The Glycemic Index Diet for Dummies - Meri Raffetto [11]
People with diabetes occasionally experience hypo- or hyperglycemia. Even people without diabetes may have fluctuations in blood sugar levels that leave them feeling tired or out of sorts. Using the glycemic index to choose your foods will help you keep your blood sugar levels within a healthy range. Chapter 2 covers the role of the glycemic index in managing healthy blood sugar levels in more detail.
Using the glycemic index to lose weight can be especially helpful for people with insulin resistance (a common precursor of Type 2 diabetes). With insulin resistance, your body produces plenty of insulin, but your muscles resist the action of insulin, preventing it from doing its job (meaning your body holds onto blood sugar instead of getting rid of it). Your body keeps making more insulin in an attempt to lower blood sugar levels, and you're stuck in a vicious cycle of insulin resistance that can lead to weight gain. Follow a low-glycemic diet, and you get a cascade of beneficial effects: Your blood sugar level doesn't rise as high, which means your body doesn't need to produce as much insulin, which in turn helps your muscles use blood sugar and insulin more effectively. (Check out Chapter 5 for more about insulin resistance and the glycemic index.)
Understanding the role of carbohydrates
Food is made up of three macronutrients that contain calories:
Carbohydrates: The body's primary fuel source, providing energy for the brain, muscles, and organs.
Protein: The building block of body tissues. Rarely used for energy because it has other, more valuable uses.
Fat: Provides energy, but only when you've used up carbohydrates (that's why reducing body fat stores and losing weight is so tough).
Health experts recommend that 40 to 60 percent of a person's total calorie intake should come from carbohydrates. Admittedly, that's a wide range, but that range exists for several reasons. Active people need more carbohydrates to fuel their muscles, and children and adolescents need carbohydrates to fuel growth. On the other hand, people who are sedentary need smaller amounts of carbohydrates.
Because carbohydrates are the body's primary source of energy, it makes sense that just about every food group contains some carbohydrates. Fruits, vegetables, and grains are the primary sources of carbohydrates in foods, although milk, yogurt, and legumes also contain carbohydrates. The only food groups that contain no carbohydrates are animal meat and fat such as butter, margarine, and olive oil.
Whenever I talk about the glycemic index, I'm really talking about foods that contain carbohydrates. Plenty of misconceptions about carbohydrates are floating around, with some people thinking that all carbs are bad and that you should throw out the whole lot if you're trying to lose weight. Not true! Carbohydrates are an essential nutrient, and by using the glycemic index, you can choose foods that contain carbohydrates yet help you meet your weight goals.
The glycemic index helps you move beyond simply paying attention to the amount of carbohydrates you consume and gives you more specific information about how different types of carbohydrate-containing foods metabolize in your body and raise blood sugar levels. Because of the glycemic index, scientists know that foods that contain the same amount of total carbohydrate but have different glycemic index numbers will raise blood sugar levels differently.
Here's an example: 1 cup of dark cherries and one medium ear of sweet corn both contain 15 grams of carbohydrates. If you only count carbohydrates, you'd expect both the cherries and the corn to raise your blood sugar levels equally, right? Go one step further and look at the glycemic index of the foods individually. The glycemic index of 1 cup of dark cherries is 63, whereas the sweet corn has a glycemic index of 48. Now you know that the sweet corn will cause a lower rise