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Possible Causes of Sudden Weight Gain: When Should You Worry?

Expertly reviewed by Chris Icamen · Dietetics and Nutrition

Written by Tracey Romero · Updated Feb 14, 2022

Possible Causes of Sudden Weight Gain: When Should You Worry?

Weight changes are normal in many points in life. Our growth and development — especially during puberty and middle age — cause our weight to fluctuate throughout the years. Even over the span of a day, our weight fluctuates because of how we eat and how we go about our daily lives. In this article, we explore the possible causes of sudden weight gain and explore other symptoms of diseases that are usually linked to it.

Possible Causes of Sudden Weight Gain

Oftentimes, we worry or fixate on our weight gain (or loss) especially if it’s unintentional, and sometimes we don’t notice it. As the months pass, when we see our photos side-by-side, we feel like these changes are sudden. However, this is no cause for alarm unless you’ve lost or gained at least 15% of your body weight in a month.

Here are some possible causes of sudden weight gain.

1. Acromegaly

Acromegaly is a hormonal condition linked to the pituitary gland, which is in charge of producing the growth hormone. This is one of the possible causes of sudden weight gain because when the pituitary gland produces too much of it, which could happen in middle adulthood, you may experience the enlargement of feet, hands, lips, tongue, or nose.

Other symptoms include aching joints, a deepening voice, excessive sweating, sleep apnea, and skin tags.

2. Cirrhosis

Cirrhosis is when healthy liver tissue is replaced by scar tissue. This causes sudden and drastic weight gain often in the abdomen area, which could appear enlarged. This is because the fluid builds up within the abdominal cavity.

Other symptoms include abdominal pain, swollen ankles, and shortness of breath.

3. Cushing Syndrome

Another possible cause is a rare disease called Cushing Syndrome, involving high levels of the hormone, cortisol. This disease develops as a result of a tumor or long-term steroid treatments. Oftentimes, the weight gain is focused on the chest, face, stomach, or upper back, while keeping the arms and legs thin, depending on the cause.

Other symptoms include erectile dysfunction, fatigue, irregular menstrual cycle, and muscle weakness. Oftentimes, this is triggered by glucosteroids, which is a common treatment for rheumatoid arthritis and systemic lupus erythematosus.

4. Fluid Retention

One of the ways that our body weight fluctuates over the span of even just a day is fluid retention. However, these fluctuations could get a bit more drastic if you’re suffering from premenstrual syndrome, standing for long periods of time, or experiencing swelling in some part of your body.

This could also be caused by more complex conditions like organ failure and kidney problems. If any change is too drastic and too immediate, make sure to contact your doctor immediately.

5. Hypothyroidism

The thyroid produces hormones that deal with metabolism. This means that when you have an underactive thyroid or hypothyroidism, your thyroid is not producing enough hormones. This causes your metabolism to slow down, resulting in you gaining weight.  

Anyone can be diagnosed with hypothyroidism at any age but this is most common in older women. Other symptoms include constipation, fatigue, feeling cold, having dry or brittle skin, hair, and nails, or stiff joints.

6. Steroid Treatment

If your doctor has recently prescribed corticosteroids for diseases like asthma and arthritis, it’s possible that your steroid treatment is behind the sudden weight gain. 

Corticosteroids can increase your appetite. And eating more will suddenly put you at a surplus of calories, which leads to weight gain. Make sure to seek out the guidance of your doctor to help maintain your weight through your treatment plan.

7. Stress

The hormone attributed to stress is cortisol and this hormone triggers the release or the production of insulin. Insulin then works to increase your appetite, which explains why stress eating is a common response to high cortisol levels. This often makes you eat more calories than you need, which causes weight gain and it could be sudden if you’re stressed and snacking for a prolonged period of time.

8. Insomnia

Research has shown that insomnia is linked to sudden weight gain. This is because sleep-deprived people often eat more carbohydrates over the day as a source of energy due to the lack of rest. Over a period of time, this could make for pretty drastic weight gain if left unchecked and untreated.

9. Quitting Smoking

Nicotine, present in cigarettes, is an appetite suppressant. Hence, quitting can cause a drastic increase in appetite which leads to weight gain. Additionally, withdrawal symptoms include stress which also leads to overeating.

Possible causes of sudden weight gain

Key Takeaways

Now that we’ve run through a number of possible causes of sudden weight gain, it’s important that we remind you to get professional medical insight if this has happened to you or someone you know, especially if the weight gain occurs at a drastic scale or an alarming rate.

Learn Other Healthy Eating Tips here


Hello Health Group does not provide medical advice, diagnosis or treatment.

Expertly reviewed by

Chris Icamen

Dietetics and Nutrition

Written by Tracey Romero · Updated Feb 14, 2022

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