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Apart from an iced latte here and a skipped workout there, you’ve been good about sticking to your new health regimen. So it’s frustrating to step on the scale and see your weight has hardly budged. Or worse, you’ve put on a few pounds.

But wait, doesn’t muscle weigh more than fat? You have added pushups to your workouts…

Unfortunately, the odds that you’ve added even a small amount of muscle, let alone a few pounds of the stuff, is highly unlikely, says Dr. Lawrence Cheskin, director of the Johns Hopkins Weight Management Center. “Unless you’re actively body-building”—think hour-long, three-days-a-week weight room workouts—“it’s very hard to gain a pound or more of muscle.”

Even if you are hitting the weights regularly, you’re not going to gain muscle weight rapidly, especially in the beginning. “It’s going to take at least four to six weeks of consistent training to experience significant gains,” says Michele Olson, an adjunct professor of sports science at Huntingdon University. Unless you’re engaged in some Arnold-level lifting, the two or three pounds you’ve added aren’t muscle.

But that doesn’t necessarily mean it’s fat, either. “In the short term, almost any changes in body weight, either up or down, are going to be from fluid shifts,” Cheskin says.

Cut added salt from your diet, and you’ll lose a lot of retained water very quickly. Or, if you weigh yourself after a hard, sweaty workout but before you rehydrate, you’re likely to have dropped a few pounds. “That can be gratifying, but it’s not meaningful,” Cheskin says.

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A new exercise program could also cause you to retain some extra fluid. “When you start working out and you’re sweating, your body is smart, and it understands that its volume of fluid is not at the level it typically would be,” Olson says. In order to prevent dehydration, your body responds by storing extra water, which can cause your weight to increase by a few pounds. The same thing can happen as the summer temperatures tick up and your body adjusts to the added heat and increased rate of sweating. (Combine the onset of summer with a new, intense workout schedule, and you can expect to add at least a few pounds due to water retention.)

On the other hand, you may drop a few pounds when fall temperatures arrive or you quit exercising. “If you’ve been working out a lot and you suddenly stop, I guarantee you will lose some water weight,” Olson says.

MORE: The TIME Guide To Exercise

All of these short-term factors help explain why most exercise physiologists and weight-loss counselors tell people not to get too hung up on the number on the scale. Your body weight is not a static measure or one composed solely of your proportion of fat to muscle. It’s going to slide up and down based on a lot of variables that don’t have much to do with your health.

That doesn’t mean you should trash your bathroom scale; some researchsuggests that overweight adults who weigh themselves regularly are more likely to stick with the diet and exercise routines that help them shed pounds.

But you’re better off weighing yourself just once or twice a week—first thing in the morning, after you pee but before you eat—and keeping track of how your weight shifts over a period of several weeks or months. The long-term pattern of weight gain or loss is a better indicator of how you’re doing. “Especially if you get upset by those day-to-day fluctuations, it’s better not to torture yourself,” Cheskin says.

The best way to keep tabs on your body weight has nothing to do with scales. “Just ask yourself if your clothes are fitting you better or looser, or if you have more energy, or if you feel healthier,” Olson says.

If you answer yes to these questions, whatever you’re doing is working.

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