It's common to experience a weight-loss plateau after you start a new diet plan. That's because, initially, you may be shedding water weight instead of fat. But how can you tell the difference between losing water weight versus fat?
Aside from regularly getting your body fat measured, there's no foolproof way to tell if you're losing water weight or fat. That said, here are some clues that can help you determine if you're experiencing water weight loss versus fat loss.
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Water Weight vs. Fat
The number you see on your scale when you weigh yourself is a measure of every single thing in your body. So, how do you know if you have water weight? Well, we all do. That's because most of the weight in your body comes from water — it's the heaviest component of your body besides your bones, according to Texas A&M University.
When you first start losing weight, most of those initial pounds lost are in the form of water. That's because when you restrict or burn off extra calories through exercise, your body turns to a substance called glycogen for energy.
Glycogen binds to water — in fact, for each gram of glycogen in your muscles, you hold on to 3 grams of water, per a September 2015 report in the European Journal of Applied Physiology. So when you burn through glycogen, you likewise decrease the amount of water in your body.
But the inverse is also true. When you replenish your glycogen stores (by eating carbohydrates), you can regain that water weight quickly.
It's also possible to carry excess water in your body, per Texas A&M University. Water retention can occur for the following reasons:
- You ate too much salt
- You have a thyroid condition
- You have a heart condition
Fat, on the other hand, doesn't fluctuate quite so readily. In fact, as you lose weight or cut calories, your body will fight to preserve fat to use for energy in the future, according to Northwestern Medicine. As a result, fat loss usually only occurs over longer periods of calorie restriction.
What Does Water Weight Look Like on Your Body?
How to Tell if You're Losing Water Weight
So, how do you know if you're losing water weight or fat? Here's how to know if it's water weight specifically:
Your Weight Changes Frequently or Quickly
The amount of water your body holds onto depends on many different things, like your hormones (such as aldosterone and renin, which help regulate your salt and water levels through your kidneys, per the NIH) and salt intake, per Mayo Clinic. So if your routine stays about the same and you're seeing your weight go up and down a lot, that's how you can tell you're losing water weight.
The best method for how to lose water weight depends on why you're retaining fluid — for instance, some people may have to cut back on sodium, while others may have to address a hormone imbalance.
Your Weight Changes Overnight
Similarly, here's another way to determine if it is water weight or fat that you're losing: You gain or lose pounds overnight.
If you lost several pounds overnight, that's a good indication that you've shed water weight, according to Texas A&M University. On the flip side, if you've gained a few pounds overnight, you're probably holding on to excess water.
This differentiates water weight versus fat loss because it requires burning or eating a significant amount of calories — about 3,500 — to change the fat content of your body, per the Mayo Clinic.
Another clue that you're experiencing water retention versus fat gain is if your extremities — your hands, arms, feet, ankles or legs — swell, per the Mayo Clinic.
This is a sign of a condition called edema, which occurs when your body hangs on to excess fluid. It's usually caused by underlying factors like:
- Heart conditions
- Liver conditions
- Kidney conditions
So if you're wondering whether your weight changes are the result of water retention or belly fat, swollen body parts may help you tell the difference.
How to Lose Fat Instead of Water Weight
The best way to shed fat is to eat a nutritious diet and exercise regularly, per the Mayo Clinic. More specifically, you should cut your daily calorie intake by about 500 calories through a combination of eating less processed foods, lowering your portion sizes and moving more.
How to Tell if You're Losing Fat
On the other hand, here's how to know if you're losing weight from fat loss:
You Slowly Lose Weight Over Time
One key way to determine if you're losing fat or water weight is if your weight loss is gradual, according to the American Council on Exercise (ACE). Generally, losing 1 to 2 pounds per week or shedding 1 percent of your body fat per month indicates that you're losing fat, not just water.
This is why it's important to focus on the overall trend of your weight rather than the number on the scale on any given day, per the American Heart Association. As long as you're gradually shedding pounds over time, it's normal to see some weight fluctuations day to day as you balance losing water weight versus fat.
Check Your Body Fat Percentage
Perhaps the most accurate way to determine if you're losing water weight versus fat is to have your body fat measured by a doctor.
According to Kaiser Permanente, there are a few ways to measure body fat:
- Skinfold thickness: During this test, a doctor will use an instrument called a caliper to measure fat thickness on different parts of your body.
- Bioelectrical impedance: During this test, the doctor will pass a small electrical current through your body to measure your body's electrical resistance. They'll then calculate your body fat based on your resistance, height and weight.
- Underwater weighing: Your doctor will weigh you underwater to more accurately measure the weight of your fat compared to other tissues like muscle and bone.
- Air displacement plethysmography: This measures your body in the air (instead of under water).
- DXA: This is a type of x-ray that can identify how much fat tissue you have.
It's important to note that you don't only have to consider fat loss versus water weight loss — you can also shed muscle, per the ACE. You can prevent muscle loss by eating a nutritious diet and incorporating regular strength training into your exercise routine.
- American Heart Association: "The Pros and Cons of Weighing Yourself Every Day"
- Mayo Clinic: "Metabolism and Weight Loss: How You Burn Calories"
- Texas A&M University: "You Asked: What Is Water Weight?"
- European Journal of Applied Physiology: "Relationship Between Muscle Water and Glycogen Recovery After Prolonged Exercise in the Heat in Humans"
- Mayo Clinic: "Diuretics"
- American Kidney Fund: "High Potassium (Hyperkalemia)"
- Merck Manual: "Hypokalemia (Low Level of Potassium in the Blood)"
- American Council on Exercise: "What Are the Guidelines for Percentage of Body Fat Loss?"
- Northwestern Medicine: "How Your Body Fights Weight Loss"
- Mayo Clinic: "Water retention: Relieve this premenstrual symptom"
- Cleveland Clinic: "Why You Shouldn’t Weigh Yourself Every Single Day"
- Mayo Clinic: "Counting calories: Get back to weight-loss basics"
- Mayo Clinic: "Edema"
- Kaiser Permanente: "Learning About Body Fat Testing"
- NIH: "How the Body Regulates Salt Levels"