Why Your Weight May Be Fluctuating (And Why It’s Not Worth Stressing About)

We’ve all been there. You get on the scale one day, feeling like all your working out and healthy eating has paid off, only to see your weight has gone up. While it can be discouraging to see the scale oscillate, the reality is that weight fluctuations are common and, usually, not worth worrying and stressing out over.

In fact, it’s entirely common for your weight to fluctuate from 1-5 pounds throughout the day. But why is this? Let’s break down some of the common causes.

7 reasons why your weight might be fluctuating

1. Excess sodium

Let’s go back to high school biology for this one. Our bodies prefer a balance of sodium and fluids inside and outside our cells. When you disrupt this ratio with excess salt, the body will retain more water to balance things out again. As a result of this extra water, we may look bloated and see a higher number on the scale. While not adding salt to food can be helpful, the primary culprit of excess sodium in our diets is from pre-packaged foods (especially breads and cold cuts). Eating more whole foods, significantly those high in potassium, can help prevent and reduce bloating.

2. Unbalanced meals

All foods and beverages have a weight, so it makes sense that we gain a few extra ounces when we eat or drink. A balanced diet can help food be digested, absorbed, and expelled efficiently.

In contrast, diets low in fiber and high in refined carbohydrates, fats, and sodium take longer to process, so the excess weight may stick around a little longer. Additionally, refined carbohydrates can lead to spikes in insulin. These high insulin levels can then increase the reabsorption of fluid by the kidney, resulting in fluid retention and an increase in your scale.

3. Exercise

When a workout is hard enough, fluid is lost through sweat. However, if you are hydrating properly, this shouldn’t result in a noticeable weight change. But, if you notice that you consistently weigh less immediately after exercising, it could be a sign that you need to drink more during your workouts.

On the opposite side of the spectrum, some people notice that they gain weight after working out, specifically after weight-lifting or starting a new exercise regimen.

When we lift weights, we’re causing tiny tears in the muscle. For our muscles to repair themselves and become stronger, they temporarily hold onto water in the muscle to help with the recovery process. Recently started working out? Our muscles need energy, which is usually glucose from broken down glycogen stores. When we start using our muscles more, our bodies may respond by storing more glycogen to have adequate fuel. Glycogen is stored with water, resulting in an upswing on the scale. However, after a few weeks of your new routine, the body gets more efficient and needs less glycogen for the same energy output. This, in turn, means less water is being retained, and you’ll likely lose most of that water weight.

4. Bowel Movements

As our weight can go up after eating, it only makes sense that bowel movements can also have minor effects on our weight. The timing between how long it’s been between eating, using the restroom, and weighing yourself can all affect that number on the scale.

5. Menstrual Cycle

For women, our weight can fluctuate during that time of the month as hormonal shifts about a week before our periods can cause water retention. The good news is that your weight should go back down within a couple days into your menstrual cycle.

6. Alcohol Intake

Processing alcohol has two main effects on the body resulting in temporary weight gain. The first is that alcohol is a diuretic. When dehydrated, our kidneys try to reabsorb more water, resulting in fluid retention. Secondly, alcohol also slows down the digestion of other substances, which can also lead to increased water weight as well as just having more bulk in our digestive tract. However, alcohol is also high in calories, and it’s easy for actual weight gain to slowly creep up. If you notice that your weight continues to trend up, it may be actual pounds, not water weight, that you’re gaining.

7. Not weighing yourself consistently

This one is a biggie and the most common cause of weight fluctuation that I come across with clients. As you can see from the other 6 causes of weight fluctuation, there are many moving pieces when it comes to how much we weigh. However, as we tend to be creatures of habit, we can get a more accurate assessment of our daily weight by weighing at the same time and in the same clothes (or no clothes). Another key is comparing weights from the same scale each time. Scales need to be properly calibrated, and since it’s highly unlikely that your home scale and the one at the gym are calibrated equally, it isn’t accurate to compare your weight between the two.

When to worry

While 1-5 pound fluctuations day-to-day is perfectly normal, if your weight remains elevated for a week or more or is consistently trending up, it may be a sign of actual weight gain.

Using an app like LoseIt! is helpful as you can look back and see if you’ve been slightly increasing your caloric intake or working out less. If diet and exercise can’t explain your weight gain, it’s worth speaking with your primary care provider to ensure there isn’t a medical explanation for the extra weight.

Additionally, it’s important to seek medical attention if you notice swelling, particularly in your hands and feet, along with shortness of breath and rapid weight gain.

Finally, certain medications can cause weight gain. If you’re concerned that your prescription is getting in the way of your health efforts, continue taking your medication as directed and schedule an appointment to discuss possible alternatives with your medical provider.

The Bottom Line

While weighing daily can help keep some people on track, it’s more accurate to measure your success by looking at your weight trend over several months rather than day-to-day.

Plus, the scale isn’t everything. If you’ve gained pounds but your clothes fit the same (or possibly even better), you may be gaining muscle. Having your body composition checked throughout the year is another important way to measure change.