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10 reasons why you have gained weight overnight

Overnight weight gain can be very disappointing especially if you are trying your best to stick to your fitness regime. Here's probably why it is happening to you.
Written by: Aayushi Gupta
Updated On: 19 Mar 2025, 02:31 pm IST
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Overnight weight gain usually resolves itself in a few days. Image courtesy: Freepik

We all know the dreadful feeling of looking at weight gain on the scale. What’s worse is when you seem to have gained this weight overnight. There might be times when you are eating healthy, working out well, yet your weighing scale indicates that have gained weight. While overnight weight gain is scary, it is quite common and can happen to anyone. It’s absolutely possible to gain one to two kgs overnight! But relax, it’s not fat and it’s totally temporary. It can be as simple as being bloated, lack of sleep or just stress. Check out why you might have gained weight overnight and how to stop it.

Is overnight weight gain normal?

Yes, it is possible to gain weight over night. Laparoscopic and Bariatric Surgeon Dr Aparna Govil Bhasker explains that once the cause of this overnight weight gain is determined, it can be tackled with. “It is common to see a fluctuation of one or two kgs while working hard to lose weight. The good news is that it can be tackled by learning about the causes of this kind of fluctuation and following healthy practices consistently.”

A woman with a weighing scale
Dehydration can cause overnight weight gain. Image courtesy: Freepik

Common causes of overnight weight gain

If you are experiencing overnight weight gain, check for these factors.

1. Crash dieting

Transitioning from a very low calorie and low carbohydrate diet to a low calorie and moderate carbohydrate diet often leads to overnight weight gain of 1-2 kgs. This is mainly because of a sudden increase in the carbohydrate content which is stored along with water in the body.

2. Stress

We all get stressed some more than others, and some manage it differently to others. But at some point, we’ve all been stressed about something but stress over a longer time period can cause cortisol to increase and this hormone will work in tandem with water and this cause fluid retention and water weight. This can also lead to overnight weight gain.

Also, read: Holiday weight gain is common. Here’s how you can reverse it

3. Lack of sleep

Lack of sleep is another reason behind overnight weight gain. Staying awake until late can be a factor that can cause weight gain. Insufficient sleep can make you eat more and lead to poor circadian rhythm. While sleep won’t help you lose weight, not getting enough of it will probably make you gain weight. So focus on getting quantity sleep about 7-8 hours a night.

4. High sodium intake

Sodium causes you to retain a large volume of water and weigh heavier on the scale the next morning. This is also why you might be experiencing overnight weight gain. This is because the body needs to keep its sodium to water ratio balanced to function properly, so will hold on to water if too much salt is consumed.

5. Alcohol consumption

Excessive alcohol consumption leads to increased calorie intake, especially when consumed with sugary mixers. Alcohol consumption dehydrates the body and compels it to hold on to water leading to water retention. In addition, it could lead to overnight weight gain due to bloating by causing irritation to the gastrointestinal tract

6. Intense workout

You did an intense workout the day before. A new exercise regimen puts stress on your muscle fibres and can lead to overnight weight gain. This causes small micro tears, also known as micro trauma, and some inflammation. Those two conditions in your muscle fibers are the reason you may gain some weight.

7. Premenstrual syndrome (PMS)

Premenstrual syndrome (PMS) is another cause for overnight weight gain. It can lead to an increase in water weight. Some women may also have an urge to eat salty foods during periods and that can lead to water retention. Once your periods start, the hormones normalise again, and the weight comes back to normal.

it's very common to gain weight after a crash diet
On the days of aunt flo payed a visit, you can gain weight. Image courtesy: Shutterstock

8. Timings

If you are experiencing overnight weight gain, then check the timings of your meals, especially your dinner. Either you had a late meal last night or you may have checked your weight at a different time the day after.

Also, read: Want swift but safe weight gain? Avoid making these mistakes first

9. Certain medications

Yes, there are certain medications too that can lead to overnight weight gain. Some medications can lead to water retention, induce lethargy, or can cause an increase in appetite all of which contribute to weight fluctuations.

10. Poop

It is very important to understand when is the right time to weigh yourself. Standing on the weighing scale at the wrong time can also indicate overnight weight gain. If you weigh yourself before having your bowel movement, you are likely to see weight fluctuations.

If you find yourself freaking out about the number on the scale, just know that the number on the scale does not define who you are. Your body can fluctuate in weight every single day. It’s not pure fat. You can’t gain a whole lot of weight overnight. That’s unrealistic! Just keep focusing on that calorie deficit, high protein, activity, and sleep. You got this!⁣

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Related FAQs

How much weight can you gain overnight?

It is not possible to gain more than one kg of weight overnight. This is usually due to bloating or water retention, and goes away.

How to lose overnight weight gain?

Try to drink some water, hydration can help you get rid of bloating. Getting in some light exercise can also help.

Disclaimer: At Health Shots, we are committed to providing accurate, reliable, and authentic information to support your health and well-being. However, the content on this website is intended solely for informational purposes and should not be considered a substitute for professional medical advice, diagnosis, or treatment. Always consult a qualified healthcare provider for personalised advice regarding your specific medical condition or concerns.

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About The Author
Aayushi Gupta
Aayushi Gupta

Aayushi Gupta is a health writer with a special interest in trends related to diet, fitness, beauty and intimate health. With around 2 years of experience in the wellness industry, she is connected to leading experts and doctors to provide our readers with factually correct information.

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