These days, we don’t have to look very far to see visible signs that our country is facing an epidemic of obesity. With up to 65 percent of the adult population considered overweight in the United States, many of us know family members and friends who fall into this category. If we look in the mirror, we might even include ourselves. Most alarming of all, is the fact that more and more children and teens are overweight—up to 25 percent, depending upon the state. With obesity reaching such high numbers and its connection to many chronic health issues, such as heart disease and type 2 diabetes, it’s a problem that must be addressed now.

However, it’s not always as simple as we think. Most of us are confused about how to go about tackling weight issues successfully. We are often confused about the role of exercise in weight loss—does it really make a difference? Many readers may think that they’re walking or running on the treadmill (literally and figuratively) without seeing a difference in weight. So what’s the deal?

First, it comes down to basic math: Calories in and calories out impact weight. That formula is not going to change. If you consume more calories than you spend in basic needs to keep your body functioning (breathing, circulation) plus what you spend in daily activities, such as walking, gardening, going to the store or even exercising, you will gain weight. If you eat fewer calories than your body burns each day, you lose weight. It’s as simple as that.

However, it’s not so simple to accurately calculate our intake and expenditure based on our perceptions. If we think that spending 30 minutes walking at the end of a day after sitting in front of the computer burns enough calories to make up for an average restaurant dinner, we are mistaken. Most meals consumed when dining out rack up 1,500 to 2,000 calories at one sitting. The average American woman engaged in light activity needs about 1,500 to 1,700 calories per day. (Yes, that includes the half-hour-a-day walkers.) Men with similar lifestyles burn 2,000 to 2,200 per day. Looking at the simple numbers, it’s no surprise that we are struggling to keep our weight in line.

Most of us overestimate the calories expended in our exercise, too. The calories expended during exercise vary depending upon the intensity, duration, and frequency of our fitness activities. For most of us, the average is about 300 to 400 calories per hour. It takes approximately 11 calories per pound to maintain body weight with light activity. In other words, if you weigh 150 pounds, it would only take 1,650 calories per day to maintain that weight. If you spend three hours of time in the gym or exercising that week, you will expend approximately 900 more calories. Your daily maintenance level is now about 1,778. If you ate less than that you would lose weight. If you exercise but consume all 1,778 calories, you will maintain your current weight.

On the other hand, some might try to control their weigh...