Most people understand that diet and exercise go hand in hand when it comes to weight loss or maintaining a healthy weight. The number of calories taken in needs to balance with the number of calories being used. In the case of weight loss, more calories need to be used than taken in. So if most people understand this concept why is weight maintenance and loss so difficult? Research shows that most people overestimate the number of calories burned during exercise and underestimate the number of calories they put in their mouths, thus throwing the calorie balance off. In one study, participates were asked to walk on a treadmill. After they were done they were asked to go to a buffet and told to eat what they considered was a caloric equivalent to their workout. Results showed that most participants ate two to three times more calories than they burned during the workout. There is no doubt that exercise is necessary to help maintain a healthy weight and lifestyle just be careful not to overindulge.