If you’ve purchased pants recently, you may have noticed they have an adjustable or expandable waist. Some men’s pants include up to 2 extra inches to allow you to “flex” or “move more freely.” Women’s pants might have elastic hidden in the waist band for extra “stretch.” While these pants are designed to be comfortable, they could be making you fat!

Most adults gain weight as they age, typically a slow process that may not be noticeable. If you have pants with a 2-inch expandable waist, you could easily gain weight while still wearing the same pants size. In fact, you could gain 2 inches of fat around your waist before you noticed. For many people, tight-fitting pants are a signal that they may have gained weight. By wearing pants with an expandable waist, you are missing that cue, and you could easily gain 5 to 10 pounds or more without noticing it.

This might sound like a minor issue, but these cues are important in helping us recognize weight gain. For example, a man puts on his favorite suit for the first time in over a year to find the pants are too tight. Immediately he realizes he has gained weight since he last wore the suit. Imagine, though, if his suit pants stretched to accommodate his larger waist. He might still think, since the pants fit perfectly, he hasn’t gained weight.

This is important since people typically gain weight little by little over time, which may not be appreciated without these external cues. One way to prevent surprise weight gain is to weigh yourself regularly so you can make adjustments to your diet and activity to prevent further weight gain. In fact, the majority of the “successful losers” in the National Weight Control Registry, a group who has lost an average of more than 66 pounds and kept it off for more than 6 years, weigh themselves at least once a week.

This is also why people who lose weight should get rid of their “fat clothes.” Typically, these clothes get pushed to the back of the closet. But they are still readily available, so when the person regains some of the weight, it is easy to reach further back for a larger size when the smaller clothes in the front no longer fit. If those clothes had been packed away in a box in the attic, retrieving and unpacking them would be a noticeable sign that they had gained weight and may motivate them to get back on their diet.

Even small changes to our diet and activity patterns can lead to weight gain over time. Since this weight gain can often go unnoticed, it is important that we pay attention to external cues. The way our clothes fit is one such reminder, but there are others. Do you notice that you feel more out of breath doing routine activities, like climbing a flight of stairs? This is a sign that your fitness may be declining and that it is time to start exercising. These cues are easy to ignore, but they are important signs that it is time to make changes to our diet and activity. Remember, it is far easier to prevent weight gain or to stay fit than it is to lose weight or get in shape.

Brian Parr, Ph.D., is an associate professor in the Department of Exercise and Sports Science at USC Aiken where he teaches courses in exercise physiology, nutrition and health behavior.