Ask the Nutritionist: Can the Glycemic Index Help Me Lose Weight?

Q. I have heard how the glycemic index is effective for weight loss. Would you agree that eating foods low in the index, in addition to protein, would assist me in losing weight and healthy eating?

A. I would agree that all people inform themselves about the glycemic index (GI), which ranks foods on the basis of how quickly they raise your blood sugar, and the newer concept of glycemic load (GL), which assesses the impact of specific amounts of carbohydrate foods on blood sugar.

On the GI, glucose is assigned an arbitrary rank of 100. Foods ranking higher than 60 are considered high GI foods. Foods ranked between 45 and 60 are moderate, and those under 45, such as cruciferous vegetables and many fruits, are considered low.

The GI doesn’t tell you how much carbohydrates are in an actual serving. The ratings are based on a serving of 50 grams of carbs. Often, you’re not going to eat that much. Carrots have a relatively high GI but you’d have to eat several pounds of them at once to get 50 grams. This is why we need the GL which takes into account the actual amount you eat. Carrots are intermediate on this scale.

The original goal of the GI was to help diabetics control their blood sugar levels. For non-diabetics, there are times when a rapid increase in blood sugar, and the corresponding increase in insulin, is desirable. For example, after strenuous exercise, insulin helps move glucose into muscle cells where it aids tissue repair.

At other times, chronic elevations in blood sugar signaling your pancreas to increase secretions of insulin can lead to a cycle of increased fat storage, lethargy and more hunger.

So although recent animal research provides compelling evidence that high-GI foods are associated with increased risk of obesity, human trials show that glycemic responses vary widely from person-to-person according to rate of insulin response, type of food, its ripeness, processing, length of storage, cooking methods, amount of food in the body and even time of day!

A much better way to control weight is by eating a variety of foods that provide bulk and volume but are relatively low in calories. They provide satiety and fullness so that you eat less but aren’t hungry. Combining all three macronutrients- carbs, protein and fat- at all meals ensures that additional fiber, protein and fat will slow digestion of the glucose and generally lower the GI and the GL of the meal.


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Judi Samuels is a Certified Nutrition Specialist & Master Personal Trainer at Bethesda Sport&Health.
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