Low Glycemic Foods and Diabetes

The term “Glycemic Index” is getting a lot of play, but most people don’t understand exactly what it is. While it sounds like something having to do with forecasting the weather, playing the stock market, or finding a book at the library, it’s actually a nutritional term, and can be an important part of understanding how to eat well.

The Glycemic Index, or GI, is a tool designed to help guide food choices. It rates carbohydrates and how the body reacts to them after eating. Originally developed as a means to help diabetics manage their blood sugar, it’s been more widely researched in recent years to achieve certain health benefits through better eating.

This investigation is relatively new; experts continue to evaluate the impact of GI-based diets on improving people’s wellbeing. Nevertheless, many agree that positive nutritional results can be achieved by using the Glycemic Index to evaluate food choices. Low-GI foods are thought to keep blood sugar low and steady. That’s a good thing and here’s why.

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Scoring your food

At the crux of the GI is a point system that ascribes a score to any carbohydrate-containing food. This is because not all carbs are created, digested, or enter the bloodstream equally. If an item doesn’t contain carbs — like, for example, animal proteins, nuts, herbs, spices, and oils — it’s not classified on the GI. This numerical value is based on nutrient composition, ingredient mix, cooking method, ripeness, and amount of processing. Once assigned, the GI then ranks foods according to how much they raise a person’s blood sugar or glucose. The lower the score — which can range from 0 to 100, with pure glucose arbitrarily given the value of 100 — the better its impact on blood sugar.

In practice, foods with a lot of refined carbs and sugar often rate high (greater than 70) on the GI because they’re digested quickly and tend to spike blood sugar and insulin, the hormone that helps glucose get into cells. They’re also metabolized quickly, which makes them less satiating, meaning you get hungry faster. Foods with fewer refined carbs and sugar, and more protein, fat, and fiber, typically have a lower GI rating (under 55). Since they’re digested, absorbed, and metabolized more gradually, they cause a lower and slower rise in blood glucose, insulin, and are more satiating – you get hungry more slowly. This is why some believe that low-GI foods may have a place in weight loss. This can help diabetics manage unwanted surges and swings in blood sugar that affect mood, energy, and a number of other things. It also can help lower the risk for people struggling with pre-diabetes.

Many experts also agree that eating a diet of low-GI foods can be useful for people who want to make more holistic improvements, too. Low-GI foods are whole foods, less processed, and more complex in carbohydrate, and they can also help support weight loss, lower cholesterol, reduce risk of coronary disease and some cancers, and even improve eyesight, mood, and energy.

Adopting a low-GI approach

If you think a low-GI diet it might be right for you, you’ve got options. You can choose to follow the advice of commercial books, websites, and diets that have embraced the low-GI approach, such as the Zone Diet and the Slow-Carb Diet. Or you can also go it on your own by following some basic rules:

  • If you’re not sure how a food is scored, use an online tool or app to figure that out. There are lots out there. Here are a couple to get you started:
  • Aim low. Set a goal of eating foods that average between 45 and 55 on the GI. They typically include whole, unrefined, and organic options like fruits and vegetables, and no- to low-fat dairy. Include no-GI foods for balance, including those mentioned earlier, like meat, poultry, fish, nuts, oils, seeds, herbs, and spices.
  • Don’t assume. Calculating where a food falls on the GI can be nuanced, especially when you consider that an English muffin made with white wheat has a GI value of 700, and a value of 45 if it’s made with whole wheat.
  • Swap out high GI foods for lower GI alternatives. To be clear, low GI foods generally include low-sugar options, like apples and berries; non-starchy vegetables like broccoli and carrots; whole grains like quinoa and oats; and legumes like lentils and black beans. Higher GI options include more processed foods, like breads, starchy rice, pasta, and vegetables (potatoes, corn), baked goods, and sugar-sweetened beverages.
  • Consider your “Glycemic Load” or GL. In simple terms, the GL, which is different from the GI, has you think about how much you’re eating and combinations of foods – not just what you eat, but how those foods interact together. Success on a GI-based diet, or any diet, is not about one single food, but your meals, too. Think carefully about how much you eat in totality. Yes, this is complex, so reach out to a registered dietitian nutritionist for guidance.
  • Embrace common sense. Use your best judgment when it comes to portion sizes and calories consumed since low-GI diets are often not prescriptive in this area. Keep in mind that the blood-sugar response to foods can vary widely from person to person, and that the numbers don’t always tell the whole story. After all, potato chips have a GI score of 54, and a Snickers bar has a 55. GI is one more important attribute about a food, not a magic bullet.

While a low-GI approach can be helpful, it also requires a certain amount of precision and know-how to do it right (not unlike forecasting the weather, buying stocks, and even navigating several floors of books). If you’re intrigued, it might be worthwhile to enlist the advice of a registered dietitian who can help you not only understand how the diet works, but how to customize it for achieving your wellness goals.

March 2021

Additional Resources

Glycemic index diet: What's behind the claims
About Glycemic Index
Type 2 Diabetes Are you at risk?