Exercise Yields Both Visible and 'Invisible' Benefits

Source: Tufts University
February 14, 2003

The ability to wear smaller-sized clothing may be the primary goal of many people attempting to lose weight, but the full benefits of weight loss go much deeper. According to a recent study in the Journal of the American Medical Association, regular exercise not only produces weight loss, but it reduces "intra-abdominal" fat, a type of fat that is close to the heart and may increase the risk for several serious health problems, including diabetes, heart disease, and high blood pressure.

Studying overweight women

Researchers studied 173 postmenopausal women to determine the effects of a prescribed exercise regimen on their amount of intra-abdominal fat (measured by CT scan) and their body weight. The women were between the ages of 50 and 75 (average age 61) and were sedentary and overweight. To be eligible to participate, they had to be nonsmokers, free from diabetes, and not taking hormone replacement therapy.

The women were randomly assigned to participate for one year in one of two groups: an exercise group and a control group. Women in the exercise group performed aerobic exercise, such as treadmill walking or stationery cycling, for at least 45 minutes at moderate intensity, at least 5 days a week. They were encouraged also to do strength-training activities, but this wasn't mandatory. For the first 3 months they performed their exercises in a supervised setting, and then worked on their own for the remaining 9 months. To help measure adherence to the regimen, the researchers required the women to keep daily logs of their exercise activity.

The women in the control group attended weekly 45-minute stretching sessions, and were instructed not to participate in any other form of exercise for the duration of the study.

Exercise yields many benefits

Women in the exercise group exercised at moderate intensity for an average total of 176 minutes per week, or about 3 hours. Walking was the most common activity among the exercisers.

Exercisers lost an average of 3 pounds (1.3 kg) during the study, whereas non-exercisers gained an average of a quarter-pound (0.1 kg). More significantly, the exercisers experienced a much greater reduction in intra-abdominal fat, compared with non-exercisers. This reduction in intra-abdominal fat corresponded to improved cardiorespiratory fitness in the exercisers, as well.

The exercisers who were the most active - exercising for at least 195 minutes per week - experienced the greatest losses in body fat and greatest increases in fitness, compared with the exercisers who were less active, and with non-exercisers.

How does exercise counteract intra-abdominal fat?

The mechanisms by which exercise counteracts the effects of intra-abdominal fat are not fully known. It may be that regular exercise makes the body more efficient at burning fat. Also, the general weight loss that exercise produces may reduce the deleterious effects of intra-abdominal obesity, including increased risk for diabetes, heart disease, and high blood pressure.

Exercising for your own health

These results are encouraging for postmenopausal women, who often battle weight gain during and after menopause and for whom the risk of heart disease often increases dramatically. The results are especially encouraging because even though the overall amount of weight the women in the study lost was low, the benefits to their health by reducing their intra-abdominal fat were potentially significant.

While the results of this study are not necessarily applicable to men or to younger women, they certainly add to an already considerable body of evidence showing that regular exercise is beneficial to health. And because adherence to exercise played a vital role in this study, it's further proof that the best type of exercise for you is the type that you'll enjoy and, therefore, participate in regularly.

Source

• Effect of exercise on total and intra-abdominal body fat in postmenopausal women. ML. Irwin, Y. Yasui, CM. Ulrich,  et al., JAMA, 2003, vol. 289, pp. 323--330

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