- Low-glycemic and low-carb diets are often confused, but there are differences.
- Both have similar benefits, and which is healthier depends on your needs and goals.
- Very-low-carb diets are not recommended for many reasons.
Millions of Americans go on a diet each year for various reasons, whether it’s to better manage a health condition or simply a desire to feel better. Two diets that have held the spotlight for some time and have had countless studies published on them are often confused: the low-glycemic diet and the low-carb diet. While both aim to improve health, each comes with a unique set of differences, and determining which one is healthiest depends on your goals and which one will be most sustainable for you to do long-term.
What Is the Low-Glycemic Diet?
If you’ve even been told to start watching your carb intake due to an elevated HbA1c—a three-month average of your blood sugar—you may have stumbled across the low-glycemic diet. The low-glycemic diet doesn’t require you to cut carbs, but it does emphasize choosing low-glycemic foods over high-glycemic foods. Foods that contain carbohydrates—anything from an apple to a bowl of pasta salad to a cookie—are all rated with a value from 0 to 100 on the glycemic index.
Foods with a low glycemic index (GI) of 55 or less are mostly fruits, vegetables, beans, yogurt and nuts. These are deemed to be low-glycemic foods and are given the green light to regularly add into your eating pattern. On the other hand, foods considered high GI are those with a GI of 70 or higher. These foods include things like baked goods, white rice, white bread and certain cereals.
Foods with a high GI can cause your blood sugar to spike and then quickly fall, which is why they should be enjoyed in a more limited way. A food with a low GI will help keep your blood sugar levels stable and may help you lose weight, improve your energy levels and reduce your risk for certain health conditions, including diabetes.
However, this approach comes with limitations. For one, the low-glycemic diet doesn’t look at a food as a whole, and some highly nutritious foods have a high glycemic index. For example, watermelon has a GI of 70; however, this juicy fruit is low in total calories, high in antioxidants and water, and most dietitians would agree it’s a good choice for many healthy eating patterns. The low-glycemic diet also has a strong emphasis on portion sizes, which can be easy to misjudge, plus not all foods are listed on the glycemic index, so you might be left stumped when you cannot find a specific GI number for your favorite food.
It’s also important to point out that most of the time, we also eat foods in combination with other foods. So for example, if you eat only watermelon, you might get a spike and then crash of blood sugar. But if you eat your watermelon with a handful of nuts or some cheese, the fat and protein in them will help stabilize blood sugar. This is why it’s not necessary to only eat low-GI foods; it is wise, however, to pair higher GI foods with protein and fat.
What Is the Low-Carb Diet?
The diet that puts a cap on the amount of carbs you can eat each day is a low-carb diet. The low-carb diet has become so popular that there are many variations of it, such as the Atkins diet, Whole 30 and the South Beach Diet—all of which emphasize low-carb intake. But some of these diets are fad diets and come with their own set of diet rules.
In general, the low-carb diet limits your total carbohydrate intake to a percentage of your total daily calories or provides a specific total gram amount to consume each day. Some sources define a low-carbohydrate diet as one that gets less than 26% of your daily calories from carbs, or less than 130 grams of total carbs per day. The goal of this diet is to assist with weight loss and help manage blood sugar levels.
It’s important to differentiate low-carb diets from very low-carb diets. For example, the keto diet is very low carb, allocating less than 10% of total calories to come from carbs, or approximately 20 to 50 grams of carbs per day. To put this into perspective, one medium banana contains 27 grams of carbohydrates.
Here at EatingWell, we recommend that you don’t drop below 40% of your calories from carbs, or go below 120 grams of carbs per day. Drastically reducing your carb intake may prevent you from consuming sufficient vitamins, minerals and fiber found in carb-rich foods like fruits, veggies, whole grains and legumes. While reducing carbs some may be beneficial for you, we do not recommend going very low-carb. For example, excessively loading up on certain foods frequently recommended on keto diets—like bacon and cream cheese—may have adverse effects on heart and digestive health if consumed in excess over time.
Which Is Healthier?
So, which diet—the low-glycemic diet or low-carb diet—is the healthier option? It depends on your individual needs.
The low-glycemic diet may be favorable for cholesterol and blood sugar control, specifically for those living with or at-risk for diabetes. For example, a meta-analysis found the low-glycemic diet was effective in lowering blood sugar levels and slightly reducing body mass. And another systematic review and meta-analysis found that a low-glycemic diet did a better job than a high-glycemic diet at improving a key metric that measures insulin resistance in adults without diabetes. With that said, researchers do note that it may be less about where a food ranks on the GI scale and more about the fact that low-GI foods tend to be highly nutritious, including being high in fiber.
On the flip side, the low-carb diet has been touted for its weight-loss benefits, plus better glycemic control in people with diabetes. When comparing low-carb to low-fat diets, there is evidence that suggests there’s not much difference regarding weight loss. Researchers also saw no difference in health benefits, including blood sugar or cholesterol levels, when comparing low-fat and low-carb diets.
Another reason to avoid very low-carb diets is that they may hamper your mood. One meta-analysis found that a low-carb diet significantly increased anxiety when participants’ diets contained less than 26% carbs. The American Heart Association also ranked low-carb and very low-carb diets, such as the keto diet, at the very bottom of their list for diets that promote heart health.
Since the term “healthier” is relative, determining which one is healthier—low-glycemic or low-carb—depends on which one is more sustainable for you and what your goals are. If you’re looking for some guidance to get started, whether you want lower glycemic foods or lower carbohydrates—without sacrificing flavor and satiety—then try our 30-Day No-Sugar, High-Fiber & High-Protein Meal Plan.
Our Expert Take
Both low-glycemic and low-carb diets have potential for weight loss and lowering blood sugar, though some find a low-glycemic diet less restrictive than a low-carb diet. We recommend avoiding very low-carb diets for many reasons, including that they may negatively affect mood, have not been shown to promote heart health and aren’t sustainable long term.
As a registered dietitian, I am not one to promote fad diets or any one specific diet. Diets have limitations and downfalls, and what might work for you may not work for someone else. Nutrition is personal and each person has a unique set of needs, medical history, food preferences and goals that need to be taken into consideration before implementing any type of meal plan. Consulting with a registered dietitian before starting any diet or meal plan is always recommended.
