A Little Carb Cycling Anybody?

If I had no physical performance goals, I think a ketogenic (high fat, low carb, moderate protein) diet would work beautifully to keep energy balanced and blood sugars in a perfect range, 80 – 120 mg/dL. And being fat adapted has other benefits as well. First, appetite is kept under tight control. Second, moderate activities like walking, gardening, playing with the kid, and teaching don’t cause blood sugar to come tumbling down like it would with high levels of insulin circulating in your blood. Finally, mental acuity feels sharp. However, there are some sports where metabolic flexibility is key. My favorite one, competitive swimming, is one of those sports. In a race that lasts less than 60 seconds, sugar is probably the dominant fuel source and it might be beneficial to remind the body how to burn sugar and carbs from time to time. So, I’ve been experimenting with some carb cycling. I’m sure there are 50,000 ways to implement this, but here’s what I’ve been doing:

  1. On days that I swim and lift weights, I’ll eat a sweet potato shortly after workout.
  2. On days I don’t swim or lift weights, I’ll eat a ketogenic diet.

It’s pretty simple and the concept is pretty simple as well. When you intensively work a muscle group, you’ll deplete the glycogen stores in that muscle group thereby priming the cells in that muscle group to accept sugar more readily. Thus, the muscle group is more insulin sensitive following intense exercise like interval training in the pool or lifting heavy weights.

I think this approach has helped me in three ways.

  1. I seem to recover faster after an intense workout.
  2. I seem to have more explosive power and sustained energy during a high intensity workout.
  3. Blood sugars don’t spike as high during intense anaerobic exercise. I think this is because lactic acid build up can be reabsorbed as fuel when the body is better adapted to use sugar for fuel. This third benefit comes in handy during a swim meet when swimming several events in a single afternoon and blood sugar can spike very high following a race. The last thing I want to do is take a large bolus of insulin prior to another race coming up in 30 minutes.

Despite the benefits of carb cycling, eating carbs can be frustrating for a diabetic on insulin. Like Dr. Bernstein reminds us with his “Law of Small Numbers”; eating a large pile of carbs while dosing with a large bolus of fast acting insulin often results in large errors in blood sugar. However, I’m learning that sweet potatoes seem to deliver their insulin demanding starch quickly and up front which makes them more predictable. In contrast to a food like pasta or rice which may deliver their starch in stages over the course of several hours making these foods very unpredictable. None the less, I’m not a fan of having a bunch of insulin coursing through my blood at any time, but I’m going to continue experimenting with carb cycling.

Let me know how you guys are doing out there. Happy holidays.



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