There has been a lot of discussion about low carbohydrate (“low carb”) diets in recent years. Many people have turned to a low carb diet for weight loss. However it is important to have at least a basic understanding of how low carb diets work to prevent harmful side effects and weight regain.
Low Carb Diets: The Basics
Carbohydrates, or carbs, are one of the three macronutrients (“building blocks”) found in our food. Carbs serve as a quick energy source compared to fat and protein, the other two macronutrients. There are three types of carbohydrates: starch, fiber, and sugars. Starch and fiber are complex molecules mostly found in plant sources. Fiber in particular takes more energy to break down; thus fiber is considered to be a “healthy carb,” unlike sugars. Most of the information about what to eat on a low carb diet focuses on a high protein, low sugar and low carb diet.
Excess sugar intake has been linked to obesity and diabetes. Most Americans consume excess sugar given that the daily recommended intake of added sugar is less than 50 grams per day. Even if you aren’t on low carb diet, it is beneficial to reduce your sugar intake.
Low Carb Diet vs. “Keto” Diet
A low carb diet consists of consuming 60-130 grams of carbs per day. A ketogenic diet, or “keto diet,” is a very low carb diet. A keto diet involves decreasing carb intake to a level that forces your body to use fat instead of carbs to generate energy. The fat utilization process is called ketogenesis and occurs when you eat less than 50 grams of carbs per day. This leads to your body being in ketosis. Ketogenesis is not the same as ketoacidosis, which is a harmful medical condition in which the body generates too much acid.
Side Effects of a Low Carb Diet
Americans generally consume more carbs than needed for a healthy diet. Carbs can safely be reduced without significant side effects if not lowered too low (less than 60 grams of carbs per day). A very low carb diet, such as ketogenic diet, will generate side effects. The initial symptoms of “carb withdrawal” or “keto flu” are usually fatigue, headaches, hunger, constipation, or diarrhea. Ketogenesis can also cause dehydration, electrolyte changes, gout flares, gallstones, and in extreme cases, heart irregularities. For this reason, people following very low carb diets should be medically monitored, especially if they have a chronic medical condition.
Weight Loss and the Low Carb Diet
A low carb diet can produce significant weight loss very rapidly (within weeks to months), especially compared to a low fat diet. However, few studies have shown lasting weight loss with the low carb diet past one year. As with any significant weight loss, the body naturally tries to regain weight. A trained obesity medicine specialist or weight loss clinician can help with strategies to sustain weight loss. The Obesity Medicine Association has trained clinicians in your area that can help you with weight loss and improvement of overall health.
- Nordmann AJ, Nordmann A, et al (2006) Effects of low-carbohydrate vs low-fat diets on weight loss and cardiovascular risk factors: a meta-analysis of randomized controlled trials. Arch Intern Med. 2006;166(3):285
- Perreault, L (2018). Obesity in adults: Dietary Approach. Up To Date. Retrieved from: https://www.uptodate.com/contents/obesity-in-adults-dietary-therapy?search=low%20carb%20diet%20obesity&source=search_result&selectedTitle=1~150&usage_type=default&display_rank=1#H10 on July 23, 2018
- Mayo Clinic Staff (2017). Low-carb diet: Can it help you lose weight? Retrieved from: https://www.uptodate.com/contents/obesity-in-adults-dietary-therapy?search=low%20carb%20diet%20obesity&source=search_result&selectedTitle=1~150&usage_type=default&display_rank=1#H10 on July 23, 2018
This article was written by Sylvia Gonsahn-Bollie, MD. Dr. Gonsahn-Bollie is an internal medicine and obesity medicine physician in Richmond, VA. She is a Diplomate of the American Board of Obesity Medicine.