I think most of us would agree that exercise is healthy. It helps the heart to get stronger. It increases our circulation and opens up little microvessels that close down when we lounge around. And it usually makes our blood glucose (BG) levels go down.
But thinking about how healthy exercise is can be easy. It's doing it regularly that is difficult for many of us.
And now comes research showing that 20% of people with type 2 diabetes find that exercise doesn't help them improve insulin sensitivity, improve hemoglobin A1c, reduce body fat, or increase the mitochondria in muscle cells. Mitochondria are the "powerhouses" in cells that burn the food we eat and give us energy.
Their conclusions were based on analysis of previously published studies.
The authors call this effect "exercise resistance", meaning the body is resistant to the benefits of exercise, not that the patients are resistant to the idea of exercise.
Most of this difference in exercise resistance seems to be genetic. Identical twins show the same responses to exercise.
At about the same time this research was published, another study was published that showed that people differed in how exercise affected their fat mass. Of 81 sedentary premenopausal obese women who participated in 12 weeks of a supervised exercise program, some lost weight (a maximum of almost 26 pounds) but 55 (68%) actually gained weight (a maximum of slightly more than 10 pounds, which was fat mass, not muscle) with the aerobic exercise.
The exercise consisted of walking on treadmills three days a week for 30 minutes at a pace that was 80% of their maximum capacity.
Gretchen Reynolds wrote in the New York Times about the weight loss/gain study.
This phenomenon is something I think most of us patients are aware of. One of the first people to point it out, in the 19th century, was William Banting. He was described as "corpulent," and tried to lose weight with a strenuous exercise program. What he found was that the exercise just made him hungrier, and he gained weight. He is credited with one of the first low-carb diets for weight loss, and that diet worked for him. For some time, low-carb dieting was referred to as "banting."
The problem is, if you tell your doctor you've been exercising religiously and you haven't lost any weight, most doctors will think you're not telling the truth.
Do these various studies suggest that you should just forget the exercise and sit back and enjoy your TV? NO Exercise has more benefits than just promoting weight loss and better BG levels. It's good for your heart, for one thing.
If you find that exercise makes you hungrier, try to figure out how to feed that hunger without overeating. Or exercise after you eat.
Note that the first study that showed that 20% of people with diabetes don't see benefits from exercise means that most people (80%) with type 2 diabetes do see benefits in controlling their weight and BG levels with exercise. It's definitely worth trying, because the chances it will help you are greater than the chances it won't.
But if you're very diligent about getting good exercise every day and it doesn't seem to be helping you, don't let your doctor accuse you of claiming to exercise when you didn't. You may be one of the nonresponders.