Written by Rebecca M. Speck, M.P.H., and Kathryn H. Schmitz, Ph.D., M.P.H.
More than 500,000 cancer deaths occur in the United States each year. It is estimated that one-third of these deaths can be attributed to diet and physical activity habits, including the roles of overweight and obesity. In the interest of avoiding cancer, behavior choices that focus on achieving and maintaining a healthy weight through physical activity and healthy diet can greatly reduce a person’s lifetime risk of developing cancer.
We know that being overweight or obese is clearly associated with an increased risk of developing certain cancers, including breast (in post-menopausal women), colon, endometrium (uterus), esophagus and kidney. Obesity also likely raises the risk of other cancers, including cervix, gallbladder, Hodgkin’s lymphoma, multiple myeloma, ovary, pancreas, thyroid, and certain types of prostate cancer. There is also ample evidence that regular physical activity is useful for cancer prevention regardless of your body weight.
Achieving and maintaining a healthy weight can be very challenging over a lifetime. We cope with demanding schedules, hectic lifestyles, an abundance of choice, and conflicting information. This is why weight loss or maintenance cannot be based solely on one approach. The best available research indicates that weight loss is most likely to occur by restricting calorie intake and increasing physical activity. Physical activity is essential to weight maintenance and avoiding weight gain (before and after weight loss). The amount of physical activity required for meaningful weight loss is 250 minutes or more per week.
It is understood that weight gain is the result of a combination of eating too much and moving too little. Therefore, weight loss and/or maintenance of a healthy weight should be approached with the goal of reversing both trends, through eating less and moving more.
Eating a healthy diet means making choices that pay attention to what type of calories you are eating and the amount of calories going into your body. A great way to start paying more attention to what you eat is to write down everything you consume for a week and review it. If you notice servings of fried foods, sweets, and soft drinks on a daily basis, note that these have little to no nutritional benefit and are high in calories. Alternative food options might be whole grain pretzels, yogurt, and 100-percent vegetable or fruit juice, which have higher nutritional value. For most adults, a reduction of just 50-100 calories per day may prevent gradual weight gain, making daily food choices very important.
A healthy diet should focus on obtaining a majority of your calories from plant sources. Eat five or more servings of a variety (different colors and textures) of fruits and vegetables each day. Choose breads and cereals that are made with whole grains, as opposed to processed or refined grains. Limit your consumption of processed red meats by choosing poultry, fish or vegetarian options. Finally, if you drink alcohol, limit your consumption to no more than one drink per day for women and two for men.
In regard to physical activity, ACSM recommends adults get 30 minutes of moderate to vigorous aerobic physical activity (brisk walking, cycling, water aerobics, doubles tennis, mowing the lawn) five times a week and muscle strengthening on two or more days a week. If you are trying to lose weight and keep weight off, build to 60 to 90 minutes of moderate to vigorous activity five times per week. Moderate-intensity aerobic activity requires you to work hard enough to raise your heart rate and break a sweat. One good way to judge if you are in this range is if you can talk, but not sing sustained notes. During vigorous-intensity aerobic activity, your heart rate will be very fast and you will not be able to hold a conversation.
When changing your lifestyle to adopt or increase physical activity behaviors, it is important to think about how active you are currently. If you are not physically active, a gradual increase to 30 minutes a day of moderate-intensity aerobic activity will be beneficial and more realistic. A great place to start would be to get a pedometer and write down how many steps you take per day for a week before starting to increase your activity level. Then, increase your daily step count by 10 percent per week until you are doing 30 minutes of some type of aerobic activity on most days of the week. Remember, an initial increase to any amount of physical activity from previously doing none is an improvement! If, on the other hand, you are already achieving 30 minutes on most days, consider elevating your goal to 60 to 90 minutes of moderate or more intense aerobic activity on most days. Just remember – make those increases gradual and realistic for your lifestyle.
Whatever changes you feel ready to make, be assured that even small steps will eventually take you a long way toward preventing cancer!
View the full spring 2009 issue of the ACSM Fit Society® Page online.