Fitness more critical to longevity than weight
Weight may be less important in longevity than fitness, according to research from the Cooper Institute for Aerobics Research in Dallas. The study followed 21,856 men, age 30 to 83 at baseline, for 8.1 years. During that time there were 427 deaths adjusted for age, smoking, and alcohol intake.
The authors found that the health benefits of normal weight (BMI of 19-25) are limited to men who have moderate or high levels of cardio respiratory fitness. Unfit men in the same weight range were not protected. They had 2.3 times the risk of all-cause mortality, compared with fit men in this group. At the next weight level, unfit men with a BMI of 25 to 27.8 also had a greater risk of all-cause mortality than fit men in the same group. Fit but overweight men with a BMI of 27.8 or more had a similar rate of all-cause mortality as physically fit men of normal weight.
Current weight guidelines in the United States, which recommend healthy weight as a body mass index from 19 to 25 may be misleading, unless cardio respiratory fitness also is considered, the researchers conclude. They suggest that working to increase fitness may be more important than maintaining lower weight. (Lee CD, Jackson AS, Blair SN. U.S. weight guidelines: Is it also important to consider cardio respiratory fitness? Int J Obes 1998:22[Suppl2];2-7)
Intermittent physical activity works
Who responds best to moderate, intermittent exercise? Maybe the people who need it most.
The advice to accumulate 30 minutes of moderate exercise 5 days a week was tested for its effect on aerobic capacity, body composition and blood lipids, insulin, and glucose in a University of Nebraska study. Of the 13 sedentary, moderately obese women (mean BMI, 32.7; body fat, 40.6 percent) who exercised at this level for 32 weeks, 7 showed improvement, 6 did not. However, those who succeeded best in losing fat and increasing their aerobic capacity were the ones who probably needed it most; they were significantly older, had greater body fat and lower aerobic capacity at baseline.
The researchers say intermittent exercise can provide flexibility for busy people, citing research that shows compliance increased for women who exercised intermittently through the day compared with those who exercised continuously. However, they caution that their research shows the response varies considerably between individuals, as does other research. (Snyder KA, et al. Effects of long-term, moderate intensity, intermittent exercise on aerobic capacity, body composition, lipids and insulin in overweight females. Int J Obes 1997;21:1180-1189).
Fidgeting: every little bit counts
The "fidget factor" and gender made the difference in who gained more weight for 12 men and 4 women who overfed themselves, 1,000 extra calories a day for 8 weeks. Average weight gain was about 10 pounds for the young adults in the study. Some gained as little as 3 pounds and others up to 16 pounds.
On the average, about 56 percent of the excess calories were "wasted," (i.e., they were not stored either as fat or fat-free mass). The calories were dissipated in three ways: by increases in resting energy expenditure, thermic effect of food, and in nonexercise acitivity thermogenesis. The latter accounted for about two thirds of the calories, in small frequent movements, not big movements such as walking or climbing stairs. Those who "wasted" the most calories and gained the least weight stood up more often, stretched, fidgeted, were more restless, moved more in their daily activities. Exercise levels and the thermic efficiency of exercise were unchanged.
However, there was a great deal of variation between individuals. The four women had the smallest increases in nonexercise activity thermogenesis and tended to gain more weight. The researchers concluded that as people overeat, some can effectively dissipate the excess energy so that it is not stored as fat, while others will have greater fat gain and be predisposed to obesity. ( Levine JA, Eberhardt NL, Jensen MD. Role of nonexercise activity thermogenesis in resistance to fat gain in humans. Science 1999:283;212-214)
Metabolic fitness concept
The concept of "metabolic fitness" as a medically based goal for obesity treatment, replacing weight loss, is being proposed by L. Arthur Campfield, PhD, a veteran obesity researcher with Hoffmann-LaRoche.
The metabolic fitness approach recognizes the good general health of many obese persons. Metabolic fitness, defined as the absence of any metabolic or biochemical risk factor for diseases associated with obesity, returns the focus to health. It views weight loss as a modality which can improve metabolic health, rather than an end in itself. However, goals are reachable independent of weight loss, says Campfield.
Improving metabolic fitness focuses on treatment that will reduce abnormal biochemical and behavioral risk factors, and restore them to normal ranges. Interventions will recognize that family history plays a role. They may range from mild to very aggressive. (Campfield LA, role of pharmacological agents in the treatment of obesity, 1997;471-473. Overweight and weight management, S Dalton, edit. Aspen Publ., Gaithersburg, MD.)
Women lead the way in fitness
Women account for about 56% of all health club members and 53% of frequent exercisers, according to a national survey conducted by American Sports Data.
However, the main reason women exercise is to burn fat, says Gregg Hartley, executive director of the Fitness Products Council, sponsor of the studies. Weight loss was cited as the number one reason they exercise by 87.5% of female fitness center members. Muscle toning came first with men, cited by 84.7%. Men still dominate the weight room: 24.7 million lifted weights at least once in 1995. But the number of women who work with free weights doubled in the last decade to 15 million. (Healthy Weight Journal 1998:12:1;2 / Fitness Products Council, N Palm Beach, Fla. April 1, 1997) |
