Buff: Food as Fuel

Monday, 21 September 2009 19:00

Food’s gotten a bad rap. For most of history, food has been hunted, scavenged, fought over and sought after. Offering the gods a prized lamb signaled the highest devotion. That all changed when industry discovered how to tease more food out of less land. As a 24-hour, all-you-can-eat, fas- food society, we look at food with suspicion: Is that slice of chocolate cake trying to ruin my diet? Is that steak plotting against my heart? Will that soda send me to an early grave? Let’s take a look at food with fresh eyes.

By Tony Federico

On the most basic level, food is fuel—fuel for building bones, muscles, organs, energy for exercise and, when put into storage, fat. So, rather than letting all that fuel get comfortable clinging to your arms, abs, hips, and thighs, put it to use!

Type of activity: Short Duration/Explosive Movements
Fuel: Creatine Phosphate
Where you get it: Meat and dietary supplements

Your body stores a small amount of creatine phosphate in the muscle cells, which can be rapidly broken down for quick bursts of speed (sprinting) or power (Olympic lifting.) The rapid depletion of creatine phosphate means that you cannot sustain a maximum effort for very long without having to slow down so that the body can regenerate its supply. Studies show that supplementation with creatine phosphate increases the amount stored in the body.

Type of activity: Medium Duration/High Intensity Exercise
Fuel: Glycogen
Where you get it: Complex carbohydrates (grains, starchy vegetables, fruits) and simple carbohydrates (fruit, sport drinks, candy)

When carbohydrates are digested, they are ultimately broken down into sugars, which the body converts into glycogen. This process is called glycolysis and is referred to as “anaerobic metabolism” since it does not require oxygen. Most of the bodies’ glycogen is stored in the liver and skeletal muscles. Glycogen is released in order to sustain activity after creatine phosphate has been depleted.

Glycogen can fuel high-intensity activities (medium distance running, rock climbing, martial arts) but will eventually become depleted if additional carbohydrates are not consumed. Endurance athletes will often “carbo-load” to increase their bodies’ stores of glycogen prior to an event.

Type of activity: Long Duration/Low Intensity Exercise
Fuel: Fat
Where you get it: Unsaturated fats (olive and canola oils, fish), saturated fats (butter, lard, tallow)

How it works: A single pound of fat contains 3,500 kilo-calories (what we usually refer to as calories) making it the most efficient way to store energy in the body. Most of our daily activities are fueled by breaking fat down into energy.

Fat oxidation requires the presence of oxygen (thus the term aerobic metabolism) and produces energy more slowly than the breakdown of glycogen or creatine phosphate. During prolonged bouts of activity (distance running, cycling), the body increasingly relies on fats to fuel muscle contractions, but fat’s slow transformation into energy dictates that the activity take place at a lower intensity level. Our bodies carry enough fat to easily fuel several marathons, so fat-loading or fat-supplementation is unnecessary (unless it is fish oils and then as a health consideration).

WHAT ABOUT PROTEIN?

Protein is a complex macronutrient that is made up of many smaller units called amino acids. Many structures in the body, like muscles, skin, and even hair and nails are made from protein. A protein source is considered “complete” if it contains all of the essential amino acids (i.e. those not produced by our bodies). Complete proteins are found in meat products, dairy, eggs and a small number of vegetable sources like soy beans and the grain quinoa. A protein is considered “incomplete” if it is missing any essential amino acids. Most beans, grains, nuts and fruits contain incomplete protein although combining complimentary incomplete proteins like beans and rice or peanut butter and bread is a solution to this problem and an important strategy for vegans and vegetarians.

In addition to aiding in muscle recovery, the body can break down protein from the muscles into amino acids and use them for energy. This happens during extreme bouts of exercise or in cases of crash dieting and starvation. That is why it is important to include protein in your diet and to supplement if you cannot get enough from food alone.

READER QUESTION

What’s the best exercise for burning fat?

Now that you know that fat is the primary fuel source during low-intensity exercise, you may think that low intensity is the best way to target your unwanted fat stores. However, the fact that you are burning primarily fat does not mean that you are maximizing the amount of calories you could be burning. Exercising at high intensities burns more calories overall, and the regeneration of glycogen itself burns fat. So get your heart rate up to get the scale down! Send questions for Tony to This e-mail address is being protected from spambots. You need JavaScript enabled to view it , subject line “Ask Tony.”

Tony is a University of Florida Fitness & Wellness graduate and an ACSM Certified Health & Fitness Specialist working in Orlando. In addition to his contributions to INsite, he also writes for Examiner.com (Orlando Gyms) as well as his own fitness and exercise blog, Orlando Gym Rat.