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The Surprising Reason Your Body Actually Needs Exercise

Hint: It has to do with blood sugar, and the way in which your body reacts to it.

… and the drumroll, please: The number one reason your body actually needs exercise is the resulting increased insulin sensitivity.

…the what? Here’s the drill: When you eat food, your blood sugar increases, which, in turn, causes your pancreas to secrete insulin to stimulate your cells in an effort to lower said blood sugar. Insulin sensitivity refers to the amount of insulin required by your body to ultimately lower blood sugar. You are insulin sensitive if your cells easily absorb that circulating insulin (relatively speaking); you are insulin resistant if your cells require more insulin to lower that same blood sugar. (There is a bit more to it than this, of course, but this is the gist.) The ramifications of being insulin resistant include a heightened risk of Type II and Type III diabetes (the latter being closely associated with Alzheimer’s disease). Needless to say, we should all strive for insulin sensitivity.

So back to what being insulin sensitive has to do with exercising: Working out—be it a casual walk or a CrossFit session—improves on this ability for your cells to absorb insulin, increasing insulin sensitivity. And yes, while anaerobic exercise (that exercise that gets you out of breath and working really hard, as well as heavy weight training) increases insulin sensitivity more so than walking, even that casual stroll will help make positive strides (heh) in managing your blood sugar. Indeed, research shows that all causes of mortality decreases in diabetic adults as the amount of walking they do per week increases. The reasons why come from the effect that movement has on your blood sugar, and the associated insulin response.

Now, how much does one have to work out?  In his research, Tim Ferriss (the author behind the best-selling The 4 Hour Body: An Uncommon Guide to Rapid Fat Loss, Incredible Sex and Becoming Superhuman) found that working out at maximal intensity for twenty minutes only three times per week was the minimum effective dose for maximum health benefits. So, if you trained as hard as you possibly could for just twenty minutes on three separate occasions in a calendar week, you could (according to Ferriss) attain all of the health benefits associated with exercise.

And a bonus tip to optimize those workouts? Eat the majority of your carbohydrates in a given day post-workout and in the P.M. This is what I advise all of my clients to do, especially if they are dealing with blood sugar issues. Why? Post-workout, your body is in a state to receive the carbohydrates and shuttle them into the cells of your muscles, rather than storing them as fat. I like to say your cells, after an intense workout session, are like the game Hungry Hungry Hippos. It’s a silly analogy, sure, but remember that game? Pretend those little white balls are the insulin, and, after a workout, those cells inside you are like those hippos just wanting to gobble up that insulin that’s circulating in your blood. Most people have about a 6-8 hour window of heightened insulin sensitivity post-workout.

Resources: Hawley, J.A. and S.J. Lessard. Review: Exercise trainign-induced improvements in insulin action. Acta Physiologica 192:127-135, 2008Dohm, G.L. Exercise effects on muscle insuilin signalling and action: Invited Review: Regulation of skeletal muscle GLUT-4 expression by exercise. Journal of Applied Physiology 93:782-787, 2002Henriksen, E.J. Exercise effects of muscle insulin signaling and action. Invited Review: Effects of acute exercise and exercise training on insulin resistance Journal of Applied Physiology 93:788-796, 2002Gregg, E.W., R.B. Gerzoff, CJ. Caspersen, D.F. Williamson, and KM Narayan. Relationship of walking to mortality among US adults with diabetes. Archives of Internal Medicine 163:1440-1447, 2003


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