Registered dietician Karen Collins of the American Institute for Cancer Research responds to health-related questions.
Q: Does waist size matter as long as your weight is OK?
A: Traditionally, greater waist size was considered a marker of especially increased risk among those already at health risk because of being overweight. However, research now shows that even if your overall weight is within the recommended range, large waist size increases your risk of chronic disease and raises mortality rates among middle-aged and older adults. Waist size can reflect excess fat deep around organs in the belly. That belly-fat tissue is especially likely to produce proteins that circulate through the body promoting inflammation, and it’s especially linked to the problem of high levels of insulin that do not function normally.
A recent population study in Germany involving more than 25,000 participants showed that among people of low or normal weight with a body mass index less than 25, women with waist sizes larger than 31.5 inches and men with waste sizes larger than 37 inches were 2 1/2 to 3 1/2 times as likely to develop diabetes as those with smaller waists. The study involved an eight-year follow up.
They were also at least as likely to develop the disease as those who were overweight but had a smaller waist. Another study in the Journal of the American Medical Association reports that even increases in waist that occur when participants are in their 50s and 60s increase risk of diabetes. Analysis in a major report from the American Institute for Cancer Research shows that risk of colon cancer increases 5 percent for each one-inch increase in waist size. The report recommends aiming to keep waist size no more than 31.5 inches in women and 37 inches in men.
Q: What is interval training? Is this really something for athletes or is it good for everyone?
A: Interval training refers to short bursts (intervals) of more intense activity mixed into more moderate activity. The American College of Sports Medicine and American Council on Exercise says it allows you to increase fitness without long periods of running, and you can more rapidly and comfortably achieve higher levels of physical activity. You can include this principle of injecting one or two minutes of faster or more challenging activity into walking, bicycling or almost any type of activity. Start with just a few of these intervals in your activity, but you might work up to 10 or 12 intense intervals per session. Follow each high-intensity period by twice as long a block of lower-intensity activity. This technique of improving fitness can work for people of wide-ranging age and fitness levels, but those at any increased heart-related risk should be sure to discuss this with their doctor in advance. That includes people with known heart disease, as well as people who have ever been given chemotherapy that might have had heart-damaging side effects and people taking medication for high blood pressure.
Karen Collins is a registered dietician with the American Institute for Cancer Research, a cancer charity that fosters research on the relationship of nutrition, physical activity and weight management to cancer risk.