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The Promise

Diets based on the glycemic index -- Sugar Busters, the Zone Diet, and Nutrisystem - are more famous than the original “G.I. Diet.”

The glycemic index was designed to help people with diabetes control their blood sugar levels. And what works to control blood sugar, the theory goes, should help you drop extra weight.

Like its better-known children, the glycemic index diet focuses on carbs. It gets a little complicated, but here's the basic idea: Some foods -- like white bread, cookies, and white potatoes -- make your blood sugar rise quickly. On the glycemic index diet, you eat carbs that produce a steadier rise in blood sugar; and the fiber in those foods helps you feel full longer. You're not as hungry, and you feel more satisfied.

Does It Work?

Sticking to a low glycemic index diet may help prevent conditions like diabetes and heart disease.

But it's not certain that this diet can help you lose weight any better or faster than a low-fat, generally healthy diet.

One study showed that people on a low-glycemic diet lost more fat than those on a high-glycemic diet with the same calories. More studies are needed to confirm that.

What You Can Eat

Foods on the glycemic index diet are scored on a scale of 0 to 100 based on how much they raise your blood sugar level.

  • High-GI foods (70 or higher): white rice, white bread, pretzels, white bagels, white baked potatoes, crackers, sugar-sweetened beverages
  • Medium-GI foods (56-69): bananas, grapes, spaghetti, ice cream, raisins, corn on the cob
  • Low-GI foods (55 and under): oatmeal, peanuts, peas, carrots, kidney beans, hummus, skim milk, most fruits (except those listed above and watermelon)

On the diet, you try to eat more foods in the low-GI category, and fewer in the high-GI group.

Level of Effort: Medium

You don't have to do any calorie counting or portion control, and you can eat a pretty varied diet. You also don't need to cut out almost all carbs. You do need to be selective about your carbs, checking the glycemic index value of the foods you eat.

Limitations: The glycemic index diet can be confusing. Just because a food is low on the index doesn't mean it's healthy. And some high glycemic index foods offer a lot of nutrition.

For example, parsnips have a higher glycemic index value (52) than vanilla cake (42).

Also, the diet doesn't offer advice on non-carb foods. It's up to you to figure out how many calories and how much fat you're getting each day. And eating some foods in combination -- like a high glycemic index carb with protein and fat, for example -- can affect how much your blood sugar rises.

Cooking and shopping: You can shop and cook like you normally would, but you need to use ingredients that are low on the glycemic index.

Packaged foods or meals: None are required, but certain programs -- like Nutrisystem -- that follow the glycemic index diet do include packaged meals.

In-person meetings: No.

Exercise: Exercise is not part of this diet.

Does It Allow for Dietary Restrictions or Preferences?

Yes. People who are on vegetarian, gluten-free, and other dietary restrictions can follow this plan. You can choose foods you like, but you may need to make substitutions, such as using whole wheat pasta instead of white.

What Else You Should Know

Your diet needs to be healthy, and that involves more than the glycemic index. Be wary of diets that recommend extreme approaches, like eating a lot of meat or other foods that are high in saturated fat.

Cost: How much you spend depends on where you shop for groceries and the foods you buy. If you join a plan, you will have to pay the cost of packaged food.

Support: Usually you'll do this program on your own. You can get food and menu ideas in books like The Glucose Revolution or Sugar Busters!

What Dr. Arefa Cassoobhoy Says:

Does It Work?

The glycemic index diet is really not a weight loss diet. For people with diabetes who count carbs to manage their blood sugar, this diet will help you choose carbs wisely.

Keep in mind that the glycemic index diet doesn’t cover everything you eat or should eat for a healthy diet. Some higher-glycemic foods are still healthy for you, like sweet potatoes. And some lower-glycemic foods can pack a lot of calories if you eat too many, like nuts.

So while the glycemic index may guide your choice of carbs, you’ll have to decide how much of them to eat. And you’ll have to monitor how much protein and fat you're getting, as well.

There are other diet plans that remove the guesswork by putting all this information together, so those might work better for you. If you are at risk for diabetes, then incorporating the glycemic index may help you keep your blood sugars in check.

Is It Good for Certain Conditions?

It can help if you have diabetes. The American Diabetes Association recommends traditional carb counting for blood sugar control with the glycemic index information to help “fine tune” meal planning.

This diet may also help if you are insulin-resistant or have prediabetes. If you have a combination of high blood pressure, heart disease, high cholesterol, and are overweight, that may include you. Research suggests that people with insulin resistance lose weight more easily on a low-carb diet.

The added benefit of better blood sugar control is you lower your odds of getting complications from diabetes including heart, eye, and kidney disease.

The Final Word

The glycemic index diet was developed to help people with diabetes manage their blood sugar, and that’s what it’s best for. For those with diabetes or prediabetes, this diet is an important piece in the big picture of taking charge of the food you eat and staying healthy and active.

WebMD Diet A-Z

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