Louisville Medicine Volume 63, Issue 2 | Page 13

This concept flies in the face of the laws of thermodynamics, right? As long as I burn more calories than I eat, I will be in a deficit and lose weight. Calories in vs calories out. If you are a cool nutrition blogger, you criticize the “CICO” hypothesis about once a week. It turns out the human body is a little more complicated than simple subtraction. It may be enough to advise people to eat few carbs, thereby releasing little to no insulin, in order to keep adipose tissue in a catabolic state. For patients with carbohydrate intolerance, or insulin resistance, this is likely the best course (though patients taking medications to lower their glucose may have to alter medications). To do this, one can focus on intake of solely fat and protein (which helps with satiety). However, many sources point out certain issues with maintaining a very low carbohydrate diet indefinitely: thyroid dysfunction and overall decrease in metabolic rate, adrenal dysfunction, sadness. So some experts are now recommending one or two days a week of high carb intake in an attempt to “reset” these hormones, and to allow for some pleasure. In addition, this brief and infrequent insulin surge may allow for increased fat oxidation by manipulating the enzymes involved in release of fatty acids from adipocytes. Another concern with low carb dieting and the resultant hormone changes is the wasting of muscle. Insulin has a certain “anti-catabolic” effect on muscle tissue, helping to preserve lean mass. Proponents of the high fat, high protein diet would say that as long as someone is not at a calorie deficit, he or she would not have to be concerned with muscle wasting. But we can cite this potential muscle building effect as further justification for eating moderate carbohydrates weekly. The most proven method to counteract the potential muscle wasting of low carb lifestyles (whether in a calorie deficit or not) is resistance exercise. One or two days of this a week is enough to stress our bodies - making our muscles feel unprepared for life’s challenges. Each day of resistance training should involve bringing muscles to the point of positive failure, known as inroading. This is more safely done with machines, as to “fail” with free weights means getting pinned under a bar; risky even with a spotter. In addition to preventing catabolism of muscle tissue, resistance training unequivocally increases bone density. To use resistance training (or even aerobics) to maximum fat burning potential, do not consume any calories in the several hours prior to a workout. This goes against much of the advice from Gatorade and GNC. If one’s goal is to squat 600 pounds, it can help to eat a Powerbar prior to the workout. But if the goal is fat burning and overall fitness, workouts should be performed while fasting, as tolerated (it takes some adaptation to reach this point). Experts differ on prescriptions for which weight training routines to follow. Some make very good arguments for multi-joint, multi-muscle exercises at heavy weights. Picture Crossfit style, shoulder-dislocating, rectum-prolapsing Olympic lifts. Some encourage weight-lifting three times a week with moderate weights at 4-6 repetitions per set. These regimens can become complicated and veer away from evidence-based guidelines toward anecdotal “bro-science.” Dr. Doug McGuff argues that enough of a stimulus is provided by performing one set of each of five exercises, once a week. The rest of the time, take walks and be as active as possible at work and at home. The five exercises are the chest (bench) press, the overhead (shoulder) press, the row, the pulldown, and the leg press. Each “set” is 10 seconds up, 10 seconds down, using enough weight to reach failure at the 90-120 second mark. His description of the physiology of muscle fiber recruitment is impressive and convincing. We initially use slow twitch fibers in these sets until they fail, at which point the intermediate twitch fibers begin working until they fail. Finally the fast twitch fibers, acting in units with a vast amount of fibers controlled by one nerve, enter into the work of lifting. Before your force is finally overcome by the resistance of the machine, you wil