South Beach dieter cyclist “hits the wall” at mile 50, and asks RD: “How do I build up my glycemic stores so that it remains consistent with my weight program?”

Between your muscles, liver and blood a 150 pound person has about 1800 calories of carbohydrates stored. When your muscle glycogen (stored formed of carbohydrates) get too low, you “hit the wall,” you become fatigued and need to quit.
In comparison to the approximate 1800 calories of stored carbohydrates, the average, lean 150 pound also has about 60-100K calories of stored fat-enough to run hundreds of miles! Unfortunately, for endurance athletes, fat cannot be used exclusively as fuel because the muscles need a certain amount of carbohydrates to function well; carbohydrates are a limiting factor for endurance athletes.
To maintain adequate glycogen stores for long distance rides or runs, 60-70% of diet should be carbohydrates. Your plate should be 2/3 carbohydrate, ½ protein/fat.
Which foods contain carbohydrates? Bread, breakfast cereal, rice, potatoes, oatmeal, fruit, fruit juices, beans, vegetables and milk and dairy.
But not all carbohydrates are created equal. Some researchers have suggested that, depending on how quickly a food is able to raise blood sugar, there may be an effect on performance. This concept is known as glycemic index. This might mean all sources of carbohydrates in food products (including bars, gels, and drinks) are not the same. The higher the glycemic index, the higher the rise in blood sugar.
To help built up your glycogen stores, your snacks and meals should be 2/3 lower glycemic index (GI) carbohydrates. Some examples of these are: pasta, peas, chick peas, lentils, baked beans, peanuts, pears, oranges, sweetened yogurt, apple juice, skim milk.
Conversely, consuming moderate to high GI carbohydrates after exercise help to promote muscle glycogen storage, and to recover between workouts. Some examples of moderate GI foods are: orange juice, Gatorade, rice, oatmeal, whole wheat bread, pineapple, raisins, bananas, and grapes, and some examples of high GI foods are: watermelon, carrots, waffles, bagels, white bread, rice cakes, graham crackers, Cheerios, baked potatoes, mashed potatoes, and honey.
However, as research is controversial and high and low glycemic index foods may not be beneficial for all athletes, I highly recommend to "experiment" with different types of carbohydrates but only to do so during practices not competition.

South Beach dieter cyclist “hits the wall” at mile 50, and asks RD: “How do I build up my glycemic stores so that it remains consistent with my weight program?”

Between your muscles, liver and blood a 150 pound person has about 1800 calories of carbohydrates stored. When your muscle glycogen (stored formed of carbohydrates) get too low, you "hit the wall," you become fatigued and need to quit.

In comparison to the approximate 1800 calories of stored carbohydrates, the average, lean 150 pound also has about 60-100K calories of stored fat-enough to run hundreds of miles! Unfortunately, for endurance athletes, fat cannot be used exclusively as fuel because the muscles need a certain amount of carbohydrates to function well; carbohydrates are a limiting factor for endurance athletes.

To maintain adequate glycogen stores for long distance rides or runs, 60-70% of diet should be carbohydrates. Your plate should be 2/3 carbohydrate, ½ protein/fat.

Which foods contain carbohydrates? Bread, breakfast cereal, rice, potatoes, oatmeal, fruit, fruit juices, beans, vegetables and milk and dairy.

But not all carbohydrates are created equal. Some researchers have suggested that, depending on how quickly a food is able to raise blood sugar, there may be an effect on performance. This concept is known as glycemic index. This might mean all sources of carbohydrates in food products (including bars, gels, and drinks) are not the same. The higher the glycemic index, the higher the rise in blood sugar.

To help built up your glycogen stores, your snacks and meals should be 2/3 lower glycemic index (GI) carbohydrates. Some examples of these are: pasta, peas, chick peas, lentils, baked beans, peanuts, pears, oranges, sweetened yogurt, apple juice, skim milk.

Conversely, consuming moderate to high GI carbohydrates after exercise help to promote muscle glycogen storage, and to recover between workouts. Some examples of moderate GI foods are: orange juice, Gatorade, rice, oatmeal, whole wheat bread, pineapple, raisins, bananas, and grapes, and some examples of high GI foods are: watermelon, carrots, waffles, bagels, white bread, rice cakes, graham crackers, Cheerios, baked potatoes, mashed potatoes, and honey.

However, as research is controversial and high and low glycemic index foods may not be beneficial for all athletes, I highly recommend to "experiment" with different types of carbohydrates but only to do so during practices not competition.