In the first part of this series, we investigated impaired glucose tolerance and its effects on weight loss.
As we saw, taking a systematic and comprehensive approach to the assessment of impaired glucose tolerance is the best way to determine if it is present.
In this second part, we will look at how to use exercise as a means to improving glucose tolerance. In the final part, we will review dietary and supplementation as intervention methods.
Exercise is a great way to improve glucose tolerance and, contrary to what you might believe, it is not all about burning calories. While the old-school approach to weight loss says that burning calories is all that matters, newer research into the long-term effects of different types of exercise reveals that a well-rounded activity program is the best bet.
While it may make logical sense to try to burn the most calories in the least amount of time, this approach to weight loss can be very inefficient and can actually make weight loss more difficult.
The confusion stems from the fact the body has two main sources of fuel: sugar and fat. The amount and type of energy being consumed is a function of heart rate.
Naturally, as heart rate increases, the total number of calories being burned increases. However, the percentage of calories from fat actually decreases, until the body reaches anaerobic threshold (AT).
At that point, the cardiovascular system can no longer deliver oxygen fast enough to meet the energetic demands of the muscles. Since oxygen must be present to burn fat, the body's fat burning ability becomes temporarily shut down.
More important, however, are the changes that occur in the body's physiology after exercise.
As high intensity exercise stimulates a release of sugar into the bloodstream, the blood sugar level of a person also spikes after their exercise routine. For the average person, this is not a problem. However, for somebody with impaired glucose tolerance, the sugar spike sets off a cascade of physiological responses that can result in reactive hypoglycemia.
If this occurs, it will trigger powerful signals from a region of the brain called the hypothalamus that will result in exaggerated levels of hunger.
This is why some research has found that people who engage in high-intensity cardio exercise for weight loss often eat more calories after their workout than they burned during the routine.
In 1994, a team of researchers from Laval University compared a traditional aerobic workout program — aimed at burning the most amount of calories during the workout sessions — to an interval training program where short bursts of high intensity are alternated with longer recovery periods. The results were striking.
Even though the traditional group burned twice as many calories during exercise as the interval training group, those who were following the interval training program lost nine times more body fat.
To properly ascertain target heart rates for interval training, it is necessary to perform an O2 stress test. During this test, a gas exchange analyzer is monitoring physiological changes in response to a gradual increase in heart rate. Having an O2 (CardioPoint) test done is essential for anybody who is serious about a weight loss exercise program.
Secondly, it is important not to overlook the value of strength training as a component of a weight loss program, especially if impaired glucose tolerance is present.
Adding some lean muscle mass is one of the best ways to improve glucose tolerance and it also results in a higher resting metabolic rate. Often members are concerned about “bulking up” if they embark on a strength training program. However, it is actually rather difficult to build muscle mass, so these fears are generally unfounded.
Finally, be sure to include some regular activities —such as yoga or stepping in a sauna — that will help reduce stress levels in the body.
While the topic of how stress affects sugar metabolism would warrant an entire article of its own, suffice it to say that high stress levels are another factor that can impair glucose metabolism. There is also a substantive body of research to support the idea that yoga and tai chi have a direct impact on blood sugar control as well.
Prescribed Exercise for Blood Sugar Control
Cardio: 30 to 45 minutes of interval training for two to three times per week
Resistance: 30 to 45 minutes at 65 to 85 percent max for two to three times per week
Yoga or Tai Chi: 60 minutes for one to two times per week
Sauna: 30 minutes for two to three times per week
Following a well-rounded exercise program is not only more effective at blood sugar control, but it can also be more enjoyable. Getting away from the monotony of hitting the treadmill can help keep your weight loss program interesting as well as effective.
In the next article, we will conclude with some tips on diet as well as nutritional strategies for glucose tolerance using herbs and supplements.
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