Exercise: Do It For Your Health!
By David N. Tornberg
Spring 2007
Weight loss results from a simple equation: More calories must be used or “burned” by the body than are taken in by eating.
This “energy deficit” is the cornerstone of any weight-loss effort. One pound of fat represents approximately 3,500 calories of unburned energy. Therefore, burning 3,500 calories is needed to lose one pound. The larger the daily deficit, the more quickly the weight comes off. Reducing calories or increasing physical activity produces an energy deficit – for most people, a combination of these two strategies is best.
In 1996, the U.S. Surgeon General released a report on physical activity and health, which recommended expending at least 150 calories per day or 1,000 calories per week in moderate and vigorous physical activities. This is the level of energy expenditure necessary to reduce the risk of chronic illness, such as heart disease, and to improve mental and physical health. Adults 18 and older should exercise at a moderate level for at least 30 minutes each day on five or more days of the week. Children should participate in 60 minutes of physical activity each day, while parents limit television and video games to two hours or less.
Even when your body is completely quiet, calories are burned performing functions required to maintain life; this is referred to as resting metabolic rate. Metabolic equivalent (MET) measures an activity's intensity. Resting metabolic rate is approximately one MET and reflects the energy cost of sitting quietly. Additional calories are burned when an individual engages in physical activity.
The more intense the activity, the more calories are burned. Moderate activities of three to six METs are characterized by an increased heart rate. Depth of breathing does not restrict the ability to talk. Vigorous activities of more than six METs increase heart rate and breathing to near maximal levels, and generally make it difficult to carry on a conversation.
Most people lead very busy lives and it can be difficult to find 30-60 minutes for continuous exercise each day. Fortunately, studies show that short, intermittent bursts of physical activity (e.g., three 10-minute blocks) are just as effective. You may find it easier to stick with shorter, more frequent, less formal exercise than with longer, structured blocks. Moderate-intensity programs are just as good as or better than high-intensity programs, because people seem to commit to them.
Choose your exercise based on your current physical condition, lifestyle and activity preferences. Also, remember to consult your doctor prior to beginning a workout regimen – especially if you have a pre-existing health condition such as diabetes, hypertension or respiratory or heart disease.
Begin your exercise program slowly and then gradually increase the intensity and duration. Simply increasing physical activity by 30 minutes per day by walking or taking stairs may be all it takes to achieve some weight loss.
Pedometers are a popular way to keep track of how many steps you take – 2,000 steps is approximately one mile. A sedentary adult walks about 1,000-3,000 steps, or 0.5 to 1.5 miles each day. Walking 2,000 more steps each day takes only 15 minutes and may burn an extra 100 calories. Gradually working toward a goal of 10,000 steps (five miles) per day is one way to meet the U.S. Surgeon General's exercise recommendation.
You may find more information on physical activity at www.fitness.gov. Also, learn how to match your diet to your physical activity level for weight loss or maintenance on the U.S. Department of Agriculture website at www.mypyramid.gov.
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David N. Tornberg, M.D., is Deputy Assistant Secretary of Defense for Clinical and Program Policy and Chief Medical Officer for TRICARE Management Activity. Visit www.tricareonline.com.
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How Much Energy Do You Burn During Physical Activity?
Estimated MET levels for selected physical activities:
|
METs |
Category |
Specific Activities |
|
0.9 |
Inactivity |
Sleeping |
|
1.0 |
Inactivity |
Sitting quietly and watching TV |
|
2.0 |
Transportation |
Driving an automobile or light truck (not a semi) |
|
3.0 |
Walking |
Walking very slowly, strolling, household walking |
|
4.0 |
Lawn and Garden |
Raking the lawn, general gardening |
|
5.0 |
Home Repair |
Cleaning gutters, painting outside of home |
|
6.0 |
Occupation |
Using heavy power tools (jackhammer) |
|
7.0 |
Conditioning |
Stationary bike, ski or rowing machine |
|
8.0 |
Sports |
Competitive basketball game, touch football |
|
9.0 |
Walking |
Climbing hills with a 42 lb. backpack |
|
10.0 |
Water |
Freestyle lap swimming, vigorous effort |
|
11.0 |
Running |
Running at 9 minutes/mile |
|
12.0 |
Bicycling |
Road cycling 14-16 mi/hr, fast or general racing |
|
13.0/14.0 |
Running |
Running at 7-7.5 minutes/mile |
|
15.0 |
Winter |
Competitive speed skating |
Source: Compendium of Physical Activities in the President's Council on Fitness and Sports Research Digests, series 4, no. 2, June 2003 at www.fitness.gov
