How to Make the Right Carb Choices

By Richard Asa and Temma Ehrenfeld @temmaehrenfeld
December 14, 2022
Studio portrait of senior man smiling --- Image by © Norbert Schaefer/Corbis

What is a carbohydrate? And why are some carbs good for your health and others bad for you? The answers lie in a food's balance of sugar and other nutrients.

Many people are trying to eat far fewer carbohydrates, especially those carbs nutrition experts say are bad for us.

To make choices even harder still, there’s the glycemic index (GI), which classifies carbs based on how much and how fast they spike your blood sugar and insulin.


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What are carbs?

Simply put, carbohydrates provide the energy we need to conduct our everyday lives. You need them in your diet. Otherwise, your cells run on a draining battery.

Your brain, nervous system, and muscles need carbs for nourishment. In your body, the predominant carb is glucose. In your blood, glucose, sometimes called blood sugar, is the main energy source.

The simplest carbs are sugars, which include glucose, fructose, lactose, and sucrose. More complex carbohydrates, including starches, are made up of strings of sugar molecules bound together.

Complex carbs, which nutritionists recommend you eat, raise your blood sugar level more slowly than simple carbs. Examples include peas, beans, non-starchy vegetables, and whole grains. Simple carbs provide sugar with fewer nutrients or fiber. Healthy simple carbs include milk and fruit.

Foods that raise your blood sugar level more quickly are especially bad for you if you have (or are at risk for) obesity, type 2 diabetes, heart disease, and cancer.  They are also associated with weight gain, which in turn increases your risk of those diseases.

The effect of the glycemic index

There is no question that people with high blood sugar after eating are at risk for more disease, especially heart disease. Age, ethnicity, and family history make a big difference in how your body processes sugar.

But you can improve your body’s blood sugar system: Lose extra pounds, increase your physical activity and lean muscle, and improve your sleep. Eating low-glycemic index foods will also help.

On any given day, the carbs you eat determine your blood sugar after a meal. A low-fat, high-carb meal raises it more than a low-carb, high-protein, or high-fat meal.

There is also a huge range in the impact of different kinds of carbs. Agave syrup has a glycemic index (GI) of 11, compared to Thai jasmine rice with a GI of around 100 (and it’s just as sweet as pure sugar). The lower the GI score a food has the better.

It’s important to realize that a baked white potato (with a GI of 111, even more than the rice or eating sugar) isn’t much better for you than a candy bar. On the other hand, if you want something sweet and starchy, a microwaved yam has a GI of around 70.

If you have type 2 or type 1 diabetes, your doctors will advise you to count carbs, keeping track of the carbs you eat and checking your before- and after-meal blood sugar.

About a third of U.S. adults under 44 have prediabetes, meaning their bodies work harder than they should to process sugar. That figure jumps to 37 percent for older adults. This group can also benefit from losing weight and watching carbs to avoid developing diabetes.  

In general, when you lower your total carb consumption, you lower cardiovascular risk factors like cholesterol, triglycerides, and blood pressure.

The best recommendation is to eat more whole grains, beans, fruits, and vegetables, while cutting back on highly processed and sugary foods and drinks. If you follow that advice, you’ll tend to lower your glycemic load. The overall nutritional quality of your meals may be more important than the GI value of each food item.

Good food for people with diabetes

To wade through the information out there without feeling like you’re sinking in dietary quicksand, aim for foods rich in fiber, vitamins, minerals, and phytonutrients (typically non-processed foods).

Ideally, they will help you feel full and not overeat. If you want a piece of bread, try a thick rye bread, which might have a GI below 46, compared to 77 for ordinary white wheat. Rolled oats have a GI of around 55, compared to 80 for instant oatmeal and up to 87 for cornflakes.

Sometimes you eat just to eat, and for Americans that often means readily available and highly-calorie cheap junk foods with little nutritional value. The less often you give in to these temptations, the better.

What you can do

Spending some time looking at the GI index of various foods will help you identify the foods that are busting your waistline and blood sugar health. There’s evidence that lowering the GI of your overall diet will help you lose weight and keep it off.


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December 14, 2022

Reviewed By:  

Christopher Nystuen, MD, MBA and Janet O'Dell, RN