Tracking your weight long-term can help you determine if you’re on track with your weight management goals. However, it’s normal for the number on the scale to fluctuate by about 0.57-3.2 pounds from one day to the next. Here are some factors that can explain why.
When you choose to weigh yourself matters. Your body weight naturally fluctuates throughout the day due to changes in food intake, hydration, bowel movements, and even sweat loss.
You can account for some of these changes by weighing yourself at the same time each day. For example, make a habit of stepping on the scale in the morning after you’ve used the bathroom and before you’ve had breakfast.
What you’ve eaten in a day can significantly influence short-term fluctuations in weight. Foods higher in carbohydrates or sodium can cause your body to retain water, which could lead to a temporary increase in weight.
Day-to-day weight fluctuations caused by what you’ve eaten typically add temporary mass to your body until they are digested and excreted and don’t typically reflect changes in body fat.
Hydration levels play a large role in short-term weight changes, as water makes up between 45-75% of our body mass.
Some people might have lower amounts of fluids in their body if they’re dehydrated or sweat excessively, so their weight may be slightly lower. On the other hand, consuming more sodium or exercising infrequently may lead to fluid retention and temporary increases in weight—particularly if you’re drinking more water.
In these cases, weight is changing due to the amount of water in your body, not because body fat has changed.
Hormonal changes can influence daily weight fluctuations by affecting fluid retention, appetite, and even metabolism.
For example, during the menstrual cycle, fluctuations in estrogen and progesterone can lead to short-term fluid and sodium retention, temporarily increasing body weight.
In addition, stress-related hormones like cortisol can have an effect on eating patterns. Cortisol also plays a role in how much water the body holds on to. This could contribute to changes in fat mass that may affect your day-to-day weight.
Bowel movements can cause fluctuations in body weight, depending on how much waste you excrete daily. About 1.2 bowel movements in a 24-hour period is considered normal.
Constipation, or infrequent bowel movements, could cause temporary weight gain due to stool and fluid retention. Looser, more liquid stools could cause temporary weight loss.
What you eat can play a role in the composition of your stool, which can also lead to weight fluctuations. For example, eating a low-fiber diet can make bowel movements smaller and stool less bulky—this has been linked to small reductions in weight.
Overall, small, daily fluctuations in weight are considered a normal part of life and rarely reflect actual changes in body fat. Fluid and food intake, hormones, and other factors can influence your weight.
That means there’s no need to worry about small rises and dips you might see on the scale. However, if you notice a fast, unexplained change in weight (whether it’s an increase or decrease), it’s important to consult your doctor to rule out an underlying medical issue.
