Carbohydrate confusion: shedding some light on carbs, high-protein diets and the glycemic effect

American Fitness, Jan-Feb, 2003 by Nancy Clark

Ever since Dr. Atkins came out with his carbohydrate-bashing high-protein diet, active people (who had been happily enjoying bagels, pasta and pretzels) have suddenly started shunning these excellent sources of muscle fuel. Instead, they eat more egg whites, cottage cheese, soy shakes and protein-based foods. Questions abound about the role of carbohydrates in the sports diet--as well as concerns about insulin and the glycemic effect of foods. This article addresses the current state of carbohydrate confusion and provides some clarity for active people who want to eat wisely for good health, high energy, weight control and top performance.

Q. Are carbs fattening? Should I eat less of them?

A. Carbohydrates are not inherently fattening.

Excess calories are fattening. Yet, excess calories of carbohydrates (e.g., bread, bagels and pasta) are actually less fattening than excess calories of fat (e.g., butter, mayonnaise and frying oils) because the body utilizes calories to convert excess carbohydrates into body fat. In comparison, the body easily converts excess calories of dietary fat into body fat. Thus, if you are gluttonous, but want the least weight gain, you might want to indulge in (high-carb) frozen yogurt instead of (high-fat) ice cream.

Q. Is there a difference between the carbs in starchy foods (e.g., bread) and the carbs in fruits, vegetables or candy?

A. As far as your muscles are concerned, there is no difference.

You can carbo-load on jellybeans, bananas or brown rice--they are biochemically similar. Sugars and starches offer the same amount of energy (1.6 calories per teaspoon) and both get stored as glycogen in muscles or used as fuel by the muscles and brain (via blood sugar).

Essentially, sugars can convert into starches and starches can convert into sugars. For example:

* When bananas are not ripe, they are starchy. As they get older, they become sweeter. In fruits, starch converts into sugar.

* When peas are young, they are sweet. As they get older, they become starchier. In vegetables, sugar converts into starch.

Grain foods (e.g., wheat, rice, corn and oats) store their energy as complex strands of sugar molecules--a starch. The starch breaks down into individual sugar molecules (i.e., glucose) during digestion. Your muscles don't care if you eat sugars or starches for fuel because they both digest into the same simple sugar--glucose.

The difference between sugars and starches is their nutritional value. Some sugars and starches are healthier than others. For example, the sugar in orange juice is accompanied by vitamin C, folate and potassium. The sugar in orange soda is void of vitamins and minerals--that's why it's described as "empty calories." The starch in whole wheat bread is accompanied by fiber and B-vitamins. The starch in white bread loses many health-protective nutrients during the refining process. White bread provides muscle fuel, but fewer vitamins.

Q. If carbs aren't fattening, why do high-protein diets "work"?

A. High-protein diets seemingly "work" because:

1. The dieter loses water weight. Carbs hold water in the muscles. For each ounce of carbohydrate you store as glycogen, your body simultaneously stores three ounces of water. When you deplete carbs during exercise, your body releases the water and you experience a significant weight loss. However, it's mostly water, not fat.

2. People eliminate a lot of calories when they omit carbohydrates from their diets. For example, you not only forgo the baked potato (200 calories), but also the two pats of butter (100 calories)on it--creating a calorie deficit.

3. Protein tends to satiate more than carbohydrates. That is, protein (and fat) lingers longer in the stomach than carbohydrates. Hence, a high-protein (and fat) breakfast of eggs and bacon stays with you longer than a high-carb bagel with jam. By curbing hunger, you have fewer urges to eat and can more easily cut calories--until you start to crave carbs and binge eat.

The overwhelming reason high protein diets do NOT work is dieters fail to stay on them for a long time. They may lose weight, only to regain it. The trick to losing weight is learning to manage what you eat. Remember, you should never start a food program you cannot' maintain for the rest of your life. Do you really not want to eat bread, potatoes or crackers ever again?

Q. I've heard white bread is "poison." Do you agree?

A. White bread offers lackluster nutrition, but it is not "poison" nor a "bad" food.

White bread can be balanced into an overall wholesome diet. For example, if you have bran cereal for breakfast and brown rice for dinner, your diet can healthfully accommodate a sandwich made on white pita for lunch.

White bread's reputation for being "poison" is partially due to its high glycemic effect. That is, 200 calories of white bread are quickly digested and cause blood glucose (i.e., blood sugar) to elevate higher than it would with the same amount of whole grain, fiber-rich bread. High blood glucose triggers insulin secretion to remove the sugar from the blood. Insulin can stimulate the appetite as well as fat deposition. If you are physically fit, however, your muscles readily store sugar as glycogen and, therefore, need much less insulin. Hence, active people can handle high-carb foods and have less need to worry about a food's glycemic effect.