Tuesday, July 03, 2012

That Cheating Heart

When it comes to diets--specifically contest prep, but the theme applies generally--there are two basic techniques that are used.  Most diets fall somewhere along this spectrum.  One on hand, you have the "cycling" technique, where two to three moderately low carbohydrate days are cycled with moderately higher carbohydrate days, maintaining a deficit on all days.  This means that even on "high" carb days, the dieter will still be consuming less than what would be required for maintenance.  On the other end of the spectrum, we have the "cheater" style of dieting.  This is a depletion, or "keto," diet.  Ketosis is the term for the physical state in which an individual has high concentrations of ketones in the blood, caused by the body's inability to provide further energy from stored glycogen.  Ketones are produced in the liver during prolonged fasting or starvation.  Ketones combine with the byproducts of beta-oxidation and can then be incorporated into the Krebs cycle, which I discussed briefly here.  Ketones are not restricted by the blood-brain barrier in the same way albumin-bound fatty acids are and so can bring energy to the brain when sugar is not available.  "Ketosis" is used colloquially to describe a "depleted fat-burning" state.  A diet focusing on sustaining a depleted state in order to burn fat would generally also focus on lowering the intake of carbohydrates and maintaining a high calorie deficit for prolonged periods, usually one week.

While both basic styles have their pros and cons, you will find that most bodybuilders preparing for shows, that is, people on a serious diet, are using the depletion method.  With this method, it's very important to keep in mind that your metabolism is readily adaptable, just like the rest of your body.  Your metabolism will slow to preserve energy as your caloric intake drops--a pretty effective survival mechanism, no?  For this reason, most depletion diets also include "re-feeds" or "cheat" meals or days.  These are not the same thing!  Re-feeds are traditionally the addition of a few hundred grams of "diet" carbs, spread over a few meals on one day--minimal deviation from the originally prescribed food.  Cheat meals and cheat days, on the other hand, are exactly what they sound like: complete deviation from your diet for one day or, depending on your size and sensitivity to diet, one meal.  Either way, both these methods--and the cycling method, for that matter--have the intended effect of preventing complete adaptation of the metabolism.  By giving your body a variable dose of calories on a regular basis, you are telling your body not to panic just yet.

But if you're trying to get leaner, doesn't the cheat day set you back?  No, and here's why:  In trained individuals, the impulses from dieting and training combine to change the body's reaction to excess calories.  When large caloric excesses are consumed for extended periods, the normal reaction of storing the extra energy as fat will invariably resume.  However, when large caloric excesses are consumed infrequently, the body will instead seek to maximize the benefit of the extra calories by using nearly all of them to replenish muscle glycogen, using the rest for tissue repair and maintenance.  Concurrently, muscle mass is nearly 30% stored glycogen.  This means that for a muscular, depleted individual, the amount required to fully replenish glycogen stores is quite large.  Thus the risk of fat gain from weekly cheat meals is nearly zero.  Overdo it and go for three days and I can't promise anything though... #beentheredonethat

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