Low-glycemic-index diet can be confusing

Diet researchers reported Thursday that a high-protein, low-glycemic-index diet may work best for maintaining a weight loss. But they concede that many people may not understand just how to achieve such a diet.

While it’s easier to understand which foods are high in protein -- eggs, turkey and dairy products -- knowing the glycemic index (GI) of foods can be trickier. Moreover, just because a food is low on the glycemic index doesn’t mean it’s more healthful, said the authors of the Diogenes study, published Thursday in the New England Journal of Medicine. For example, carrots have a high glycemic-index value (72) while chocolate is low (49).

People should aim to eat healthy foods that are low on the glycemic index, the researchers said. A high-glycemic-index food is above 70, while a medium food is from 55 to 70 and a low-glycemic-index food is below 55. The glycemic index refers to how fast carbohydrates are broken down in the body. Those that are broken down rapidly tend to cause spikes in blood sugar that may alter hormones and increase feelings of hunger. Low-glycemic-index foods, that break down slower, may leave a person feeling more satisfied.

The diet is similar to what nutritionists routinely recommend for good health: Avoid fatty foods and added sugar. Eat lots of fruits and vegetables and fiber. Choose whole grains.

For higher protein content, aim to eat lean meat, poultry, fish, eggs and low-fat dairy products, the researchers said.

For low-glycemic-index, choose fruits carefully. Apples, pears and strawberries are lower GI foods while bananas, pineapple, grapes and melon are higher. Nearly all vegetables are low GI except for corn. Carrots, beets and parsnip should be eaten raw to keep the GI level down. Whole grains are much lower in GI than white bread or white rice. Cook pasta and potatoes al dente and eat them cold to lower GI.

“Glycemic index is a difficult concept to follow,” said the lead author of the study, Thomas Meinert Larsen, of the University of Copenhagen. “If you look at tables listing glycemic index foods, the data are not very reliable. It’s very difficult to know if that cereal you just bought is low GI if the information is not provided on the package.”

Here’s a sample high-protein, low-glycemic-index diet from the authors of the study.

Breakfast: Low-fat yogurt with muesli (no added sugar), whole-grain crispbread with low-fat cheese, an orange.

Morning: Vegetable sticks and low-fat cheese sticks.

Lunch: Whole-grain rye bread with lean meat or cold cuts, mackerel in tomato sauce and miscellaneous vegetables.

Afternoon: Whole-grain rye bread with low-fat liver pate and cucumber.

Dinner: Stir-fried turkey with vegetables and whole-grain pasta, avocado salad with feta cheese and sugar peas.

Drink water or low-fat milk.

For more information on the glycemic index, see this website from Iowa State University.

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