The Long-Term Risks of Low-Carb Diets

Some medical professionals have questioned the safety of low-carb diets.

Low-carb diets are popular and controversial at the same time. When not used with proper overall nutrition in mind, a low-carb diet can potentially lead to long-term health effects. Among those are an increased risk for gout, a form of arthritis, and osteoporosis.

healthy keto breakfast: egg, avocado, cheese, bacon
OlgaMiltsova / Getty Images

Popular Diets

Low-carb diets come in many varieties, and the buzzwords "low carb" are found on many food labels.

Low-carb diets that have generated a lot of publicity include:

  • Atkins Diet
  • Carbohydrate Addict's Diet
  • South Beach Diet
  • SugarBusters!
  • Zone Diet
  • Paleo Diet

The publicity has been both favorable and unfavorable. Reports of short-term weight loss success and improved levels of good cholesterol (HDL) and triglycerides are common. On the other hand, reports of potential negative health consequences show the downside of these diets.

Some physicians, nutritionists, researchers, and other healthcare providers have questioned the safety of low-carb diets.

How They Work

The basic concept behind a low-carb diet is that carbohydrates promote insulin production, which in turn promotes the accumulation of fat.

The theory is:

  • A lower daily intake of carbohydrates causes the body to burn stored carbohydrates for energy.
  • As this process of burning stored carbohydrates (a.k.a. glycogen) occurs, water is released and weight loss follows.
  • The body also begins to burn fat for energy.

Such a diet is called a "ketogenic" diet because it causes an accumulation of ketones (byproducts of fat oxidation) in the bloodstream, which are removed by the kidneys.

In a state of what has been called perpetual ketosis or benign dietary ketosis, a person loses weight no matter how many calories are consumed from fat and protein.

Long-Term Health Effects

The long-term risks and consequences of a low-carb diet are being researched and no definitive or conclusive evidence yet exists.

Compared to national guidelines for nutrition and weight loss, some low-carb diets contain high amounts of saturated fat, animal protein, and cholesterol. At the same time, they lack nutrients, fiber, and complex carbohydrates considered necessary for maintaining good health.

Health experts who express concern over long-term safety suggest some low-carb diets may increase the risk of certain diseases such as:

Low-Carb Diets and Gout

Gout is one of the most painful types of arthritis. The suggested correlation between a low-carb diet and an increased risk of gout seems obvious.

Gout is caused by an excess of uric acid in the body. Foods rich in purines (i.e. meat, poultry, seafood, nuts, eggs, etc.) are later broken down into uric acid in the body. Since many low-carb diets emphasize fat and protein, especially from animal sources, people following a low-carb diet may eat enough purine to trigger a gout attack.

Low-Carb Diets and Osteoporosis

Osteoporosis is a condition that is characterized by loss of the normal density of bone, resulting in brittle bones, which are subject to fracture. The disease process can be silent (without symptoms) for decades.

There is a potential increased risk of osteoporosis with a low-carb diet where calcium loss can result if protein intake remains high and calcium intake remains low. The ratio of animal to vegetable protein intake may also contribute to bone loss. While research in rats and mice has shown losses in bone density associated with low-carbohydrate diets (as in this 2017 study, for example), small studies in humans have not supported the association.

Benefits of a Low-Carb Diet

While carbohydrates can be an important part of a healthy diet, some carbohydrates can be healthier for you than others. You can help improve your health by limiting simple refined carbs that aren't good sources of fiber and nutrients.

Simple refined carbohydrates, sometimes called "bad carbs," are the ones found in foods like white bread, white rice, pasta, and pastries. These simple carbs break down easily and can lead to a rapid increase in blood sugar. Eating too many of these carbohydrates can lead to weight gain and increase your risk of health conditions like diabetes.

Not all foods with simple carbs are bad for you, though. Simple carbs can also be found in whole foods that provide vitamins, minerals, and fiber that your body needs. These include fruits, vegetables, and dairy foods.

Complex carbs, also known as "good carbs," are digested slowly so your blood sugar rises more gradually. They can be found in whole grains, like brown rice and oatmeal, which help protect against diabetes and heart disease.

Studies show that eating a moderately low-carb diet can help improve heart health if protein sources are low in saturated fat.

A Word From Verywell

As is evident by analyzing the prevalence of obesity data, weight loss is a significant issue. However, it is important to realize that not all diets are healthy and some may have serious long-term health consequences. 

You should discuss your overall health situation with your healthcare provider before choosing a weight loss plan. Together, you can review your personal health history and options so you can do your best to avoid adverse effects of a particular weight loss plan.

Frequently Asked Questions

  • What does a low-carb diet do to your body?

    Your body usually uses carbohydrates as a source of energy. When your body doesn't have enough carbs, it breaks down fat for energy. This produces a substance called ketones, which become a fuel source for the body.

  • What are the side effects of a low-carb diet?

    You might experience flu-like symptoms, including upset stomach, headache, dizziness, and fatigue. You might also experience constipation if you're not getting enough fiber in your diet.

  • Do we need carbs to survive?

    You may be able to survive without eating carbs, but it would have negative effects on your health. Most vegetables and fruits have some carbs, so cutting from your diet would eliminate nutrients and fiber your body needs. You may experience side effects and a higher risk of health conditions from eating an unbalanced diet.

10 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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  2. Gershuni VM, Yan SL, Medici V. Nutritional ketosis for weight management and reversal of metabolic syndrome. Curr Nutr Rep. 2018;7(3):97-106. doi:10.1007/s13668-018-0235-0

  3. Brouns F. Overweight and diabetes prevention: is a low-carbohydrate-high-fat diet recommendable?. Eur J Nutr. 2018;57(4):1301-1312. doi:10.1007/s00394-018-1636-y

  4. Academy of Nutrition and Dietetics. Children need carbohydrates.

  5. Lockyer S, Stanner S. Diet and gout - what is the role of purines?. Nutr Bull. 2016:41(2):155-166. doi:10.1111/nbu.12205

  6. Zhang Y, Chen C, Choi H, et al. Purine-rich foods intake and recurrent gout attacks. Ann Rheum Dis. 2012;71(9):1448-53. doi:10.1136/annrheumdis-2011-201215

  7. Hu T, Yao L, Bazzano L. Effects of a 12-month low-carbohydrate diet vs. a low-fat diet on bone mineral density: A randomized controlled trial. FASEB J. 2016;30(1_supplement). doi:10.1096/fasebj.30.1_supplement.678.12

  8. Nemours Foundation. KidsHealth. Carbohydrates and sugar.

  9. Harvard T.H. Chan School of Public Health. Low-carbohydrate diets. The Nutrition Source.

  10. Academy of Nutrition and Dietetics. What is the ketogenic diet?

Additional Reading

By Carol Eustice
Carol Eustice is a writer covering arthritis and chronic illness, who herself has been diagnosed with both rheumatoid arthritis and osteoarthritis.