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What happens to your body when you cut down on carbs?

Low-carb diets may be all the rage, but you may want to think twice before you drastically cut down on the number of carbohydrates you eat each day.

While limiting carbs may help you lose weight and manage blood sugar, not eating enough of the right carbs may be an unsustainable way to eat. That’s because carbohydrates are one of the three main macronutrients the body needs to function, in addition to protein and fat.

“Carbs often get a bad rap, but they’re essential to maintaining a healthy, balanced diet,” said Keri Howell, chief clinical dietician with Maury Regional Health. “It’s important to understand the difference between complex and simple carbohydrates and which ones to incorporate into your diet.”

What are some of the benefits of eating carbs?

Carbohydrates provide easily accessible energy in the form of glucose. They break down quickly and supply the body with the energy it needs to function. That energy fuels the brain, muscles and organs.

In addition to providing energy, carbohydrates play a role in maintaining the microbiome of your gut and managing other bodily functions.

Are all carbs the same?

Not at all, and this difference is what often gives carbs a bad name.

Complex carbohydrates come primarily from healthy plant foods and provide fiber in addition to loads of vitamins and minerals. Fiber helps keep blood sugar levels steadier as the foods are broken down into glucose for energy. Healthy carbs also provide special plant compounds, like antioxidants and other phytonutrients, that reduce inflammation in the body and promote a healthy gut balance.

On the other hand, simple carbohydrates, such as those from white flour and table sugar, quickly break down into glucose and spike blood sugar. They also don’t provide many other nutritional benefits.

“Simple carbohydrates are the ones you really have to watch and eat in extreme moderation,” Howell said. “It’s important to limit your intake of foods with added sugars and refined grains, like sugary drinks, desserts and candy.”

Diabetics in particular need to monitor their simple carbohydrates intake, since consuming simple carbs can cause blood glucose levels to rise quickly for those with diabetes. However, a consistent diet with complex carbohydrates is recommended to help manage this disease. 

“If you take diabetic medications or insulin to help manage your blood sugars, eating a consistent amount of the right carbohydrates throughout the day can help you achieve better glucose levels,” Howell said. “Follow up with your registered dietitian for assistance evaluating your diet and the amount of carbohydrates you eat at meals and snacks.”

What happens to your body if you don’t eat enough carbs?

While you can reap benefits by limiting the amount of simple carbs you eat, your body needs some carbohydrates to survive because it doesn’t make them itself. The best types of carbohydrates to consume are those from fruits, vegetables, whole grains and legumes. If your body doesn’t get enough carbohydrates, you may experience the following side effects:

  • You may feel sluggish. Many people find they feel tired and don’t have much energy when they don’t eat enough carbs. That’s because carbs are the body’s main energy source.
  • You may find it harder to concentrate. About 20% of the energy required by the body fuels the brain. If your body doesn’t have an easily accessible source of energy in the form of glucose, it has to break down fat into ketones for energy. This may make it harder to concentrate and make decisions. You may also experience headaches and may feel weak or dizzy, especially as your body adjusts to the change of energy source.
  • You may have bathroom difficulties. The foods that are the best sources of carbohydrates are also the best sources of fiber. Eating enough fiber is important for bathroom regularity, and people who don’t get enough may experience constipation. Fiber promotes the growth of healthy bacteria in the gut, so you may also experience other gastrointestinal issues.
  • Your eating plan may not be sustainable. Severely restricting or cutting out entire food groups can be difficult to maintain over the long term. Unless it has been recommended that you cut out carbs for a medical reason, consider making small adjustments to your diet if you’re trying to lose weight and eat healthier so that the changes you make are ones you can live with.

Maury Regional Health offers nutrition counseling with a team of registered dietitians who work alongside patients and their primary care providers to set goals based on the patient’s unique needs. Consultations may be offered on a one-time or recurring basis, depending on the physician’s recommendation.

Nutrition counseling is offered with a physician’s order. For more information, call 931.381.1111, extension 1275, or visit MauryRegional.com/NutritionCounseling.


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Date Last Reviewed: September 14, 2023
Editorial Review: Andrea Cohen, Editorial Director, Baldwin Publishing, Inc. Contact Editor
Medical Review: Jane Schwartz, RDN, CLT
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