Can You Gain Weight In One Day?

Are you wondering how long it takes to gain weight? Can you gain weight in one day? This article will explore the answer to this question. 

Can You Gain Weight In a Day

If you’re trying to lose or gain weight, how long this takes will vary between people and is dependent on various different factors. It is possible, in some cases, to gain weight in one day.

Let’s have a look at why you might have gained weight in one day. 

Permanent Weight Gain After One Day 

It is very difficult to gain weight permanently after just one day. Even if you overeat by 500 calories, it would take you a week to gain 1 pound. Any weight that you gain within a day will not be very noticeable. 

Temporary Weight Gain After A Day 

If you often weigh yourself, you will sometimes notice that your weight has gone up overnight or within the day. While this can show an increase in weight, often this is an indication of weight fluctuation rather than weight gain.

This is more temporary than weight gain. Your body’s weight will fluctuate throughout the day. For instance, after you have eaten a large meal, you may weigh slightly more.

This can be because your body has not digested the food yet which can take a few hours.

You may also gain temporary weight due to excess fluid in your body. This is especially true if you eat foods that are high in salt because this retains fluids, increasing the number on the scale.

Fat Gain 

It is difficult to gain a significant amount of weight in just one day. It will take several weeks to gain weight that is noticeable. If you eat extra calories every day then you might add a pound to your weight by the end of the week.

What Causes Temporary Weight Gain?

There are a few things that can cause you to gain weight in a short period of time. This includes: 

  • Water retention due to a diet high in salt. 
  • Prescription medications such as antidepressants. 
  • An autoimmune condition. 
  • Menstrual cycle or falling pregnant. 
  • Stress.
  • Tiredness. 

The most common reason for weighing more throughout the day is water retention. This can occur when we eat a meal that is heavy in carbohydrates, or salt.

Tiredness is an interesting reason that you might gain weight overnight. It has been found that those who sleep more are less likely to be overweight than those who lack sleep.

Intense Workout 

An intense workout can cause your body to retain more water than usual, leading to you weighing more throughout the day. If you have been to a spin class, you may end up retaining lots of water afterwards.

This is because, when you exercise, you sweat. And when you sweat, you want to replace the lost fluids in your body, meaning you drink more water.

This can cause you to gain up to 5 pounds in one day, but it is not permanent weight. 


If you had a heavy night drinking alcohol in the evening, you may find that you will weigh more in the morning.

This is because, drinking alcohol means that you retain salt and water through osmosis because your body is looking for water to rehydrate your body. The water is drawn out of your bloodstream and into your tissues. 

As well as this, alcohol is often paired with salty snacks which will mean that you will retain even more fluids.

High Protein, Low Carb Diet

If you are following a high-protein diet, then you are likely consuming foods that contain lots of sodium. This causes water retention. If you’re following a diet like this, then you are likely to struggle from gaining weight overnight. 


Dehydration can cause your body to retain excess water because it is preparing for the lack of water. You can gain 5 pounds overnight in this way. If you rehydrate yourself, your body should regulate quite quickly and you should see the weight fall again. 

Food Intolerance Or Allergy

If you have a food intolerance, this can also lead to fluid retention. This is because it causes an inflammation in your gastrointestinal tract and the swelling leads to fluid retention.

Can You Gain Weight In One Day (2)

If you are intolerant to dairy, but you continue to eat it, this can cause bloating and fluid retention on a mass scale. 

Menstrual Cycle

Lots of women notice that they gain weight just before they start their period. This is due to bloating that is caused by your period. This water retention can be extreme for a lot of women.


Certain medications list bloating as their side effects. You can experience these side effects from antidepressants, birth control medication and lots of other medications.

Talk to your doctor if you think your medication may be causing this to see if there are any alternatives for you to try.

How To Weigh Yourself Accurately 

Stick To The Same Scale 

It is important to stick to the same scale everyday, and ensure that it is high quality. Different scales can show slightly different results so you should be careful of this.

There are some very high quality scales out there, so give these a go. 

Weigh Yourself At The Same Time Everyday 

It is very important to weigh yourself at the same time everyday. This is because your weight can fluctuate throughout the day due to retention of water and other factors.

The best time to weigh yourself is in the morning, as this is when you will have digested all of the food from the day before. You also don’t need to weigh yourself more than once a day, because the results will just become confusing and inaccurate. 

Final Thoughts 

You can gain weight in one day according to the scales, however this is mostly temporary weight that is caused by water retention and other factors listed above.

It is very difficult to gain a significant amount of weight in one day. Instead, this usually happens over a longer period of time.

Jenna Priestly

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