The glycemic index: good carbs, bad carbs
If you’re one of those people who can’t stand all the counting, tracking, adding, and recording that some diets require, you can find refuge on a simple numerical scale: the glycemic index. On the other hand, you may find it another maddening way to complicate the simple act of eating.
The glycemic index is a measure of the quality of carbohydrate foods. It is a kind of good carbs / bad carbs, depending on how they affect your blood sugar level. Although not new, it started to get a lot of press when the anti-carb movement took hold.
Here’s how it works: On the glycemic index, pure glucose is arbitrarily assigned a score of 100; it doesn’t mean anything in particular; it’s just an established benchmark of how your blood sugar has affected about two hours after eating. Then, all the other foods in the index are assigned a number relative to glucose and its effect on blood sugar.
Foods with a low index generally break down slowly and do not cause drastic fluctuations in blood sugar. Foods with a high index usually are. For example, green peas have an index of 39, while cornflakes have an index of 92.
Originally developed to help people, particularly diabetics, control their blood sugar, the index primarily includes carbohydrate foods, because protein and fat don’t have much of an immediate effect on blood sugar.
But assigning numbers to different foods based on their glycemic effect simply creates an escalating list of foods that ends up being a very useful tool for people who are also dealing with obesity and other health problems. This is because simply sticking to a low glycemic index diet tends to guide people toward healthier eating and weight loss, even when that’s not their specific goal.
Consider: Type II diabetes, as well as various cancers and cardiovascular diseases, are highly correlated with high-index diets. There is plenty of research showing that lowering the overall glycemic index also reduces the risks of these problems.
This is because, almost by default, a low-index diet will include more fresh fruits and vegetables, more fiber, more dairy – all foods that offer essential nutrients, that are more likely to be lower in calories, and that tend to to keep the body satiated for longer. , delaying the next hunger spell. All of that generally adds up to weight loss, regardless of the program.
Proponents of the index say it is more useful than counting calories or grams of fat or carbohydrates, and it actually offers a simplified approach to learning how to eat better, but some experts caution that people shouldn’t worry too much about precise numbers. Instead, they urge people to pay attention to whether the foods they eat have a low, medium, or high index.
That’s because, as with any rule, there are exceptions to the fairly consistent physiological rules underlying the index. For example, watermelon has a fairly high glycemic index, around 75, which is even higher than table sugar. Does that make it bad for you? No. Because despite its high index, watermelon actually has a fairly low glycemic load. That’s a measure based on how much food you’d actually eat, not just an arbitrary amount used in testing, like with the index.
The glycemic load of a food can be determined using the glycemic index number of a food, divided by 100 and multiplied by the available carbohydrates that you would consume. With most foods, a low index is consistent with a low load, but there are wacky exceptions. Of course, to find them, you’d do a lot of math again, and that’s not the way people normally eat.
That’s why doctors and nutrition experts encourage people who are trying to develop a healthy diet to avoid getting caught up in the numbers game and to look more generally at the foods in the index, leaning towards those that are at the lower end. Anything above 70 is considered high index, 55-69 is medium, and below 55 are low glycemic index foods.
And look at what’s in those groups: High-index foods include most breakfast cereals, white breads, and other processed baked goods, most potatoes, ice cream, candy, and table sugar – your true nightmare of Atkins.
The lowest index foods include cherries, grapefruits, broccoli, legumes like lentils and beans, most whole-grain baked goods, and most dairy products. So even without counting calories or keeping track of specific index numbers, you can see that pushing your diet towards the lower end of the index is sure to do you good.
We like to encourage patients to think of the glycemic index and glycemic load as two more tools that can be helpful in developing healthier thinking and planning about eating habits.
One last thing to remember: there is no standardized list of glycemic indexes, and most indexes include brand-name items that people buy on a typical shopping trip, as well as more generic items like vegetables and fruits. This is one of the most useful aspects of lists, but only if you get one that relates to where you live.
If an average Southwest Florida resident looked at an index created in Australia, it wouldn’t be of much help, because really, when was the last time you had a couple of Golden Pikelets with a nice glass of Milo?
THROUGH THICK AND THIN
Fruits tend to have a high glycemic index, so I recommend that people eat their fruits with a meal or with some protein like cottage cheese or regular cheese. These protein sources help mitigate the glycemic effect of fruits. Don’t let a high index keep you away from your apple a day.
