5 Things You Need to Know About Marathon Carb Loading

1. If You're Fit, You'll Burn Fat

When we exercise, our bodies use two main types of fuel--fats and carbohydrates. Most of us have enough fat to get us through a long event like a triathlon, but the problem is that the body won't just use fat--it needs carbohydrates too. In fact, the less fit you are the more resistant your body will be to burning fat as fuel. That's why we need a store of carbohydrates, which are stored in the liver and our muscles as glycogen, to get us through a long event.

2. Avoid the Dreaded Bonking

When you exercise slowly, fat is the primary fuel used by your body. However, as you start exercising harder and faster, your body starts burning carbohydrates. Most people have a store of about 1500 to 2000 calories of carbohydrates in your body. When your body uses them all up, it won't go on. Commonly known as "bonking," it's something you want to avoid during a marathon. Bonking means that your body has no more liver glycogen stores, and it leads to dizziness, lethargy and sometimes staggering.

3. How They Used to Do It

Most athletes do some type of carbohydrate loading before a big event like a marathon. In the past, trainers told athletes to go through a glycogen depletion phase one week out from a big event when they trained a lot and deprived their bodies of carbohydrates. Then, in the week before the event, these athletes loaded up on carbohydrates and did very little exercise. However, this form of carbohydrate loading did not work for everyone, and its use has gone out of favor. New research indicates that an athlete should continuously eat carbohydrates during training to maximize carbohydrate stores in the liver and muscles and to avoid the dreaded bonk.

4. Eat 5 Grams for Every Pound

A recent study conducted by sports scientists in Australia showed that athletes who increased their consumption of carbohydrates 24 hours before a race after following a traditional high-carbohydrate diet during training nearly doubled their stores of carbs and had no side effects. These scientists suggest that athletes eat 5 grams of carbs for every pound of lean body weight in the 24 to 48 hours prior to race day. This means that about 70 percent of calories should be carbohydrates. Each oz. of glycogen that is stored in the body needs 3 oz. of water, so it's important to drink at least half your body weight in water when carbohydrate loading.

5. Stay Away From Junk Carbs

Of course, there are carbohydrates that are healthy and those that are not. Fruits, whole grains, oatmeal and sweet potatoes are good choices. No matter how closely you follow this model, you're not going to feel good and run well if you eat highly processed carbohydrates. It's also important to get enough lean protein and fats during this time.