'Did I really lose weight—or is it just water weight?'

But before you do a little happy dance or treat yo’ self to the chocolate hiding in your freezer behind the broccoli, it’s worth knowing if you legit lost weight or you’re just dehydrated.

So, we asked an R.D. for the questions you can ask yourself to find out if you're dropping fat or just a whole bunch of H2O. Here's your pop quiz.

1. When Was the Last Time You Weighed Yourself?

Weight-loss transformations don’t happen over night, and it’s extremely rare to lose more than one-quarter of a pound of fat in 24 hours. That's especially true if you’re approaching weight-loss in a healthy, no-crash diet way, says Washington, D.C.-based registered dietitian Jessica Swift.

However, over the course of the day or night, it's possible that you could lose up to five pounds of water weight, she says. So if you weighed yourself last night and woke up five pounds lighter, most (if not all) of that was water.

If you weighed yourself last week and lost five pounds, it's more likely to be fat-loss. That's especially true if you lost the same amount of weight this week as you did last week.

2. Is The Weight Loss Steady?

“Real weight loss is consistent, while water weight can greatly fluctuate,” Swift says. After all, if you can lose as much as 10 pounds in water weight in a day, you can gain it back that quickly, too. Each time you step on the scale, consider how your weight has been dropping over time. If you notice a significant loss that seems outside of the norm, it's possible that part of that is due to dehydration.

This is where tracking your weigh-ins comes in handy. To help keep things as consistent as possible, weigh yourself in the morning, ideally after you’ve gone to the bathroom and before you dig into breakfast.

Check out some of the weirdest weight-loss trends through history:

3. What Did You Eat In The Last 24 Hours? Over the long-term (think: weeks and months), the foods you eat make a huge impact in your fat-loss progress. But the foods you’ve eaten in the last 24 hours make the biggest impact on your ever-changing water weight.

While both sodium and carbohydrates are vital nutrients that you need for good health, overdoing them can cause your body to hold onto more water weight than usual, Swift says. On the flip side, cutting sodium or carbs can trigger a quick drop in water weight—which explains why most women lose weight quickly at the beginning of any low-carb diet. So if your last few meals have been significantly less carby and salty, the scale could be detecting a drop in water weight.

4. Where Are You In Your Monthly Cycle? While water retention is a notorious symptom of PMS, that extra poundage tends to let up once your period starts and stays stable until ovulation or later, Swift says. So during and shortly after your period, you might very well be carrying around less water weight than you were before. Call it a consolation prize for all that cramping.