In the previous article we looked at the various constituents of the food we eat, such as proteins from meats, carbohydrates from sugars, fats and nutrients etc. This month we will look further at the functions of these basic food constituents within our bodies, specifically in relation to exercise and your personal training. Body chemistry is a complex subject, but there are some basic principles that you can understand.

Energy Usage: Let’s consider for a moment what is going on with the food energy inside your body. Energy is needed to keep your organs moving. Your heart, for example, needs energy to keep pumping, we need energy for breathing and respiration, and your digestive system constantly needs energy too. In fact, all your bodily functions need energy, almost all the time. When your body is using energy, this is usually the energy obtained from food you have eaten. The body needs lots of energy to move all of its muscles. Energy is also used to keep the body constantly warm, at about 32°.

Food energy (carbohydrates and fats) is burned within the cells for heat, movement and various body functions. This food energy is found in the blood supply, after it has been digested. If there is a lack of food energy in the bloodstream, the energy can be sourced from the body’s fat deposits. But this process is not instantaneous – it takes place over a longer term.

Percentage Body Fat & Muscle Mass: You’ll notice that all the energy usage listed above revolves around muscles. The lungs and heart are muscles, and of course our body has plenty of other, larger muscles that assist us to move around in daily life and exercise. Other parts of our body, like bones and fat deposits require very little energy. Therefore, our energy requirements are proportional to our body’s muscle mass, not total weight. (The more muscle mass, the less percentage body fat.)

Metabolism: The term, metabolism, refers to the body’s converting food into energy. Everyone's metabolism is different, but ideally it’s proportional to the amount of muscle mass our body has. Therefore, the more muscle mass, or less body fat, the more energy our body will convert into energy.

It is important to understand that energy burned is energy that would otherwise have been converted to body fat for storage. The higher your muscle mass, or lower your body fat, the more energy your body will use, and the less fat it will store in fat deposits.

Cardio Exercise: You will all be familiar with the treadmill or the exercise bike. When we are running or doing vigorous exercise, your body is expending energy. Remember, energy not burned is energy that would otherwise be stored as fat. When the exercise is over, the energy burning usually ceases too.

Resistance Training: You will probably have noticed that your trainer focuses heavily on resistance training. Resistance training, or weight training, is designed to increase your muscle mass. While doing weight training you are i) expending energy through exercise and ii) building muscle mass. And, of course, increased muscle mass means less fat deposits as you have a higher metabolic rate. The amount of calories you actually burn at rest actually increases when you have more muscle. That’s why most men have naturally higher metabolisms and lower body fat than women, they have more muscle mass.

Protein: Remember last months article – What are muscles made from? They are mostly made of protein. After you have done a significant resistance training workout, your muscles will be slightly damaged. This damage is a normal reaction, because it can easily be repaired. It is easily repaired with protein from the bloodstream – protein that has recently been eaten by us. This is why protein intake is important – it repairs and adds mass to our muscles, which need repairing after a workout. You can see now how things are so closely inter related. When we do resistance training and eat more protein, our bodies gain muscle mass. When we gain muscle mass, our bodies in-turn expend more energy for muscle maintenance, therefore we store less fat!

Do you know someone who is able to eat whatever they like without putting on weight? Most likely, these people already have low body fat and high muscle mass, so their body’s energy requirements are higher, therefore they are able to eat more calories without putting on weight.

Eating & Exercise: Now that we know a little more about the way our body works, let’s look again at our eating patterns.

An average daily energy requirement is between 8,000 and 12,000 kilojoules, with average female requirement being 8,000 to 10,000 kilojoules. You should consult a diet chart for a rough indication of kilojoule content in foods. Consider two snack foods – a Chiko Roll contains 2800Kj, while a carrot contains about 250Kj. You can see how massively different the energy content of foods are.

Everyone has different energy requirements, but keep in mind that it is proportional to your muscle mass and exercise levels and that excess food (energy) is converted to fat.

When you eat carbohydrates, the food gets converted immediately into energy (then possibly fat stores).

When you eat protein, given that you are physically active and doing resistance training, the food gets converted into muscle mass – NOT fat stores.

What you need to do is match your energy intake to your body’s requirements, making sure you don’t eat too much. Any shortfall will be supplied from fat deposits, therefore losing weight! (Be mindful not to restrict your food too much – this actually serves to slow down metabolism and energy usage.) You need to increase muscle mass in order increase the body’s efficiency at burning energy, and also to decrease body fat levels. Of course, this will also make you appear more toned.

© Paul Blackman 2007

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