Wonder why your body weight goes up and down throughout the day? What could be the cause? First of all, chill down! Daily weight fluctuations are perfectly normal. It happens to everyone, regardless of age or fitness level.

Unless you're eating a few thousand calories a day, it's virtually impossible to gain weight from one day to another. The scale might go up because you're holding water, sweating more than usual, or eating a high-carb meal. Not to mention your period, which has a direct impact on body weight.

Weight Fluctuations Explained
Stepping on the scale just to realize that you've gained weight can cause a lot of frustration. After all, you're working out hard and eating clean to stay in shape. This may come up as a surprise, but it's completely normal to fluctuate up to five pounds a day. Most times, a high-sodium intake, constipation, or hormonal changes are the culprit.

Fluid retention, for instance, usually occurs before and during a woman's period, or following a high-sodium meal. Water accounts for about 70 percent of your body's composition. Your blood, muscles, bones, and even fat tissues contain large amounts of water. If you're eating salty foods, your body will hold water.

This problem is more common during pregnancy and menstruation. Lack of exercise may cause fluid retention too. Physical activity stimulates the lymphatic system, which in turn, helps regulate your water levels. A sedentary lifestyle can result in water retention.

Other possible causes include allergic reactions, hormonal disorders, inflammation, kidney dysfunction, thyroid disease, or certain medications.

Common Causes of Weight Fluctuations
If your glycogen stores are full, the scale will go up. After a high-carb meal, your body turns sugar into glucose and uses it to fuel your daily activities. The excess is stored as glycogen in the liver and muscles.
One gram of carbs holds 2.7 to 4 grams of water. Your liver can store 90 to 110 grams of glycogen. The higher your carb intake, the more your weight will fluctuate.

However, those extra pounds are made up of water, not fat. Once you cut back on carbs or break a sweat in the gym, your weight will return to normal.

Let’s say you eat 400 grams of carbs at lunch or dinner. The next day, you'll weigh about 1.6 kilograms more due to fluid retention. Luckily, those extra pounds will melt in the blink of an eye.

Another common cause of weight fluctuations is your menstrual cycle. Women can gain two to 10 pounds during their period. This process usually begins about a week before you start bleeding. You might also experience bloating, digestive distress, swelling, and fatigue. Things are even worse for women with endometriosis.

These changes are due to the increase in estrogen levels and the decline in progesterone levels. Estrogen, the female hormone, causes your body to store water. Progesterone helps reduce fluid retention. During your period, these hormones go and down from one day to the next.
Weight fluctuations can be also due to certain medications. Beta-blockers, non-steroidal anti-inflammatory drugs, and estrogen-containing drugs are notorious for their ability to cause fluid retention. For instance, ibuprofen and aspirin contain substances that fight inflammation. The same substances cause your body to hold water. A high-sodium diet can amplify their side effects.

The good news is that weight fluctuations don’t necessarily mean you’re getting fat. It takes 3,500 extra calories to gain one pound of fat.  Thus, it’s unlikely to gain actual weight within 24 hours or less.

If your weight goes up and down on a daily basis, tweak your diet. Cut back on salt and carbs, hit the gym harder, and get more sleep. Beware that stress may result in fluid retention too. Catching more Zzz’s can help prevent this issue.

Summary

• Daily body weight fluctuations are perfectly normal and happen to everyone. 
• Possible causes include a high-sodium intake, carb-rich meals, hormonal changes, and the use of anti-inflammatory drugs or painkillers. 
• The best way to minimize weight fluctuations is to limit your carb and sodium intake.