According to a U.S. study in this week's issue of the Journal of the American Medical Association, women need to get at least an hour a day of moderate exercise if they hope to ward off the creep of extra pounds that comes with aging.
The weekly total of 420 minutes is nearly triple the 150 minutes of moderate daily exercise currently recommended by U.S. health officials and illustrates the challenge North American women face in maintaining a healthy weight.
Preventing middle aged weight gain will require individuals to make changes in their daily routines - like walking or biking to work - but it may also take a shift in policy to make it easier for people in fit exercise into their lives, researchers said.
Six out of 10 Canadian adults are overweight or obese, increasing the risk of heart disease, diabetes and other chronic illnesses.
"From a public health perspective, it would be better to prevent the weight gain in the first place," said the lead researcher from Brigham and Women's Hospital and Harvard Medical School in Boston. There is plenty of research on people who are already overweight, but little on how to prevent weight gain as people grow older.
Canadian exercise guidelines stipulate how much exercise is necessary to achieve health benefits and to reduce the risk of chronic disease. According to Health Canada we should work up to one hour a day of physical activity. How long you need to spend exercising depends on how hard you work out. For example, 30 minutes of moderate aerobic exercise each day like brisk walking is considered enough to provide health benefits.
What researchers are now starting to look at is how much exercise is necessary to prevent weight gain - and this certainly appears more than what's needed to reap certain health benefits.
In the study, researchers followed more than 34,000 healthy U.S. women with an average age of 54 who ate a typical American diet for 13 years. The women reported their weight and weekly exercise totals in the first year, and then at 3-year intervals from 1992 to 2007.
Over the course of the study, the women gained an average of 5.7 pounds (2.6 kg) overall. Only 13 percent of women maintained a healthy weight throughout the study - and those who got an hour of exercise a day on average or more were by far the most likely to be in that group.
Among overweight women, no amount of exercise helped, they found. In other words, if you are overweight you also need to pay attention to the calories you consume to prevent gaining more weight over time.
The researchers said the results suggest that the current U.S. exercise recommendations of 150 minutes per week are not enough to keep middle-aged women from gaining weight as they age.
There's no question that regular exercise is crucial to help people maintain their weight over time and to prevent regaining weight after a weight loss.
I encourage people to try to accumulate one hour of moderate activity daily. Keep in mind you don't have to do all of this at once. You can break up the hour into three 20 minutes bouts if that's easier to accommodate.
And we're not talking about hitting the gym every day. Brisk walking is considered moderate intensity exercise. It comes down to working daily exercise into your schedule. If you don't have a plan leave it until the end of the day, exercise is unlikely to happen.
That said, we need to remember that less exercise - 30 minutes per day - has important health benefits. And if that's less overwhelming and easier for sedentary Canadians to fit into their life, then that should be the goal.
When it comes to weight control, it's also necessary to consider how many calories you consume each day. Experts estimate that if you drop 100 calories per day - by eating less, exercising more, or a combination of the two - you would prevent weight gain over the years, regardless of what you weigh right now.
100 calories isn't much. Have an orange for breakfast instead of a 12 oz. glass of juice. Or reduce your rice or pasta portion at dinner by one-half cup. Or walk 10,000 steps. The trick is keeping this up day after day.
All research on this web site is the property of Leslie Beck Nutrition Consulting Inc. and is protected by copyright. Keep in mind that research on these matters continues daily and is subject to change. The information presented is not intended as a substitute for medical treatment. It is intended to provide ongoing support of your healthy lifestyle practices.