In March of 2002, the American Cancer Society issued new guidelines recommending that adults get at least 30 minutes of moderate activity on 5 or more days of the week to help avoid chronic diseases such as cancer. The Centers for Disease Control and The American Heart Association also call for 30 minutes per day.

Contents:   Common activities count as exercise   How activity helps prevent cancer   Calorie intake guidelines by activity level   Americans still getting heavier   Fat is a community issue

But in September, a prestigious scientific panel issued a report with a new goal, which came as an unpleasant surprise for many Americans. The Institute of Medicine (IOM) recommended a full hour of moderately intense physical activity every day. So what's best for your health? What's best to help prevent cancer? The answers may be in the details.

Breast and colon cancer, for example, are exceptions to the ACS goal of at least 30 minutes of moderate activity five or more days a week. . ACS suggests 45 minutes or more of moderate to vigorous physical activity to help prevent these cancers.

In general, ACS Director of Nutrition and Physical Activity, Colleen Doyle, MS, RD, has mixed feelings about the proposed hour-a-day guideline, "Sixty minutes is a reasonable goal, but the majority of Americans are not yet meeting the 30 minute per day recommendation."

"Our bottom line message is, 'Do something. Do it for at least 30 minutes and try to do more if you can. Try more intense types of exercise and the benefits to your health will be even better,'" she said.

Will people need to double their morning workouts to reach the 60 minutes goal? Maybe not. First, the key phrase is "physical activity," which can include house cleaning, climbing stairs, brisk walking, playing with children, and many other active tasks of daily living. These count toward the 60-minute-a-day activity goal.

Second, if you ramp up the intensity of your movements you can get the health benefits of a 60-minute moderate activity in a shorter time. A statement on the IOM web site explains how this might work.

"Someone in a largely sedentary (stationary) occupation can achieve the new exercise goal by engaging in a moderate-intensity activity, such as walking at 4 miles per hour, for a total of 60 minutes every day, or engaging in a high-intensity activity, such as jogging for 20 to 30 minutes four to seven days per week."

While it's well accepted that physical activity cuts the risk of developing heart disease, many people don't know it can dramatically reduce the risk of cancer, too. Evidence suggests that one third of the 555,000 cancer deaths expected in 2002 are due to an unhealthy diet and insufficient exercise.

Physical activity works directly and indirectly to impact a person's risk for cancer. Being overweight or obese increases the risk of cancer. Being physically active on a regular basis is critically important for weight control, so activity can indirectly impact cancer risk by helping to maintain a healthy weight.

Exercise and a healthy weight also directly effect cancer risk by changing hormone levels. Excess weight increases circulating levels of estrogen and insulin, which can stimulate cancer cell growth. For breast cancer, vigorous physical activity may decrease the exposure of breast tissue to circulating estrogen.

Physical activity may also affect cancers of the colon, breast, and other sites by reducing circulating concentrations of insulin and related growth factors. For colon cancer, physical activity speeds up the movement of food through the intestine, reducing the length of time that the bowel lining is exposed to potentially cancer-causing compounds.

Cancers linked to overweight or obesity include cancer of the breast (in postmenopausal women), colon, endometrium, esophagus, gallbladder, pancreas, and kidney.

The IOM report includes more detailed advice than ever before on the total calories needed for people of different heights, weights, genders, and by levels of physical activity.

For example, a 30-year-old woman who is 5 feet 5 inches tall and weighs 111 to 150 pounds should consume more calories with a more active lifestyle.

Recommended Calorie Daily Calorie Intake:

• Sedentary (inactive): 1,800-2,200
• Moderately active: 2,200-2,500
• Very active: 2,500-2,800

Calculate your own daily calorie intake now with our calories needed calculator. Learn how your lifestyle measures up to ACS guidelines with the interactive nutrition and physical activity quiz.

The new IOM physical activity guidelines are only a small part of a landmark report that will update food labels and US guidelines for a good diet. The scientific community is still evaluating the 936 page report, but its authors made one point crystal clear right away: Americans must balance their diets with their activity levels.

The 60-minute activity goal is based on how much energy is expended on an average day by people who maintain a healthy weight. Fewer Americans are able to do so every year. The number of overweight and obese people in the US has grown steadily over the last two decades to include 64% of the current adult population.

Secretary of Health and Human Services, Tommy Thompson warned of damaging health effects to come. “We’ve seen virtually a doubling in the number of obese persons over the past two decades and this has profound health implications. Obesity increases a person’s risk for a number of serious conditions, including diabetes, heart disease, stroke, high blood pressure, and some types of cancer." he said.

Many American worksites, schools, and towns make it difficult to be physically active and to eat right during a typical day. "We need to find better ways to motivate people to work to change the environments where they live, work, and play to make it easier to be active on a regular basis," explained Doyle.

She suggests that workers urge their employers to provide access to healthy foods and to establish worksite activity programs, and when possible, even offer subsidies for athletic club memberships. Doyle also recommends talking to the school board if physical education classes and/or recess are being cut, and to influence them to provide healthy meals for kids. Community organizations can press for referendums for transportation and recreational areas in neighborhoods, to help encourage physical activity.

"These changes will require new policies to be developed at the local, state, and national levels," said Doyle. It may seem daunting, she admits, but she noted how drastically health behaviors have changed with regard to cigarette smoking. Community and political factors have helped greatly in reducing smoking, she said, and the same types of policy changes will be needed to create healthier environments supporting good nutrition and adequate physical activity.

On a personal level, Doyle says each individual should find the physical activities they like and do them for at least 30 minutes five or more days each week. On a community level people can work for changes that will make a physically active life easier to accomplish.

For more information about nutrition, physical activity, or ACS programs to improve communities call toll free 1-800-ACS-2345.

Sources:

ACS Nutrition and Physical Activity Guidelines for Cancer Prevention

Dietary Reference Intakes for Energy, Carbohydrate, Fiber, Fat, Fatty Acids, Cholesterol, Protein, and Amino Acids (Macronutrients).
Food and Nutrition Board, Institute of Medicine, Academy of Sciences. 2002

Prevalence of Overweight and Obesity Among Adults: United States, 1999-2000, National Center for Health Statistics, October 2002.