Last updated: 10th May, 2006
KFRU 1400 News-Talk Radio is PedNet's media partner. Thanks very much to KFRU and host David Lile for their support for active living in Columbia.Listen to David's "Daybreak" Show on KFRU on the second Monday of each month between 8:20 and 9:00 a.m. David features registered dietitian Melinda Hemmelgarn, MS, RD and clinical exercise physiologist Tom LaFontaine, PhD, who explain how we can all build active living into our busy lives and make healthier food choices. Join us - David, Tom and Melinda welcome your calls and questions! And check out some of the more frequently-asked questions and the experts' answers below.
For the Active Living Tips Archive (December, 2003 - July, 2005), click here.
INDEX OF QUESTIONS
General Health
How does caloric restriction impact longevity?
Does TV viewing affect children's health?
Physical Fitness
What is the best exercise (quantity and intensity) for fitness improvement?
How long does it take to derive most of the fitness benefits from regular aerobic exercise?
Regarding summer sports, what can you tell me about water and sodium needs?
Nutrition
Is it really possible to eat more and weigh less?
Can you explain the new U.S. Department of Agriculture's Food Guide Pyramid?
What are some health concerns with high salt diets?
Is aspartame a safe artifical sweetener?
Are there recommended limits to fruit juice consumption?
Does soy prevent or promote cancer?
How does diet influence arthritis?"
What exactly is "Slow Food?"
Body Weight Issues
How do I calculate my BMI?
What can be done to reduce childhood obesity?
How does weight influence health?
If I have a larger than desirable waist measurement, can I target weight loss on that one area?
If I'm overweight but active and physically fit, how does my risk for diabetes and heart disease compare with someone of normal weight who is sedentary and unfit?
Is it better to be a little overweight or underweight?
Health Policy
Why should we contact anyone outside our local school board about the kinds of food and drink sold at school lunches and in vending machines?
Does advertising influence children's food preferences?
Information
What web sites do you recommend for health, fitness, and nutrition questions?
EXPERT ANSWERS
How does caloric restriction impact longevity?
It appears that restricting our caloric intake -- by at least 25% -- no easy task -- decreases oxidative damage that we think is largely responsible for aging.
However, when we decrease caloric intake, our metabolic rate slows. This may seem confusing, because for ideal weight loss and fitness, we recommend cutting calories while increasing physical activity to preserve and build muscle mass to keep metabolic rate -- or calories burned at rest -- from slowing down.
Most people in our society would not be very happy on very low calorie diets. Plus, it's difficult to get all the nutrients we need on such low calorie diets. For women, I don't recommend eating less than 1200 calories a day. In addition, with extreme caloric restriction, it's easy to become obsessed and pre-occupied with thoughts about food, which could lead to binging.
Better approach: Make smart food choices and eliminate high calorie, low-nutrient foods for the most part. Keep television viewing to a minimum, avoid fast food and soft drinks, and build activity into your day.
Research over the years in essentially all species studied shows that restricting calories can increase life span. However, the kinds of calories we consume is important - in other words, they must be nutrient dense, quality foods. New research on longevity and caloric restriction was reported in the April 5, 2006 issue of the Journal of the American Medical Association.
Does TV viewing affect children's health?
Recent studies document the effects of TV watching on children's activity levels and academic achievement.
What is the best exercise (quantity and intensity) for fitness improvement?
Essentially, cardiovascular fitness can be improved by exercising aerobically at an intensity above 60% of maximal exercise capacity which is approximately 75% of maximal heart rate. Maximal heart rate can be roughly estimated by taking 220 - age; for example a 50-year old would have a predicted maximal heart rate of 170 beats per min (220-50=170). Going by how you feel is useful when it's not recommended, necessary, or possible to measure maximal heart rate in a laboratory. Exercising at an intensity that causes increased breathing and moderate perspiration is generally adequate. The length of a session should be at least 20-30 mins to improve cardiovascular fitness. Exercising for this duration at above 75% of maximal heart rate, 3-4 days per week can result in significant improvement in cardiovascular fitness (10-30% probably). On the other hand to improve health, one should probably exercise longer (30-60 mins, 4-7 days per week) and at a moderate intensity of 55-75% of maximal heart rate. If one is losing weight or attempting to maintain a lower bodyweight, it may take 60-90 mins of moderate intensity, 4-7 days per week. In addition to aerobic exercise (walking, swimming, biking, jogging, etc.), doing weight training 2-3 days per week and stretching 3-4 days per week is also recommended to improve musculoskeletal fitness.
How long does it take to derive most of the fitness benefits from regular aerobic exercise?
