Weight fluctuations: How our weight changes from day to day

Why our weight fluctuates?

It doesn’t matter, what goals we have on our “fitness journey”. Whether we want to lose weight, gain weight, or maintain it, the reality is, that the weighing scale will probably change from day to day even if we do everything according to our plan. I know, it can be really demotivating, when you are crushing your nutrition, working out, maybe you just want to lose few pounds and then you step on the scale and it says you gained two pounds from the day before. But I will tell you a secret: It is completely normal. But not only that. It would be more strange if your weight would consistently stay exactly the same in the maintaining phase or going down each and every day when you are trying to lose it.

Because when your weighing scale says you weigh more, it doesn’t necessarily mean that you gained FAT. And more to that, if you weigh two pounds more than yesterday, you can be pretty sure, it is not 2 pounds of fat. Why? We will talk about it in this article…

Reasons for Weight Fluctuations

There are many reasons why our weight is different every day. So before you try to change everything you are doing, try to think about these points and evaluate whether the truth is somewhere between them.

  1. Water Retention

Water retention is one of the most common reasons for weight fluctuations. And the fact that we weigh more if we retain water makes complete sense, as it is the same as holding a glass of water in our hands while weighing ourselves. The scale will just show the weight of the water on top of our weight. But what influences water retention? There are several variables:


Salt is a usual suspect when we are talking about water retention. Sodium binds water on its atoms so if we have a lot of it in our body, it will hold onto a bigger amount of water and it will stay this way until we have our sodium level that high. But you don’t have to worry about it. If you just ate more fast foods or salty foods one day, you can feel bloated the next day. However, as soon as the sodium leaves the body, the water flushes out as well.

Of course, it works the other way around as well. I mean, if you ate one day less salt that usually, your body will flush out even the water you retain day by day, and the day after you can weigh less. However, as soon as you come back to your ordinary amount of salt, the weight will most likely come back. So just keep an eye on that so you won’t be disappointed.


When eating carbs, the energy which is not IMMEDIATELY utilized will store in our body as glycogen which, similarly to sodium, holds onto water. One gram of carbs can bind three grams of water! What I mean by that is that if you eat a bag of salty chips, it is more than likely you will hold onto more water than usual (as it contains not only a lot of carbs but also a lot of salt).

But it doesn’t mean that you should avoid carbs! Not at all. Carbs are friends that will give you the energy that you most probably need in your day-to-day life. It is nothing to be afraid of. It is just of the variables you have to consider if you see sudden weight loss or weight gain.

Strength training

When lifting heavier weights, our muscles are being torn and for their regeneration and repair, our body needs a lot of nutrients – proteins, glycogen, water, and others. And that can for sure influence your weight the next day as well! So don’t worry if you weigh more after a heavy leg day, it is completely normal!

Menstrual cycle

Women are, in contrast to men, cyclical beings. And because of that, there are many things that change for women during one month. And it applies to water retention as well. The amount of water and time of the month when a woman retains it the most is individual of course. But from academic studies (performed on healthy women with regular menstrual cycles) there can be seen a tendency to retain more water on the first day of menstruation.


Stress is a common part of our everyday life. It is natural and what more, it is necessary. But if there is a lot of negative stress accumulated in our body, the level of a stress hormone – cortisol- will go up and it will contribute to water retention. It is very normal to retain water if you go through a more stressful period of your life. A lack of sleep can contribute to higher stress levels and therefore water retention as well.

 Just to avoid unnecessary misunderstandings, in this article, I am talking about the character of cortisol which will contribute to water retention. I am not talking about the possibility in which when someone is under a lot of stress in the long-term, they might consume more food due to stress eating and therefore create a caloric surplus. In that case, the gained weight doesn’t have to be just water, but that will show in a matter of weeks and months and not from one day to the next.

How can I influence water retention in my body? Well, some of those variables are completely out of our control and we can’t do anything about them and that is completely normal. But if you feel bloated all the time and you wish to change that a little bit, you can of course lower your salt consumption (but not rule out salt completely!), drink more water (as our body won’t hold onto extra water if it is not dehydrated) and last but not least to add some physical activity into our schedule. Sweating will of course flush out extra water (which also applies on days in which we generally sweat more, for example in the summer – we can weigh less the next day but we will regain that weight once we drink more) but it has been shown that people who have a sedentary lifestyle tend to retain more water than those, who have at least 30 minutes of light physical activity a day (for example a walk).

2. Amount of food and time of eating

We can eat the same amount of calories every day, but most probably the weight of the food itself will vary day to day. If we eat two pounds of vegetables one day, the weight of it will not simply just evaporate into the air, it will stay in our body. But once our body processes those foods, everything will go back to normal.

Time of eating has an effect on it as well. If we usually eat at 7 pm and weigh ourselves in the 7 am in the morning the next day, we give our body 12 hours to process that food. But if one day we decide to eat dinner at 10 pm and we weigh ourselves at 7 am in the morning the next day, we gave our body only 9 hours and it will not most probably process everything as we are used to. So don’t worry if you weigh a little more.

3.Time of weighing in

The same goes for the opposite. If we weigh ourselves sooner in the day than we usually do, it also can show a higher weight for the same reasons as eating later than usually

4. Bathroom visits

I think that is quite clear but if you usually go to the bathroom for number two every day and weigh yourselves after, the weight can be suddenly up if one day the bathroom visit is not ideal. The same goes for the period of bad digestion – you can simply weigh more because you are not sending out the usual package. In that case try to eat more fiber, drink a little extra water, and if it goes on for more days and it does not get better, visit a doctor!

