Balancing Food Intake and Physical Activity
SOURCE: DHHS, 2001b.
serious health risks during childhood that can continue throughout adult life.
In the simplest terms, energy balance represents calories consumed versus calories expended, although as noted above, many individual variables can affect that balance. The discretionary variables under an individual’s control on a daily basis are dietary energy intake and the energy expended during physical activity.6 Daily energy intake is determined by the calorie content of the specific food and beverages consumed. Energy expenditure above resting metabolism is largely dependent on the nature and intensity of the activity and is often measured in calories per minute of activity (e.g., walking at a moderate or brisk pace of 3 to 4.5 miles per hour on a level surface expends between 3.5 and 7 calories per minute as measured in adults [CDC, 2004]). Knowing this, it is possible to determine the amount of physical activity that would be required to “burn off” the energy contained in a given food (Box 3-2). The relatively high amount of physical activity required to balance the calories in many preferred foods highlights the challenges of maintaining energy balance under conditions of a sedentary lifestyle and when surrounded by abundant food in large portions at relatively low cost. Much remains to be learned regarding the interactive effects of diet and physical activity—for example, the