First, it is necessary to differentiate between "health" and "fitness" benefits that accrue from a regular aerobic (walking, biking, wheeling, swimming, jogging, etc.) physical activity program (defined as a minimum of 30 minutes most, preferably all, days of the week). "Health" benefits are often thought of as things like improved cholesterol and blood pressure, increased bone density, etc. "Fitness" benefits are generally defined as an increased capacity to perform physical work or exercise. However, in reality, improved "fitness" is also a "health" benefit since, for example, studies show that persons with higher exercise capacities as measured by the maximal ability to use oxygen (higher fitness levels) suffer from less chronic diseases and live healthier, longer lives.
When referring to the time it takes to reap most of the fitness benefits from a regular aerobic exercise program, it takes longer to increase exercise capacity than it does to improve blood sugar, blood pressure, etc. For example over 12 to 16 weeks, previously sedentary persons can increase their ability to use oxygen by 20% to 30% on average. However, after 6 to 12 months of regular training the increase in maximal exercise capacity will be between 20% and 50% over baseline in most persons. This response is termed a chronic effect of exercise and as long as the exercise program is sustained this benefit will be permanent albeit subject to the inevitable decreases associated with aging!
In contrast, "health" benefits such as lower blood fats, improved blood sugar metabolism, lower blood pressure and enhanced arterial function are apparent immediately after an aerobic exercise session and can last up to 24-48 hrs. This is why exercise bouts should be done on most, preferably all, days of the week.
In conclusion, if you are trying to increase your endurance capacity and performance, it's important to be patient and persevere as it takes 6-12 months to gain most of the benefit from a systematic aerobic physical activity program. However, along the way remember that every exercise bout, even intermittent bouts of 10-20 mins, provide immediate "health" benefits!!
Regarding summer sports, what can you tell me about water and sodium needs?
In prolonged events lasting more than 3-4 hours, 1 in 8 persons may develop a potentially deadly problem called hyponatremia (low blood sodium levels). Persons who are particularly at risk are women, persons who gain weight during a marathon, and persons who are exercising continuously longer than 4 hrs. This does not apply to the common recommendation of 30-60 mins, 4 or more days per week. Drinking 6-8 ounces of water every 15-20 mins is fine during exercise of this duration. For more information on fluid intake during exercise, see the March 17, 2005 New England Journal of Medicine article on low blood sodium in Boston marathon runners.
Is it really possible to eat more and weigh less?
If the foods you select are rich in both fiber and water, such as fruits and vegetables, it is possible to eat more and weigh less. See the excellent book by Barbara Rolls, titled "Volumetrics."
Can you explain the new U.S. Department of Agriculture's Food Guide Pyramid?
Unfortunately, most consumers find the new graphic somewhat confusing because exactly which foods to eat more, and especially less of are not clearly depicted on the new version: www.mypyramid.gov. Tom likes the new version's renewed emphasis on whole grains (fiber) and fruits and vegetables, and the guidelines for physical activity - 30 mins most days of the week for general health benefits, 60 mins most days for children, adolescents, and weight loss, and 60-90 mins for weight loss maintenance. The most important take-home message remains consistent among pyramids new and old: eat more nutrient dense foods - those foods that carry the most nutrients along with their calories, and less foods with added sugar, fat and sodium. Don't be confused by the spoof site: www.mypyramid.org!
What are some health concerns with high salt diets?
Diets that are high in sodium (salt is the combination of sodium and chloride) don't necessarily taste salty. That's why and how sodium can sneak up on us. Processed and fast foods are major contributors of sodium to the diet. Read and compare labels to find the sodium in different foods. Both high sodium and high salt diets are associated with increased risk for high blood pressure in sensitive individuals. High salt/sodium diets may also put youth at greater risk for osteoporosis since they increase calcium loss in the urine.
Strategies for reducing the salt in your diet:
Is aspartame a safe artifical sweetener?
The European Union's food safety regulator says that aspartame is safe for consumption, contradicting a scientific study by the Ramazzini Foundation that claimed the artificial sweetener caused cancer. Here is the full article:
Are there recommended limits to fruit juice consumption?
In their revised policy statement, the American Academy of Pediatrics (AAP) has expanded its list of recommendations for pediatricians and parents who want to regulate fruit juice consumption in children:
Does soy prevent or promote cancer?
It is important to remember that lifetime consumption and exposure to soy differs, and it may be more protective against cancer than eating soy only in middle age. There is lots of research in this area. The bottom line is that soyfoods in moderation are fine, but supplements should be avoided. Check with your physician for further assistance.
How does diet influence arthritis?"
Diet affects each person differently, but as a rule, individuals who eat a more plant based diet, with good source of omega-3 fatty acids, seem to have less inflammation and pain.
The Essential Arthritis Cookbook is a fantastic resource for anyone -- young or old -- coping with a variety of forms of arthritis. The book is authored by staff at the Arthritis Center at the Department of Nutrition Sciences, University of Alabama at Birmingham. It is available through Appletree Press, a wonderful source for credible health publications: Call toll-free: 800.322.5679. The latest soft-cover edition was published in 2003.
