Thursday, December 23, 2010

Exercise 6hrs/wk for 20 years. Still gain weight. :(

I guess the good news is that you gained less weight. The bad news is if your motivation for exercising was weight loss, your 20 years of exercise not only didn't help you lose weight but your weight gain was only marginally less than your couch potato friends.

What am I talking about?

A study published last week in the Journal of the American Medical Association which using data from the CARDIA trial, sought to examine the relationship between exercise and weight gain over a 20 year period.

3,554 young adult participants were followed through to middle age. At baseline and years 2, 5, 7, 10, 15 and 20, their physical activity was measured by means of the CARDIA Physical Activity History questionnaire which scored, you guessed it, physical activity. Subjects were also weighed and had their heights and waist circumferences measured at all visits. Dietary intake was examined at baseline and years 7 and 20 by means of a food frequency questionnaire.

The results?

After controlling for age, race, baseline BMI, education, smoking status and alcohol use, habitual high activity was associated with smaller increases in weight and waist circumferences. Men who exercised a minimum of 5 hours a week gained 5.7 fewer pounds, and had 1.22 inches smaller waists than men exercising less than 90 minutes a week. Women who exercised a minimum of 5 hours a week gained 13.42 fewer pounds (though women as a percentile gained more weight than men in total) and had 1.54 inches smaller waists than women exercising less than 90 minutes a week.

Put another way, exercise 1hr/day, 6 days a week and if you're a man you'll gain 4.5 fewer ounces a year than if you exercised less than 15mins/day. If you're a woman you'll gain 11 fewer ounces.

But you'll still gain.

Put another way - it ain't about exercise.

If you want to manage your weight, you've got to manage your intake.

Of course if you want to stay healthy, you've got to exercise. No one said life was fair, so exercise to improve your cardiovascular health, reduce your risk of diabetes, improve glycemic control, increase your mobility, increase your endurance, extend your life and provide you with functional independence.

But please, please don't make the mistake of honouring your New Year's weight loss resolution by exercising like stink and not changing your diet because in a best case scenario it would seem that all you'll end up doing is gaining less in 2011 and likely quitting an incredibly beneficial and healthful behaviour because it didn't lead you to dramatic weight loss results.

Hankinson, A., Daviglus, M., Bouchard, C., Carnethon, M., Lewis, C., Schreiner, P., Liu, K., & Sidney, S. (2010). Maintaining a High Physical Activity Level Over 20 Years and Weight Gain JAMA: The Journal of the American Medical Association, 304 (23), 2603-2610 DOI: 10.1001/jama.2010.1843

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