Something for the type 2s and pre-diabetic individuals out there: Yet another study released in 2008 showed that older, obese, and sedentary individuals are more likely to develop type 2 diabetes and cardiovascular complications, but that exercise may be the cure-all. The new twist in this study, conducted by researchers at the Cleveland Clinic and published in Journal of Applied Physiology, is that exercise training alone reduces these health risks without significant weight loss. In older, obese men and women, participation in 12 weeks of 60 minutes of moderate aerobic exercise five days per week—with or without a reduced calorie intake—resulted in a greater use of fat by resting muscles and a reversal of insulin resistance.
Prior studies have shown that endurance-trained athletes have higher levels of lipids (fat) stored in their muscles, which in overweight individuals is associated with insulin resistance. Athletes are clearly insulin sensitive, though, which is why this phenomenon has been dubbed the “athlete’s paradox.” Related research conducted at the University of Pittsburgh School of Medicine revisited this paradox by studying older, obese mean and women who undertook a 16-week moderate, but progressive, aerobic exercise training program. The participants’ insulin sensitivity and overall fitness improved due to the training. They also had a 21% increase in the total amount of lipids stored within their muscles, but less fat elsewhere. So, it appears that having excess fat stored in muscles is only bad for insulin action if you’re not physically active. The good news is that aerobic training in particular increases the muscles’ ability to use fat—both at rest and during exercise—even in older, overweight adults who are insulin resistant.