Carb as Fuel

With the growing popularity of diets like Adkins, Paleo, and the Zone, suspicions about Carbohydrates these days abound. The majority of Americans eat too many carbs per day, however carbs do serve a vital function and can't be cut out completely. Too many carbs can easily be stored away as fat. Not enough carbs and you start to eat into your hard-earned muscle...also not good. Here is how to strike the balance.

Carbohydrates have revolutionized the human condition. They are cheap, easily packaged, and can feed a LOT of people. This was the agricultural revolution that allowed our global population to explode from a small group of rag tag hunters and gatherers to the planet-wide sprawl we see today. The trouble is that we now have the ability to eat these cheap carbs whenever and wherever we choose, and it is very easy to overdo it.

A Bit of Science:

Carbs are made of chains of sugars of various complexity. 'Simple' sugars (like table sugar) digest very rapidly, while 'Complex' sugars (like a sweet potato) take a longer time to get into the bloodstream. The job of carbs is to provide us with energy in the form of Blood Sugar. The blood sugar passes around the circulatory system and drops off energy to the areas that need it. When we eat something with carbs in it, these carbs are broken down and go towards replenishing our blood sugar levels (about 10 grams worth). If the body isn't running low on blood sugar, the carbs get stored away for future use in the liver and the muscles as something called Glycogen (about 300-500 grams worth). If the body is all filled up on glycogen as well, the extra carbs will be stored away as fat. Depending on individual build, this body fat usually shows up first in the chest, belly and face in men, and in the hips, thighs, and triceps of women.

This same system works the other way around when we are burning energy. If I am exercising intensely, my body is using up all the blood sugar as energy. The glycogen in my muscles and liver slowly releases carbs into the bloodstream to keep my levels where they should be. After my workout, the carbs that I eat do not go towards my fat stores, they go towards replenishing my blood sugar and glycogen to get me ready for my next workout. Pretty cool huh?

Some will hear this science and then think, well hey, if I never eat carbs, I'll burn through all my fat stores too! Voila, abs! Unfortunately this is not quite how it works. Say I am exercising, my body is using carbs as fuel and tapping into my glycogen stores. This is all well and good, but let's also say that you haven't eaten a carb in a couple days. The glycogen stores will soon run out. When this happens, the body does NOT start running off of body fat. Body fat takes a long time to burn, and therefore only works as fuel when we aren't moving very fast. Can you guess the time of day we burn the highest percentage of body fat? When we are asleep. It only works when we are not working very hard.

When we ARE working hard, carbs are what fuels the fire. Carbs are the logs in the fire, the coal in the train engine, the gas in the car. When the car runs out of gas, it sputters to a stop. But we don't. If we run out of fuel/carbs, and we still need energy to fuel a workout or to get us to our next meal, we turn to the back-up energy source at high intensities: muscle. Now this is not good. When we chop up our muscle, we lose all the benefits to the speedy metabolism we've developed, not to mention that protein doesn't burn as 'cleanly' as carbs do, and leaves plenty of nasty byproducts like acid and ketones. The example I give to my students is this: You store firewood out in the shed (glycogen), but if you are freezing to death, and you are out of wood, you're going to start burning down the shed for heat (your muscle).

What we try to accomplish on a daily basis is matching carb intake to activity level. If you are running a marathon, eat pasta and drink Gatorades. If you are going to work, and coming home to sit on the couch, you don't need many carbs at all. Imagine trying to run out of gas in your car, just as you pull into your driveway at the end of the day. Finding that carb need balance is what will help you create a lean physique.

Some tips:

Be aware of carb sources in your day. Be thinking about the quantities of bread, pasta, juice, grains, chips, crackers, drinks, and fruit that you take in. The maximum amount of carbs you should be getting in a meal is about a fist's worth. Make a fist, and try to keep your carb serving smaller than that on your plate. Still hungry? Add some more protein! Not a workout day? Maybe think about skipping the carbs for a couple of your meals that day. Often when clients who are seeking to rid some bodyfat decrease their carb intake AND increase their protein, they feel much better within about a week. I hope you do too.