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Why does my weight fluctuate so much? Understanding the reasons behind fluctuations

December 27, 2023
5 minutes
Lifestyle Health & Wellness
Wellness mythbusting

When you’ve been focused on healthy changes to your diet and lifestyle, stepping on a scale to see an unexpected increase or decrease can be disheartening, to say the least. Yet weight fluctuations are actually quite common, even when you’re choosing healthy foods and movement. If you’re seeing weight fluctuations, even unexpected increases or decreases in your weight, don’t be alarmed. This is something everyone experiences, and here are some of the reasons why it happens.

Common causes of weight fluctuations

Is weight fluctuation normal? Yes, it is, and everyone experiences it. So what causes the weight to go up or down on the scale, even when you’re focused on making healthy changes to achieve your weight goals? Here are some common causes of weight increases:

  • Foods, especially foods high in sodium or carbs
  • Hormonal changes, especially menstruation
  • Medications you take
  • Alcohol consumption
  • Lack of a bowel movement

Here are some common causes of drops in your weight:

  • Exercise and sweat
  • Hormonal changes
  • Stress
  • Recent urination or bowel movement

Daily and weekly weight variations

How much does weight fluctuate throughout the day or week? Weight variations happen both on a daily basis and a weekly basis. In a healthy adult, it’s common for weight to fluctuate as much as five to six pounds a day and even more after eating a meal. For this reason, you might want to try to weigh yourself at the same time each day.

Yet even day to day, you can experience weight fluctuations, even when all other factors are similar each day and you’re weighing at the same time of day. According to Henry Ford Health, the average healthy adult will gain or lose two to eight pounds every few days, and that’s not due to fat loss but rather normal weight fluctuations. In addition, weight tends to be higher at the beginning of the week for most people, and lower toward the end of the week.

Water weight and hormonal influences

One of the reasons your weight will change over the course of a week is due to hormones, which can cause you to retain, or sometimes to lose, water weight. Hormone changes, especially in people who are assigned female at birth, are a common reason for weight gain. When a woman is nearing her menstrual period, she often retains water and gains weight, and that weight comes off after her cycle. How much do you gain on your period? This varies from person to person and may depend on how much unhealthy food you consume, but increases of between 1 and 5 pounds are common over that week.

In contrast, you can also lose water weight which can cause a drop in weight. Going on a run on a hot summer day may make you lose water weight as you sweat. These types of weight gains or losses aren’t directly related to fat gain or loss, and as such, are temporary in nature.

Dietary factors: how food choices impact temporary weight changes

Hormones are just one reason people might gain water weight. Your dietary choices also impact your weight. Remember, all food has weight, so you’re going to weigh more after eating than before, but some foods can carry over long after the meal and cause temporary increases in your weight.

For example, if you eat a large amount of salty or processed foods in a day, you might retain more water over the next few days as your body works to flush out the salt and processed chemicals. Large meals, such as a holiday feast, can also cause temporary weight increases until your body processes all of the food.

Foods high in carbohydrates may also lead to water retention, which leads to increases in weight. This is why you might notice temporary weight gain after you eat out or after several holiday parties full of sweet treats. Restaurant foods, even healthier choices at restaurants, tend to be higher in salt and processed chemicals than foods you make at home, and as such, they’ll create a temporary increase in weight.

Sometimes, people are surprised to know that not drinking enough water can actually cause you to gain weight temporarily. Your body will retain more water when you aren’t drinking enough, and this, in turn, can lead to temporary weight gain.

What and how often you eat can also cause weight decreases. Periods of fasting, including overnight when you’re sleeping, will cause your weight to decrease temporarily. Similarly, if you eat a high protein, low carb diet for a while, you may see the scale moving down, but adding in healthy carbs can help it balance back out.

How should you weigh yourself? Long-term trends vs. short-term changes and what to focus on

These temporary changes in weight can be discouraging for many people who are trying to make healthy changes, but they’re a normal part of being human. One way to counteract the disappointment at seeing that number go up (or down, if you’re trying to gain weight) is to weigh yourself in the best way.

First, try to weigh yourself at the same time each day, preferably without shoes on. Wear similar clothing each time you weigh, and, if possible, weigh after using the restroom. Many people find it convenient to weigh after they get up in the morning before eating breakfast.

After learning to weigh yourself well, consider looking at long-term trends rather than short-term fluctuations, recommends Very Well Fit. If you’re seeing the scale increase day after day, with no drops, it may be time to consider making a change. However, if you’re seeing gradual decreases, with occasional increases, and your goal is to lose weight, then you’re succeeding. Those increases are likely due to normal, natural causes.

Another option to consider is using a body weight scale that measures more than just pounds. These scales will measure your body fat and water percentage to help you see where you stand in your health goals. If you’re adding healthy exercise to a change in your diet, this will help you know if your weight increases are due to increasing muscle mass, which might be part of your goal, rather than increases in body fat.

You can also use another measure to weigh your success instead of your weight. For example, rather than jumping on the scale, see how your clothes fit. If they're getting a little tight consistently, and your goal isn’t to gain, then you’ll want to reevaluate your changes, but if they're getting looser, you might be on the right track toward your healthy living goals.

You can also use a tool, such as Evidation, to track your health goals, including exercise and food choices, and earn rewards for the positive changes you make. Remember, wellness is about more than just weight, and using a health tracker and pairing it with Evidation can help you take your next steps towards healthy living so that you can focus less on normal weight fluctuations and more on your healthy lifestyle progress. Track your health with Evidation today.

Wellness mythbusting
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