Diet Fundamentals: Carbohydrates

Carbohydrates are the body's primary and most easily available source of energy. All carbohydrates are sugars, molecules containing carbon, hydrogen and oxygen synthesised by plants through the process of photosynthesis (using the energy of the sun) or by animals through the process of glycogen synthesis. But when I say sugar I don't mean the table sugar that you put in your coffee or on your morning cereal. There are a wide variety of different carbohydrates, and the following are the basic carb categories:

Monosaccharides
Glucose (blood sugar)
Fructose (fruit sugar)
Galactose (a kind of milk sugar)

Oligosaccharides
Sucrose (table sugar)
Lactose (milk sugar)
Maltose (malt sugar)

Polysaccharides
Plant polysaccharides (starch and cellulose)
Animal polysaccharides (glycogen)

How quickly carbs are metabolised by your body (converted into usable substances) is measured by something called a Glycemic Index. A high GI (large increase of serum glucose) means the carbs are metabolised quickly; a low GI (relatively small increase of serum glucose) means they are metabolised more slowly or differently. The Glycemic Index has replaced the former terms of simple and complex carbs. What were once called simple carbs are now categorised as those with a high GI value (fruits, processed sugars), and complex carbs are characterised by a low GI value (starches, cellulose). Carbs with a low GI provide their energy over a period of time, and therefore have a kind of time-release effect. By the way, you often have to look up foods in a guide to be certain of their glycemic index. Ice cream, because of the fat it contains, has a relatively low glycemic index. The kind of rice you get at a Chinese restaurant (the kind that sticks together so well), has a surprisingly high glycemic index, unlike brown rice or wild rice.

As explained, carbs are the easiest form of food for the body to convert into energy. Once ingested, they are turned into glucose, which circulates in the bloodstream and fuels muscular contraction, and glycogen, which is stored in the muscles and the liver for future use. Adequate supplies of carbs are essential for the serious bodybuilder for a number of reasons:

1. Carbohydrates are a primary source of energy. The carbs stored in the muscles as glycogen are what allow you to do heavy, intense weight training.
2. Muscle size is increased when the body stores glycogen and water in the individual muscle cells.
3. Carbs in the body have a "protein-sparing" effect, keeping the body from burning up excessive protein for energy - I'll get back to this point later.
4. The carbohydrate glucose is the main source of energy that fuels the functioning of the brain, and deprivation can have severe effects on mood, personality and mental ability.

The reason that carbohydrates are so important as fuel for intense training is that most exercise like this is anaerobic - that is, it takes place in short bursts, and outruns the ability of the body to supply enough oxygen to sustain the effort, But the structure of carbs is such that they can continue to fuel exercise for short bursts in the absence of oxygen. So when you do a hard set of weight training or run a 100m sprint, the source of your energy for those efforts is primarily carbohydrates.

Carbohydrate Supplements

Intense training creates a demand in the body for glycogen replacement as well as for amino acids. It is important to have enough carbohydrates in your system after training because otherwise the body may start to use amino acids for energy instead. The 'window' for carb replenishment - that is, the period during which the body is in very high demand for this nutrient - is much shorter than it is for protein. In fact, your best results occur when you are able to get the necessary carbs into your body within about 20 minutes of finishing training.

This need for immediate glycogen replacement is why many bodybuilders use a carbohydrate supplement after workouts as well as protein supplements. This is especially important if you follow up weight training with a session of cardiovascular training. If you try to work on a treadmill, stepper or exercise bike too soon after your workout, and your body is carbohydrate-deprived, you will find yourself lacking in energy and you can be sure your body is metabolising more amino acids to supply energy than would be otherwise necessary.

Later in my blogs, I'll go through a set of universal calculations that will provide an estimated value to the number of carbs that you should be looking to take in per day, based on your own specific body and activity requirements. This way, you may then estimate how many carbs you should be looking to take in post-workout. Personally, as I'm currently on a lean training phase, I take in 75g of ground oatmeal with my protein shake. That provides around 48g of fast-absorbing carbs.