Weight loss and weight fluctuation

The weight fluctuations are the most frustrating, I would say if someone is trying to lose weight and it just doesn’t goes the way they want. Things such as: “I am on a diet for a week and I gained two pounds” or “I was losing weight in the beginning but now my weight is staying the same for the whole week. I guess I will have to up my activity and lower my intake,” are commonly heard from the people who are trying to lose some weight.  But I will tell you that if you are trying to change your body and appearance in a way that is not just a new haircut, it will probably take a lot of time. More than you think, it is a very slow process. But if you are in a caloric deficit and you are CONSISTENT with it, don’t worry, the laws of thermodynamics apply to you as well and the results will come sooner or later.

Here I would like to demonstrate three patterns of weight loss according to Jordan Syatt. Maybe you will find yourself in one of those and it will assure you that you are not doing anything wrong. I would also add, that you will be able to observe those three patterns (more patterns exist, these ones are just the most common) only if you truly are in a caloric deficit and weigh yourself every day (if you weigh yourself every day, you will have more data for analysis).

People most usually think weight loss looks like this:

But the reality is unfortunately different. What three patterns do we therefore have:

  1. The weight goes down and up again…

In this pattern it is common that people are trying to follow some diet, some routine and the weight goes down, amazing! But suddenly it stops and it ups a bit, oh no. It is then common for those people to give up as soon as the weight goes even in a slightly opposite direction. Don’t give up, the results will come…

2. The weight stagnates, then it goes down, stagnates again, down again…

Here it is common for people to give up in the period of weight stagnation. There is not much more to say than just to keep on going.

3. The weight goes down, then up, and then stagnates. Again down, up, and stagnates…

I understand that it is difficult to watch your weight go up or stagnate while you are STILL in a calorie deficit, but it is very important to look at those processes from a long-term point of view!

Just to be clear, now I am not saying that your weight will DEFINITELY go according to one of those three patterns. All I am saying is that it is very probable if you keep an eye on your weight every day. So don’t worry if the weight goes up during your weight loss period. It is a PART of a process, it just can’t be deleted. If your weight goes down and down and down all the time, it is most probably not sustainable in a long term.

Maintaining phase and weight fluctuations

Even in the maintaining phase (e.g. a phase where we are not actively trying to lose or gain weight), it is completely normal to weigh differently every day. Here I would like to show my own experience. I am not trying to lose or gain weight at the moment and I eat every day roughly the same (and an amount that keeps me from calorie deficit or surplus) and my weight still changes everyday…

I weigh myself every day, and these are the fluctuations just in one week. And I wasn’t even on my period. My weight fluctuations up to 3 pounds in a week and no, I really don’t care if I weigh 2 pounds more than the day before. Why should I? It is completely normal. Our body is not a machine so we should not expect to act in this manner. By collecting data we can in time observe certain patterns in our own weight fluctuations and later we won’t be as surprised when we suddenly gain or lose weight.

When to be careful?

This article is concerned mainly with weight fluctuations from one pound up to five pounds. But if your weight jumps up and down 6,7,8 or more pounds and you have no idea why it is very important to discuss it with your doctor. It can be caused by excessive water retention which can be a sign of problems concerning the heart or kidneys, but that is only one of many possibilities. So don’t underestimate any BIG sudden changes in your weight.

To be aware of your own body

What should you take from this article? Whether you are trying to lose weight and you are in a calorie deficit or maybe you are maintaining your weight and your weight goes up and down or stagnates, it is more probable than not, that it is caused by one of the variables from this article.

It is good to know your body. I am not saying you have to weigh yourself every day and that it is ideal for everyone (especially for those of us who have the number on the scale connected to emotional reactions – in that case, it is wise to first work on that relationship, but we can discuss that some other day), but the more data you have about your body, the better you can observe how your body reacts to everyday occurrences and problems. It will help you to observe your body in a more objective manner and you will know what to expect from it.

Last but not least I would also say, that the best way of looking at your bodyweight is most probably in a manner of weekly and monthly “trends”. It doesn’t matter how your weight fluctuates from day to day, if it is going the direction you want it to go in a matter of weeks and months, you are doing great. If you want your results to stick, you have to accept the fact that the results won’t come tomorrow, I am sorry. So be patient, keep going, and don’t be too hard on yourself.


Nasim, H. “Effect of physical activity on body water in sedentary young
underweight and obese women”, African Journal of Educational Studies in Mathematics and Sciences, Vol. 8, 2010.

Smith, Amy. “How to lose water weight naturally”. Medical News Today. 2018. https://www.medicalnewstoday.com/articles/320603

White, C., Hitchcock, Ch., Vigna Y., Jerilynn Prior. “Fluid Retention over the Menstrual Cycle: 1-Year Data from the Prospective Ovulation Cohort”. Obstetrics and Gynecology International, 2011.

Water and its reaction with salt: https://www.usgs.gov/media/images/water-molecules-and-their-interaction-salt-molecules

1 Comment

  1. […] that it is better to weigh yourself every day at the same time exactly BECAUSE there are those fluctuations. If you observe how your body works, it is then that much easier to say what is happening with it, […]

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