat are some of the primary symptoms of Cushing syndrome, often appearing as:
- increased fat around the stomach and chest
- a buildup of fat on the back of the neck and shoulders that may resemble a hump
- puffiness, roundness, or discoloration of the face
Other symptoms of Cushing syndrome include:
- easy bruising
- large, discolored stretch marks
- weakness in the arms or thighs
- reduced sex drive
- fertility problems
- depression or mood changes
Read more about Cushing’s syndrome symptoms and treatment.
Menopause may increase the likelihood of weight gain, according to a 2019 review. Reasons for this may include:
- hormonal changes
- aging
- psychological symptoms, which may increase emotional eating or changes in dietary habits
- possible decreases in physical activity due to aging or menopause symptoms
Signs of menopause include:
- irregular or skipped periods
- hot flashes
- difficulty sleeping
- urinary incontinence
- mood changes, depression, or anxiety
- reduced sex drive
See more about menopause symptoms and management.
Polycystic ovary syndrome (PCOS)
PCOS, which affects how the ovaries work, can cause weight gain due to insulin resistance, whereby the body doesn’t respond effectively to insulin. The hormone insulin helps manage blood sugar levels.
Other symptoms of PCOS include:
- irregular or absent periods
- difficulty getting pregnant
- excessive hair growth, such as on the face, back, chest, or buttocks
- hair loss or thinning on the head
- oily skin
- acne
Read more about PCOS, including its treatment and diagnosis.
Weight gain may occur due to insulin resistance.
Insulin resistance is when your body doesn’t respond well to the hormone insulin, which helps control blood sugar levels. Insulin resistance increases your risk of developing diabetes. Insulin medication to help treat diabetes may also contribute to weight increases.
Insulin resistance doesn’t usually have symptoms. However, if you have diabetes, you may experience:
- frequent urination
- excessive thirst
- increased hunger
- blurry vision
- numb or tingling hand or feets
- fatigue
- dry skin
- slow-healing sores
- frequent infections
See more about insulin resistance and diabetes.
Metabolic syndrome is a set of conditions that can increase your risk for heart disease. The risk factors include:
- high blood pressure
- high blood triglycerides and low-density lipoprotein or “bad” cholesterol
- low high-density lipoprotein or “good” cholesterol
- high blood sugar
- abdominal obesity
The symptoms you experience depend on the condition, such as increased thirst due to diabetes.
Learn more about the signs and diagnosis of high blood pressure, high cholesterol, and high blood sugar.
Edema is a buildup of fluid that often occurs in the legs, ankles, and feet. This leads to weight gain due to swelling and fluid retention rather than excess body fat.
Edema can be caused by:
- injury
- insect bites or stings
- kidney, liver, or heart disease
- blood clots
- infection
- eating too much salt
- pregnancy
- some medications
- overweight
- sitting or standing in the same position for a long time
Edema symptoms include:
- swelling
- stretched, puffy, or shiny skin
- skin that pits or dimples when pressed and holds the indent after removing pressure
- a feeling of heaviness
Learn more about edema causes and treatment.
Heart failure can lead to rapid weight gain. This weight gain is often due to edema rather than excess body fat.
Symptoms of heart failure can include:
- shortness of breath
- fatigue
- racing heart rate
- swelling, which often occurs in the legs or feet
- confusion or changes in mental status
Contact a doctor as soon as possible for any rapid weight gain or other symptoms of heart failure.
Read more about heart failure.
Much like heart failure, kidney disease can cause the appearance of weight gain due to edema.
Kidney disease symptoms, including edema, usually occur at later stages. Other symptoms include:
- weight loss due to decreased appetite
- shortness of breath
- fatigue
- blood in the urine
- frequent urination
- difficulty sleeping
- itchy skin
- muscle cramps
- nausea
- headaches
- erectile dysfunction
Learn more about kidney disease symptoms, causes, and treatment.
Adult growth hormone deficiency (AGHD)
AGHD occurs when the pituitary gland does not produce enough growth hormone. It can lead to weight gain, excess fat around the belly, and numerous other symptoms, including:
- fatigue
- heat sensitivity
- lack of muscle tone or difficulty building muscle
- cognitive impairments, such as lack of focus, disorganization, and difficulty remembering information
- depression
Read more about AGHD, including its symptoms and treatment.
Other conditions that may cause weight gain
Other conditions that may contribute to weight gain in some cases include:
Other conditions may also increase some risk factors for weight changes, leading to weight gain. For example, asthma may make it difficult to be physically active, increasing the likelihood of excess weight.
Some medications for health conditions may also lead to weight gain, such as some steroids and antidepressants.
Contact a healthcare professional if you have concerns about weight changes. Also, talk with a doctor for new, persistent, or concerning symptoms. If needed, they can recommend treatment.
Weight gain is often connected to lifestyle changes and not a health condition. In such cases, excess weight can typically be treated with regular physical activity and following a diet as recommended by a doctor.
Read more about the causes and treatment of excess body weight.
Health conditions that that may contribute to weight gain include:
- insulin resistance
- Cushing disease
- hypothyroidism
- menopause
- polycystic ovary syndrome (PCOS)
- metabolic syndrome
Other conditions, such as heart failure and kidney disease, may also cause weight loss due to fluid retention.
Talk with a healthcare professional if you experience unexplained weight gain or have other symptoms alongside weight gain.