The University of Missouri has an excellent team of arthritis researchers as well. Exercise is key to maintaining function and Marian Minor in the Physical Therapy department is an expert in this field. The Health Connection, at the Parkade Plaza, offers beneficial programs.
What exactly is "Slow Food?"
When Carlo Petrini, father of the Slow Food Movement, spoke at the W.K. Kellogg Foundation Food and Society Conference, his advice for healthful, quality eating was to eat food that tastes good, is grown with respect for the environment, and is produced in a socially just fashion.
How do I calculate my BMI?
Body Mass Index (BMI) is calculated from a person's weight and height, and is a reliable indicator of body fatness for most people. A BMI of 30 or more indicates obesity among adults. The following site gives details about calculating BMIs and also provides tips on maintaining a healthy weight.
What can be done to reduce childhood obesity?
Changing the environment to support healthy lifestyles is equally as important as personal choice. We have to make living a healthy lifestyle the easiest of all options. The following web sites include information on policy changes that work in schools and communities.
How does weight influence health?
As weight increases, so does risk for heart disease, cancer and diabetes. However, a large waist circumference - at least 35 inches in women or 40 inches in men - may be a better predictor of disease risk than Body Mass Index (BMI) which combines weight and height measurements. The good news is that even modest weight loss can reduce blood pressure, lower cholesterol and blood sugar levels.
If I have a larger than desirable waist measurement, can I target weight loss on that one area?
Unfortunately, "spot reducing" methods, such as doing excessive sit-ups, don't burn fat in one targeted area. However, regular, enjoyable exercise, such as daily brisk walking, will reduce excess fat stores from all unwanted areas. Of course, exercise is only one part of the weight loss equation. As Tom says, "You can't mop up the floor if the water's still running" - in other words, calories taken in must be reduced. Smaller portion sizes and less high-fat, high-sugar, low-nutrient foods will painlessly trim calories. In the winter, enjoy more broth- or tomato-based soups and stews that are chock full of fiber-rich, vitamin-packed, low-calorie vegetables and beans.
If I'm overweight but active and physically fit, how does my risk for diabetes and heart disease compare with someone of normal weight who is sedentary and unfit?
This is a controversial subject. Data from an ongoing study suggest that overweight but physically fit individuals have a lower long-term risk for death and some chronic diseases than those who are normal weight but unfit. However, most of the subjects are middle to upper class caucasians and so there is some debate about how general this finding is.
Numerous other studies over several decades have shown that increased bodyweight is related to increased risk of chronic disease and mortality. For example, Harvard researchers studying 116,564 women over 24 years showed that although physical activity appears to be beneficial at all levels of overweight, it did not eliminate the higher risk for chronic disease and mortality associated with overweight. Compared with lean and active women, lean and inactive women were 55% more likely to die, whereas overweight and active Women were 91% more likely to die. The authors concluded that "both increased body fat and reduced physical activity were strong and independent predictors of mortality". For best health outcomes achieving a normal bodyweight and maintaining a physically active lifestyle are both important and one does not cancel out the ill effects of the other!
For a related news release:
Is it better to be a little overweight or underweight?
Whether it is better to be lean, slightly overweight, or even downright portly, has sparked debate, thanks to the US Department of Health and Human Services and the Centers for Disease Control and Prevention's recent conflicting number crunching over just how many deaths are attributable to overweight and obesity. However, Tom and Melinda agree that regardless of weight, those who are physically active have a health advantage, and being overweight detracts from quality of life and adds to the risk for an assortment of chronic diseases. The ideal is to be of normal weight and physically active and fit!
Why should we contact anyone outside our local school board about the kinds of food and drink sold at school lunches and in vending machines?
Contacting your local state representatives makes sense because they draft state policy. A state policy may be able to protect all schools within the state against food and beverage companies that offer schools financial incentives for marketing their products at school.
Soft drink contracts, in particular, are very lucrative and hard for under-funded schools to resist. However, "junk" foods and beverages contribute to rising rates of obesity, tooth decay, osteoporosis and type 2 diabetes, and end up costing the state over a billion dollars each year in direct and indirect costs. Offering children and teens a choice of foods and beverages that contribute to their health protects parents'rights, values, and freedom to raise healthy children.
California is the first state to pass legislation restricting the sale of nutritionally-poor beverages, such as soft drinks, to children in grades K-12.
For more information, visit the Center for Science in the Public Interest: www.cspinet.org
Does advertising influence children's food preferences?
Yes, indeed! That is the main finding from the Institute of Medicine's latest report on food marketing and childhood obesity.
The IOM Committee of experts in nutrition, communication, law and health reviewed over 120 studies that examined the connection between television advertising and overweight. They found compelling evidence linking food advertising and the increase in childhood obesity. Television advertising in particular influenced the diets, preferences and requests of children under age 12. However, food marketing has moved beyond TV to include video games that feature food products and food-related school-based marketing. The report also recommends that food sold in school be subject to nutritional standards.
What web sites do you recommend for health, fitness, and nutrition questions?