CardioSource WorldNews December 2014 - Page 54

Sponsored content CONVERSATIONS with EXPERTS seem mysterious and incomprehensible. But in my judgment, it does not need to be. To me, it may be as simple as this: before meals, many people get hungry; after they eat, people are not so hungry. To its core, that is the neurobiology of caloric balance. The problem is that the neurobiological forces that promote eating during fasting or starvation are far stronger than those that suppress eating when over-eating. Specifically, fat weight loss contributes to neurobiological mechanisms (such as decreased leptin and insulin levels) that promote energy conservation and stimulate starvation eating behaviors—even when the patient is still overweight. What can patients do to combat these neurobiologic forces that promote fat weight regain? One of the best measures to maintain weight loss is to engage in a regular physical exercise program. Regular physical exercise not only burns calories, but it may enhance the effects of leptin and may mitigate counter-regulatory mechanisms that would otherwise promote positive caloric balance. Dr. Cannon: That’s interesting. I’ve heard about the interaction of exercise with metabolic function in the muscles—is that an emerging area as well? Dr. Bays: Yes, it is conceivable that, in addition to the various factors released by adipose tissue and adipocytes, muscles could also produce analogous factors that affect caloric balance. What I find intriguing is all the myths regarding physical activity. One of those is in regard to the optimal type of exercise: either dynamic or resistance. In general, aerobic or dynamic exercises will have the greatest potential for burning calories. However, resistance training may have its own advantages for caloric balance and muscular and bone health. Misconceptions arise when patients are told, “Every pound of muscle gained burns an additional 50 calories per day.” This implies that if 10 pounds of muscle are gained, resting energy expenditure would increase to 500 kcal per day. However, this is misleading. Firstly, for most individuals, gaining 10 pounds of muscle is challenging. Secondly, if muscle weight increases and total body weight decreases, then adipose tissue and the calories required to sustain adipose functionality most likely decrease, as well. Thus, in this situation, the total resting metabolic rate really doesn’t change that much. Because the difference in resting caloric expenditure required to sustain a pound of muscle versus a pound of fat is not as great as people may think. Dr. Cannon: In that vein, there have been some recent studies looking at glycemic control as a surrogate endpoint of metabolic profile in dia- 52 CardioSource WorldNews betic patients. The control group participated in aerobic exercise was compared with patients who performed weight resistance training or both forms of exercise. When each group exercised the same amount, the group who participated in a combination of exercises had better glycemic control. For me, that means aerobic and weight resistance training must each contribute differently to improving the metabolic profile. Is there anything to that notion? that, whichever different validated diet the patient embarks on needs to be individualized based, again, on what works for the individual patient from a neurobiological standpoint, as well as from the standpoint of what the patient is most likely to do. This approach means thinking about the anticipated effect with regard to an individual patient’s glucose levels, lipid levels, and other metabolic parameters. As an endocrinologist who routinely works with F