In recent articles I have referred to insulin resistance and how it leads to type 2 diabetes about 80 percent of the time. There are two known causes of insulin resistance: being overweight and leading a sedentary lifestyle. There is no clear evidence that one of these conditions is more harmful than the other or is more responsible for insulin resistance.
What is very clear though is that being overweight, even if only 10 pounds or more, and getting little exercise, causes insulin resistance and can ultimately lead to type 2 diabetes.
Now can the insulin-resistant overweight person decrease his or her insulin resistance by losing some weight even if not getting any exercise? Most definitely, no doubt about it.
Generally speaking, in cases where the patient is overweight, weight loss is routinely recommended as a first line treatment for type 2 diabetes. Sometimes simply eating better such as more nutritious foods and less junk food is enough to cause weight loss. When patients can do this it is wonderful, however, research shows that maintaining the weight loss for an extended period of time without simultaneously performing exercise is very, very difficult. As you probably well know the lost weight usually comes back within one to two years after losing it.
What if a person with insulin resistance starts exercising regularly but fails to lose any weight? Is the exercise beneficial? Has it helped? Yes it has, it definitely has, no mistake about it. Exercise will lower insulin resistance even if no weight has been lost. (Are you beginning to see why exercise is such a big deal?) Perhaps the person didn't lose any weight because they made up for the calories burned during exercise by eating more. Maybe the person did lose some fat but gained muscle mass equal in weight to the amount of fat lost. The scale would show no change in weight even though the percentage of body fat had been reduced. Hence, using traditional bathroom scales is a big drawback when measuring exercise/diet success.
Anyway, my point is, that exercise can and does reduce insulin resistance even without weight loss. So when I do encourage exercise it is primarily to reduce insulin resistance and secondarily to promote weight loss.
If weight loss does occur as a result of starting to exercise or exercising more, then you can expect even greater improvements in insulin resistance.
I do want to make it clear that when I recommended exercise to a patient, it is first and foremost to help in reducing insulin resistance, secondarily it is to assist a patient in their weight loss efforts. Research has repeatedly shown that exercise by itself is not likely to result in sustained weight loss. Similarly, research has also shown that diet plans that significantly restrict caloric intake are not successful for long-term weight loss when carried out exclusive of exercise. The best chance for long-term success with weight loss is to gradually work up to exercising a minimum of 250 minutes per week and to reduce caloric intake.