Everything You Need to Know About Eating a Low-Glycemic Diet

The glycemic index measures how quickly your blood sugar rises after eating a food. Foods are ranked from 0 to 100 based on how they affect your blood sugar.

Foods that are digested quickly and spike blood sugar levels have the highest GIs. In contrast, foods that take a while to digest and slowly release insulin into your bloodstream have lower GIs. A low GI is less than 55, and a high GI is 70 or higher.

The GI of a food is largely dependent on the type of carbohydrate it contains — the higher the fiber content, the more slowly the food digests.

Lower-GI foods usually have more protein, fiber, and sometimes fat.

“Eating lower-GI foods can definitely be beneficial for many people — particularly because many of the foods that are lower glycemic index also tend to be higher in protein and/or fiber, as well as higher in nutrients. For example, an egg is one food that has a low glycemic index and provides 6 grams of satiating high-quality protein, as well as choline and the carotenoids lutein and zeaxanthin,” says Amy Gorin, MS, RDN, owner of Amy Gorin Nutrition.

Here’s another important tidbit: It’s a common misconception that all foods with sugar have a high GI.

For example, bananas, which many people think of as a high-sugar fruit, are low-GI, with a score of 51. Not surprisingly, processed carbs — like white bread, chips, pretzels, desserts, and soda — rank highest in GI.

It’s also essential to remember that GI doesn’t necessarily determine a food’s overall healthfulness. For example, white potatoes and watermelon are high-GI foods, but we know they have nutritional value in a balanced diet.

The key to following a low-GI diet is to choose mainly low-GI foods but consciously fill in the gaps with nutrient-rich, whole foods that create a balanced meal plan. The easiest way to do this? Make an appointment with your doctor, nutritionist, or dietitian.

The low-GI diet was originally created to help people with diabetes manage their blood sugar. And research has shown that it can help control post-meal blood glucose spikes.

For people with prediabetes or a family history of diabetes, eating a low-GI diet can help keep the disease at bay. A 2014 review concluded that people eating a high-GI diet have a 33 percent higher risk of developing diabetes than those who eat low-GI.

There’s even research to suggest that sticking to low-GI foods can help you shed pounds. A six-month controlled trial showed greater reductions in BMI in participants who followed an LGID.

Another benefit of taking it low? Reduced risk of heart disease. High LDL or “bad” cholesterol is a symptom of heart disease, and a 2013 review found that low-GI diets significantly reduced total LDL cholesterol, especially when the participants increased their fiber intake.

If you want to try a low-GI diet, add these low-GI foods to your shopping list:

Fruit and veg

• apples
• dates
• grapefruit
• mango
• oranges
• peaches
• pears
• carrots
• corn
• green peas
• leafy greens
• parsnips
• sweet potatoes
• tomatoes

Proteins*

• beef
• chicken
• fish
• shellfish
• turkey

Beans and legumes

• black beans
• black-eyed peas
• chickpeas/hummus
• kidney beans
• soybeans

Grains

• barley
• brown rice
• bulgur
• oats/oatmeal
• quinoa

Dairy and faux dairy

• greek yogurt (check those labels, though)
• milk
• soy milk

Other*

• avocado
• herbs and spices
• nuts
• oils

*To be fair, these foods are low enough in carbohydrates that they don’t actually rank on the GI. Nevertheless, they are part of a balanced diet, so we’re including them.

These foods rank at 70 or higher, so stay away:

• bagels
• instant oatmeal
• mashed potatoes
• most cereals
• most cookies (we know, we’re crying, too…)
• pretzels
• rice crackers
• rice milk
• soda
• waffles
• watermelon
• white bread
• white potatoes
• white rice

Some foods fall in the gray area and can be eaten once in a while on a low-GI diet:

• couscous
• grapes
• honey
• pineapple
• popcorn
• pumpkin (but no PSLs — unless they’re this version)
• Raisin Bran cereal
• raisins
• rye bread

“People with diabetes or prediabetes may benefit from a low-GI diet,” says Gorin. Those with a history of heart disease may also want to give this diet a try.

“But keeping track of the glycemic index of foods can take a big commitment, so a low-GI diet may not be ideal for people who prefer to follow a more cut-and-dry meal plan,” she says.

• Just like any other diet, a low-GI diet isn’t a cure-all. It’s a commitment to choosing certain foods that may help prevent conditions like diabetes or heart disease. The amount of food eaten is also important — just because a food has a low GI doesn’t mean it’s a free-for-all.
• Following a low-GI diet takes dedication, but it’s definitely doable with a bit of planning and guidance. Cooking methods and the combination of other foods at a meal can change the GI of a food. Adding a little healthy fat, like olive oil or avocado, can lower the GI, while cooking or blending a food may increase the GI.
• If you think this diet could be right for you, ask your doctor and meet with a registered dietitian to get started.