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What causes weight gain in women? Related conditions and treatments

Weight gain is a common symptom in women and may be caused by PCOS, hypothyroidism, menopause, or high cortisol
Leandra Beabout
By | Updated on Sep. 18, 2025 Medically reviewed by Leslie Greenberg, MD
Female gender symptom made of pink pills: What causes weight gain in women?

Key takeaways

  • Weight gain is a common symptom in women that may be caused by lifestyle changes, age-related hormone changes, underlying health conditions, or certain medications.

  • Typically, weight gain in women does not require immediate medical attention.

  • Weight gain in women does not always require treatment. It may resolve with lifestyle changes within weeks or months, depending on the degree of weight gain.

  • Treatment of weight gain in women varies by cause. Read more about treatments for PCOS, hypothyroidism, and menopause here.

  • Weight gain in women can sometimes be managed with a weight-loss diet, regular exercise, and healthy stress management.

In this article:

Overview: What does weight gain in women look like?

Weight gain in women is often linked to lifestyle, hormonal changes, or both. Sometimes, it involves an increase in overall body mass, but sometimes, it presents more like a sudden or gradual increase in belly fat. Weight gain in women may also be accompanied by related symptoms such as bloating or loss of muscle mass. 

If you are a female who has noticed unexplained weight gain, it’s essential to know that multiple factors can contribute to a higher number on the scale. Below, learn more about the most common causes of weight gain in women.

What causes weight gain in women?

Several factors contribute to weight gain in women. These include lifestyle influences like diet and exercise, medical conditions, and certain medications. 

Calorie surplus

When people consume more calories than they burn, their body mass increases. That’s why some of the most common causes of weight gain in any population are related to diet, exercise, or both.

Research shows that ultra-processed diets tend to cause excess calorie intake, which leads to weight gain. Some of the most high-calorie foods are processed foods, including refined carbohydrates, high-sugar foods, and foods full of saturated fat. Conversely, too little exercise can cause weight gain because calories are consumed at a higher rate than burned. 

Hypothyroidism

Hypothyroidism, or an underactive thyroid gland, affects 4.6% of Americans ages 12 and older. It is more common in females than males. Not all women with hypothyroidism experience body weight changes, but weight gain is one of the most common symptoms, according to JaLorean Hayes MPH, BSN, registered nurse and founder of Meal Maps. 

“The thyroid gland regulates metabolism, and when it underperforms, the body slows down, leading to weight gain,” explains Barbara Sparacino, MD, a triple board-certified physician and founder of The Aging Parent Coach. 

Polycystic ovary syndrome (PCOS)

Polycystic ovary syndrome (PCOS) is a hormonal disorder that affects up to 10% of women of reproductive age. The hormone imbalances associated with PCOS also cause insulin resistance, which is strongly associated with weight gain in adults and increased risk of Type 2 diabetes.

“Many women with PCOS struggle with weight gain, especially in the abdomen,” says Jennifer Nicole Bianchini, RD, IFNCP, a registered dietitian and functional nutrition practitioner. “However, not all women will gain weight or experience difficulty losing weight … Some forms of PCOS are not directly associated with insulin resistance or inflammation.”

Bottom line: Women with PCOS often gain weight easily — and struggle to lose weight when needed. However, seeking personalized treatment for your PCOS type can help with weight management.

Perimenopause and menopause

Dr. Sparacino and Bianchini say that the hormonal shifts associated with perimenopause and menopause can cause body composition changes. Sometimes, those changes include weight gain or difficulty losing weight.

“Estrogen plays a role in weight distribution,” explains Dr. Sparacino. “As [estrogen] levels decline with age, women may notice weight shifting to the midsection. Bianchini says some women report body fat shifting from their hips and thighs to their bellies. “Even women who are not experiencing lifestyle or diet changes can experience unintentional weight gain due to these hormonal shifts.”

Anyone experiencing significant weight gain during menopause should seek personalized medical advice from their primary healthcare provider or gynecologist. Some body composition changes can be treated with diet and exercise, but some might require nutritional supplements, prescription drugs, or hormone therapy. 

High cortisol

Cortisol is a naturally occurring hormone often dubbed ‘the stress hormone.’ However, cortisol also regulates metabolism and immune response. According to Bianchini, when a woman is chronically stressed, her cortisol levels can stay elevated, triggering a cascade of hunger cravings, elevated blood sugar, insulin resistance, and fat storage.

