When we set out to shed a few pounds, we want those pounds to come from fat. Trouble is, it can be tough to know exactly where our weight loss is coming from—especially at first. Here’s how to tell if you’re losing water weight instead of fat.
1. You’re On A Low-Carb Diet
Some research suggests that following a low-carb, high-protein diet can be a safe and effective way to lose weight. (By low-carb, we’re talking like 60 grams of carbs per day.) In fact, one study published in the Journal of Pediatrics found that obese adolescents who limited carbs to just 20 grams a day (and increased protein intake) lost more weight in three months than those who limited fat.
Thing is, some of that initial low-carb diet weight loss comes from water—especially if you ate a higher-carb diet beforehand. When we eat carbs, our bodies break them down into glucose. Then, we combine those glucose molecules with water molecules to form a compound called glycogen, which we store in our muscles and liver to use when we need energy later (like during high-intensity exercise). The more carbs we eat and store as glycogen, the more water we store, too.
Until we stop eating carbs, that is. “When we take in fewer carbohydrates, we use up our glycogen stores and release much of that water,” says Alix Turoff, R.D.N., owner of Alix Turoff Nutrition in New York City.
So if you’ve recently gone low-carb, you can expect a few pounds of your weight loss to be from water.
2. You’ve Lost A Lot Of Weight Quickly
Sorry to burst your bubble, but if you’ve lost five pounds after just a week of an intense new diet and exercise plan, most of that is from water, too. Experts typically recommend cutting about 500 calories per day to lose fat at a sustainable rate, which is just about one or two pounds per week, says Turoff. Unless you have a significant amount of weight to lose—like, 100 pounds or more—you can’t really lose more than that pound or two of pure fat that fast.
Even if you don’t slash carbs, cutting calories overall still forces your body to use stored glycogen for energy—and as you use it, you release water. That’s why many of us see significant changes on the scale those first few weeks of trying to lose weight, according to the Mayo Clinic.
Rest assured, as your body adjusts to your new eating and exercising throughout those first few weeks, the weight you lose shifts over to be more from fat than water. “Our bodies don’t store an endless amount of water, so once we shed the excess, there’s no more to lose,” says Turoff. “I have many clients who might lose seven pounds the first week or so of a new regimen and then lose one pound per week for the duration of their program.”
3. Your Weight Fluctuates Dramatically Day-To-Day
If your daily weigh-ins have been all over the place the last couple of days, don’t freak out. It’s pretty darn hard to lose and gain body fat overnight, so chances are you’re just dealing with fluctuating water weight.
Think of it this way: If it takes cutting 500 calories per day for seven days to lose one pound of fat, it’s going to take more than one day of eating indulgently to gain a whole pound of fat. In fact, to do so, you’d have to eat about 3,500 calories more than your body needs. If you usually eat 2,000 calories per day, that’s a whopping 5,500 calories!
However, when you drastically change your diet from one day to the next—say, by going from eating zero carbs to eating all the carbs, and back again—you quickly retain and lose enough water to throw off that scale reading.
Get back to your usual way of eating and hang tight, and the scale will normalize in your next weigh-in or two, says Noam Tamir, C.S.C.S., owner of TS Fitness in New York City.
4. Your Clothes Don’t Fit Any Better Than Before
Regardless of the story the scale tells you, your clothes will always tell the truth about weight loss. If you’re only losing water, you probably won’t notice much of a difference in how your clothes fit, says Tamir. However, if you’re losing fat—and inches—around your waist, for example, your clothes will feel looser and you’ll know you’re losing body fat.
Another way to test whether you’re losing fat or water: Bust out the body fat calipers. These pincers can roughly estimate your body fat percentage, and are an easy way to track your progress. All you have to do is firmly pinch the chunk of skin about an inch above your right hip bone with your fingers, place the caliper over the skinfold, apply pressure until you feel a click, and check the body fat reading on the tool.
How To Make Sure You’re Losing Fat
Get Enough Sleep
Don’t underestimate the power of sleep on fat loss! After all, research shows that sleep deprivation significantly impacts our hunger and satiety hormones.
Take one small study published in The American Journal of Clinical Nutrition, for example: When people slept for just four hours per night for five nights, they ate 300 calories more per day than they did after sleeping for nine hours per night for five nights. To keep your fat loss efforts humming along, prioritize the recommended seven to nine hours of shut-eye per night.
Eat A Well-Balanced Diet
It’s tempting to slash calories and cut all carbs ever out of your life, but this just sets you up for failure in the long-term, says Tamir. You can only white-knuckle it through an extreme diet for so long before your willpower gives out—and that happens a lot faster if you’ve completely slashed carbs and feel too drained to work out.
Instead, fill your shopping cart with high-quality fruits, veggies, meat, poultry and fiber-rich carbs like whole grains and starchy vegetables. Aim to eat a balance of all the macronutrients (fat, carbs, and protein) your body needs and limit your caloric deficit to 500 calories per day, max.
Lift Weights Regularly
Unlike fat, muscle tissue is metabolically active, meaning it uses energy even at rest, says Tamir. So the more muscle you have, the more calories your body automatically uses per day (a.k.a. the faster your metabolism is).
If strength training isn’t already part of your routine, start by adding two to three full-body sessions per week. To emphasize muscle growth, the American College of Sports Medicine recommends lifting a moderate weight for three to four sets of six to 12 reps, and limiting rest periods to one to two minutes.