Over and over I keep hearing that I have to exercise to lose weight. Blah, blah, blah. Where’s the data?
Here it is and it’s not as conclusive as the exercise pushers would have you think.
“Longer-term weight loss after diet and exercise: A systematic review.” International Journal of Obesity (2005); 29(10):1168-1174.
In this review, the researchers found 33 studies studies of diet/exercise/weight loss, but only 6 had direct comparisons of diet alone vs. diet + exercise. Of course, the caveat is that the studies varied widely in how long participants were on the program (10 to 52 weeks). And what did they find?
Diet associated with exercise produced a 20% greater initial weight loss. (13 kg vs 9.9 kg; z=1.86—p=0.063, 95%CI). The combined intervention also resulted in a 20% greater sustained weight loss after 1 y (6.7 kg vs 4.5 kg; z=1.89—p=0.058, 95%CI) than diet alone. In both groups, almost half of the initial weight loss was regained after 1 y.
CONCLUSION: Diet associated with exercise results in significant and clinically meaningful initial weight loss. This is partially sustained after 1 y.
Well. That sounds great. Just for fun, lets do the math.
Adding exercise to diet results in average weight loss difference of 3.1 kg which is 6.8 pounds.
One year later, the exercise/diet group had maintained an average of 2.2 kg greater weight loss which is 4.8 pounds. (And if you look at the individual results of the six studies, in two of them the diet only group had greater weight loss after one year. Interesting, no?)
So, after all is said and done the diet plus exercise group was an average of 5 pounds smaller after a year.
I’m not running and jumping and sweating for five pounds. It just isn’t going to happnen.
Why are these results so counter-intuitive? We’ve had it drilled into our heads that people are fat because they are lazy and don’t exercise. Studies like this are used by professionals to promote exercise programs. I discovered this study in “Physiotherapy Briefings for Physicians May 2008″ which is from the Canadian Physiotherapy Association. They want doctors to send overweight patients to them for exercise programs. It’s advertising dressed up.
If you like to exercise, good for you. Increasing activity so you can participate more fully in life is a good goal but that can be accomplished by taking a walk to the park with your kids.
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May 9, 2008 at 11:22 am
DR
When it comes to metabolism and bodyfat regulation, there are no simple answers. And that is a big problem with these studies. Scientific studies always look for the ‘magic bullet’ single cause solution.
When some people increase their exercise, their appetite increases; for others it falls. Some people find joy when exercising; others don’t
Not fair, but true
But one fact is true. You may not want to run and jump and sweat to lose 5 pounds, but if you are like most North Americans, not running and jumping and sweating will result in gaining excess fat each and every year.
An extra 1/4 lb each month is 3 lbs a year is 60 lbs in 20 years.
By the time someone gains 60 lbs of fat, there sure as heck don’t want to run and jump
May 9, 2008 at 12:26 pm
crazybengal
The myth of exercise for weight control. How many calories in a piece of toast with jam…150. How much exercise will you need to do in order to burn those calories off…walk about a mile and a half. Hmm – so if you had two slices – about three miles. If you think about calories this way…you will be walking a long way just to keep up. It is best to reduce calories rather than simply eating whatever and then think that you are going to be able to burn it all off with exercise. Exercise for muscle strength and cardiovascular fitness is very important but don’t think it can work to make you lose weight without calorie reduction – I know several very fit people who are overweight – in fact – overexercisers. I also know unfit people who are thin. Add to this the myth that fat will make you fat and fat-free with make you thin…and well…
May 9, 2008 at 1:03 pm
Michele
Sure DR … constant slow weight gain will add up but I don’t think “exercise” is necessary to prevent that. Diet is much more important.
It’s not sitting around watching television that makes a person fat; it’s the potato chips and soda and candy and cookies eaten while watching.
May 9, 2008 at 1:24 pm
DR
I agree that food is more important for fat loss than exercise (it is a lot easier to ingest 1000 calories than to expend 100 calories)
However, I disagree that exercise is not necessary. Our bodies are meant to move. Whether it is the treadmill, weight lifting or just a more ‘old-fashioned’ active lifestyle, exercise is vital for general health & body composition
http://secure.cihi.ca/cihiweb/dispPage.jsp?cw_page=media_05jul2005_e
I also agree that there are lots of ‘fat’ workout fanatics. 3 times at the gym each week won’t make up for a poor diet.
But there are also lots of ’skinny-fat’ people who through reduced calories or just through their natural metabolism have low body-fat, but little muscle mass and as a result appear almost like a skeleton covered with a thin layer of fat.
Like I said, human metabolism is not a simple subject.
May 9, 2008 at 3:43 pm
Lynda Lippin
Our bodies are certainly meant to move, but we do need to get out of the mentality that an hour on the treadmill somehow earns us the candy bar (you know, they should just attach the candy machine to the treadmill
). What, and more importantly how much, we eat is what really matters.
May 9, 2008 at 3:48 pm
crazybengal
Interesting – recent information says that short bursts of running when you are out walking is the best way to step up your metabolism – it tricks your body to think you are more active than you really are.
http://preventdisease.com/home/tips76.shtml
interval training – an old idea that appears to work. And the short bursts of running can be as short as a minute or two combined with regular walking.