Another rare but possible cause of high cortisol? Cushing’s syndrome, a condition “caused by excess cortisol production, often due to prolonged steroid use or adrenal gland dysfunction,” says Dr. Sparacino. “[Cushing’s syndrome] can cause rapid weight gain, especially in the face, upper back, and abdomen.” 

Ultimately, high cortisol levels can increase several risk factors for obesity and overweight. Any woman concerned that stress is leading to weight gain should consider stress reduction strategies (yoga and biofeedback) and consult her healthcare provider about lab testing and lifestyle changes that might improve her ability to manage stress.

Metabolic syndrome

Metabolic syndrome is closely linked to abdominal weight gain. In fact, belly fat is a symptom of metabolic syndrome, and metabolic syndrome can increase belly fat.

Metabolic syndrome is an umbrella term for a group of conditions that raise your risk of heart disease, diabetes, and stroke, according to the National Institutes of Health (NIH). The conditions include high blood pressure, high blood sugar, and unhealthy cholesterol levels (high triglycerides and low HDL). “The combination of these conditions promotes fat accumulation,” explains Bianchini.

Some women with metabolic syndrome find it challenging to lose weight — but the good news is that with the right lifestyle changes, metabolism syndrome is reversible, according to UCLA Health.

Medications

“Certain medications… can lead to weight gain by altering metabolism, increasing appetite, or causing fluid retention,” says Dr. Sparacino. “The degree of weight gain varies by individual and medication type.”

Some medications that cause weight gain include:

Medication-related weight gain in women is not uncommon. If weight gain is an unwanted side effect of one of your current medications, talk to your prescriber about switching to an alternative prescription drug.

Should I be worried about female weight gain?

Weight gain in women is common. However, it’s a good idea to seek medical advice from your healthcare provider if weight gain is “unexpected, rapid, or accompanied by other symptoms like fatigue, hair thinning, irregular periods, or swelling,” says Dr. Sparacino. She also says it’s important to schedule a medical evaluation if a healthier diet or increased physical activity doesn’t lower the number on the scale. In these cases, weight gain in women could indicate an underlying hormonal or metabolic issue.

Left unchecked, excessive weight gain can lead to obesity (a body mass index over 30) or being overweight (BMI of 25-30), which can then lead to other health complications, such as high blood pressure, sleep apnea, joint pain, Type 2 diabetes, and mental health issues such as depression or poor body image, according to Dr. Sparacino.

How is the cause of weight gain in women diagnosed?

In many cases, weight gain can be self-diagnosed. For instance, weight gain can often be traced to a calorie surplus due to reduced physical activity or increased intake of sugar, fat, processed foods, or alcohol. 

However, a healthcare provider might investigate possible underlying health conditions if weight gain is rapid, unexplained, or accompanied by other symptoms. In that case, patients are usually diagnosed through a physical examination, discussion about medical history and lifestyle, and diagnostic tests. Dr. Sparacino says a physician might order tests such as:

  • A thyroid panel (TSH, T3, and free T4) to check for hypothyroidism
  • A fasting blood sugar test to assess for prediabetes or diabetes
  • A lipid panel to evaluate cholesterol levels and metabolic health
  • A complete metabolic panel (CMP) to test kidney, liver, and electrolyte function
  • And rarely tested are hormone levels (testosterone, estrogen, progesterone, and cortisol) to check for PCOS or menopause-related imbalances

How to stop weight gain

How to treat weight gain in women or how to get rid of weight gain in women depends on the underlying cause. For instance, someone who has been consuming processed food and sweetened lattes every day can probably reduce their weight simply by changing their habits. However, serious lifestyle changes or medication may be necessary in other cases.

Weight gain in women treatments include but are not limited to the following:

Most importantly, know when to consult your healthcare provider

Causes of weight gain in women may include lifestyle changes, aging, or conditions that affect hormone levels. This may resolve on its own without treatment. However, if weight gain in women continues, worsens, or is accompanied by fatigue, hair thinning, irregular periods, or swelling, it could be a sign of hypothyroidism, high cortisol, or a hormone imbalance and require medication. Only your healthcare provider can rule out infection or other serious health conditions. Visit your doctor to determine the best treatment for weight gain in women.

What’s next? Additional resources for people with weight gain in women

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