Not sure how many more posts will have the same title but yet another study has come out that suggests exercise doesn't have a tremendous impact on weight.
This study, out of Harvard, tracked 34,000 women for 13 years and monitored their weight and their exercising.
Only 13% of the women didn't gain weight over the course of those 13 years and those women began the study at a healthy weight and exercised on average an hour a day.
For women who began the study overweight, no amount of exercise was sufficient to prevent weight gain.
The lessons to be learned?
1. Intake, not output, is what has got us into this mess.
2. If you are part of the nearly 2/3rds of the population who's overweight or obese exercise alone is not likely to help you maintain your weight let alone help you to lose it.
3. If you've got a healthy weight and don't want to gain you'll have to do a ridiculous amount of daily exercise.
and most importantly,
4. The more research that gets published failing to show causal benefit to exercise on weight loss the more difficult it'll be to promote exercise.
What I mean by that statement above is that each and every time studies like this are splashed around the newspapers and blogosphere it diminishes the absolute importance of exercise. That's just plain bad because exercise is likely the second most important determinant of health (nutrition being the first).
To me it seems the story on exercise is very clear - it's absolutely crucial for health, in extreme quantities it's helpful for maintaining weight, and it's really, really lousy as an exclusive modality for weight loss.
Bottom line? I would love to see more studies funded to demonstrate the health benefits of exercise and less studies funded that ultimately serve only to dissuade people from bothering to exercise in the first place by having outcomes that are extremely, predictably, disappointing.
I-Min Lee, Luc Djoussé, Howard D. Sesso, Lu Wang, & Julie E. Buring (2010). Physical Activity and Weight Gain Prevention Journal of the American Medical Association, 303 (12), 1173-1179