How much exercise is needed to prevent weight gain with age in women? This is a question with conflicting answers, depending on the source. While the 2008 federal guidelines advise at least 150 minutes a week of moderate-intensity aerobic activity for “substantial health benefits,” the Institute of Medicine recommends 420 minutes a week (60 minutes a day) to maintain normal weight. That’s quite a wide range of recommendations!
A recent study reported in the Journal of the American Medical Association (JAMA) examined the effects of different levels of activity on weight in a group of 39, 876 wonen who were part of the Women’s Health Study. Women with an average age of 54 were followed for a period of 13 years, with weights and activity levels assessed at about 3-year intervals. Activity levels fell into three categories: <150 minutes per week, 150 to less than 420 minutes per week, and at least 420 minutes per week.
Results showed an average weight gain over the time period of about 5 pounds. When researchers looked at results based on body mass index, they found that only the women with normal BMIs maintained their weight with 420 minutes or more of activity per week. The women with BMIs of >25 were unable to prevent weight gain, even at the highest activity level. Furthermore, the normal weight women gained weight when they did not maintain a high level of activity.
So, what should we make of this information? I will give you my opinion. First of all, keep in mind that any activity is better than less, particularly for health maintenance purposes. There are many studies that make this point. We also know that active overweight people are generally healthier than sedentary people of normal weight. Secondly, the amount of weight gained was 5 pounds over 13 years, although some gained more and some less. Still, giving up on a healthy lifestyle out of frustration at gaining that amount of weight could result in many more pounds over the 13 year period. Lastly, the study did not look at food intake. It just assumed a normal customary way of eating. That is a big unknown when it comes to weight status!
I found myself wondering if the overweight women in the study may have had more difficulty maintaining weight because of a higher dependence on food as a coping device. For some, this may be just a continuation of a lifelong struggle with weight that has more of its roots in eating than the exercise side of the equation. Without looking at calorie intake, it is difficult to know the details of such a complex factor as eating behavior.
I hope that women do not view this study as just another reason to give up on exercise as a healthy lifestyle component. I still believe that women can make lifestyle changes that can set the stage for a vibrant, active life. Weight loss is possible if real changes can be made that support it. And yes, changing eating habits may have to be a part of maintaining weight with age, but small well-planned changes are quite possible for most of us. I am counting on it!