Thursday, July 13, 2006

Does Exercise Boost Metabolism?

If you read Health and Sports magazines you would think so. The hypothesis is that exercise benefits you while you are doing it and hours later. But is there evidence to support the theory? Based on my past exercise history I'd have to say no.
I don't think I've ever not taken some form of daily physical activity although it's varied greatly in its intensity. I've always walked, at least two thirty minute walks a day with the dogs, swum and stretched. I don't think of this as "exercise" more part of my routine.
Then there is the part I consider real exercise. The stuff that raises the heart rate and makes the muscles ache. That's the kind of exercise that's supposed to raise my Resting Metabolic Rate (RMR) so I'll continue to expend energy even after I've stopped the activity. I wish exercise would increase my RMR and help me lose weight. It didn't do it when I was on the school swim team. It didn't do it when I took aerobics classes, step classes or yoga. At my last gym you got weighed when you joined and monthly after that. I was the only person who managed to lose not one pound for the entire time I was there. They didn't believe it. Sadly I did. Been there, done that.
I did a little research because I am convinced I'm not the only person who doesn't lose weight on an exercise regime. Chris Melby, Dr.P.H. writing for the American College of Sports Medicine, ACSM Fit Society® reproduced in Sports Medicine suggests that I'm right. Most of the benefit comes while exercising and the effort put in by the typical gym-goer will not result in substantial changes in RMR. Another article in Peak Performance has even more bad news. Studies report that for some people, exercise may actually lower metabolic rate and it's gender specific too. Women experience less benefit than men because we are more effecient at conserving energy. And for me, as a person with diabetes, when I do get some delayed energy expenditure it sends me hypo so I have to eat to survive. Calories out balanced by calories in = negative weight loss.
That's why I want to work with a personal trainer this time. Maybe I've been doing it wrong all these years, or maybe I just need to do more. I want to increase the intensity of the weight training while controlling extra calorie intake and avoiding hypos. I hope I can also lose some weight but I'll be pleased if I just increase my strength, flexibility and sense of well-being.

1 comment:

Kevin said...

I haven't read the articles you link to, but my understanding is this: weight loss/gain is based on the very simple formula you referenced:

Calories in > Calories out = weight gain.

Calories in < Calories out = weight loss.

Unfortunately, you cannot lose weight by simply being on an exercise regime. If you're more than compensating the engergy expenditure during exercise with increased caloric intake (if the exercise is causing low blood sugars, for example) then you can very easily gain weight while exercising rigourously.

As far as the RMR goes, my understanding was that above and beyond your baseline, routine activity level it was body fat/muscle composition that could potentially affect your metabolic efficiency. And that only significant decreases in body fat or increases in muscle mass would produce noticable affects on one's RMR.

Sounds like you've got the right attitude, though. Increasing strength, flexibility and well-being should be your primary goal. Although avoiding exercise-induced hypoglycemia is a *very* close second.

Best of luck with the new trainer!