STUDY:

JOURNAL: JAMA 2003;289:323-330.

AUTHORS: Dr. Anne McTiernan

ABSTRACT: In a recent study, postmenopausal women who began an exercise program of brisk walking or cycling lowered levels of abdominal fat by about 6% and lost weight, regardless of body weight or age. Not surprisingly, the most active women lost the most body fat and the most weight.

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COMMENTARY: In contrast, women who performed only daily stretching exercises actually experienced a slight increase in intra-abdominal fat and weight after 1 year, researchers report in the January 15th issue of the Journal of the American Medical Association.

The study has implications for the soaring rates of obesity in the US. Nearly two thirds of the adult population are now considered overweight or obese.

In the current study, Dr. Anne McTiernan from the Fred Hutchinson Cancer Research Center in Seattle, and colleagues assessed the outcomes of 168 sedentary women, between 50 and 70 years of age, who were randomized to perform moderate-intensity exercises or stretching. All of the women had a body mass index over 25.

The exercisers walked on a treadmill or cycled on a stationery bicycle for at least 45 minutes, 5 days a week, for 1 year. Weight training was recommended but not required. Women in the control group performed a series of stretching exercises 1 day a week for the year.

The most active women, or those who exercised more than 3 hours and 15 minutes a week, lost about 7% of intra-abdominal fat, compared with a loss of 6% among intermediate exercisers, as measured by CT scan.

Those who exercised less than 2 hours and 15 minutes a week lost 3.4% of their intra-abdominal fat, while women in the control group gained 0.1% intra-abdominal fat, the study found.

Body weight decreased by an average of 1.3 kg in the exercise group, while body weight rose slightly in the control group.