At this point, most people have heard of, considered, or perhaps even tried a ketogenic diet to lose weight and become healthier. The diet’s recent popularity has led many to wonder if it is nothing more than a pseudoscientific fad, or if it is actually safe and can improve health. Lucky for us, the ketogenic diet was created in the 1920s, long before the Atkins diet, South Beach diet, and many other popular diets, so there is a good amount of research and historical information about ketogenic diet safety, effectiveness, and risks.
What are ketogenic diets?
Ketogenic diets restrict carbohydrates—sugar, starch, and fiber—to less than 20–50 grams per day. That range sits far below the recommended 225–325 grams per day from The Dietary Guidelines for Americans.1Carbohydrates: How carbs fit into a healthy diet. Mayo Clinic. 2017. https://www.mayoclinic.org/healthy-lifestyle/nutrition-and-healthy-eating/in-depth/carbohydrates/art-20045705 For reference, a large apple has ~23 grams of sugar. The low dietary intake of carbohydrates under a ketogenic diet forces our bodies to convert other fuel sources, such as proteins and fats, into ketone bodies that fuel our organs, like our brains. This process is called ketogenesis and is critical because our organs cannot directly use proteins or fats as fuel.
Recently, ketogenic diets have been shown to promote weight loss and improve type 2 diabetes in overweight and obese patients, spurring its popularity.2Ministrini S, Calzini L, Nulli ME, et al. (2019). Lysosomal acid lipase as a molecular target of the very low carbohydrate ketogenic diet on morbidly obese patients: the potential effects on liver steatosis and cardiovascular risk factors. J Clin Med. 8(5). https://www.ncbi.nlm.nih.gov/pubmed/310678243Paoli A, Rubini A, Volek JS, Grimaldi KA. (2013). Beyond weight loss: a review of therapeutic uses of very-low-carboydrate (ketogenic) diets. Eur J Clin Nutr. 67(8): 789-96. https://www.ncbi.nlm.nih.gov/pubmed/23801097
Are ketogenic diets safe?
Generally speaking, yes. A lot of historical evidence shows that long-term adherence to ketogenic diets has minimal side effects, though it may feel uncomfortable in the beginning.4Groesbeck DK, Bluml RM, Kossoff EH. (2006). Long-term use of the ketogenic diet in the treatment of epilepsy. Dev Med Child Neurol. 48(12):978-81. https://www.ncbi.nlm.nih.gov/pubmed/17109786 When switching from a regular western diet to a ketogenic diet, many people experience a “keto flu” with symptoms such as fatigue, nausea, and even muscle cramps. This happens because the body initially can’t get enough energy from the ketogenic diet. While it may feel bad at the time, these symptoms usually resolve after a week as the body makes enzymes to promote ketosis. More importantly, there are well recognized common side effects of ketogenic diets, such as kidney stones.5Hartman AL & Vining EP. (2007). Clinical aspects of the ketogenic diet. Epilepsia. 48(1): 31-42. https://www.ncbi.nlm.nih.gov/pubmed/17241206 Thus, it is important to discuss with your primary care physician to see if ketogenic diets are for you.
Another issue to consider when you go on a ketogenic diet is the quality of your food. This diet restricts your food choices, dictating that you eat more protein and fewer fruits and vegetables. This can significantly increase grocery bills. To compensate, some people buy low-quality processed proteins (such as canned meats or ready-made chicken nuggets) instead of high-quality fresh proteins (such as fresh chicken or steak), which can negatively affect health long-term. Because of the heavy dietary restrictions and cost, many people find long-term adherence to ketogenic diets difficult.
Will a ketogenic diet help me lose weight?
While people frequently report losing weight while on a ketogenic diet, the evidence supporting the diet’s benefits isn’t totally clear yet. For example, recent reviews show this diet has a minimal effect, though ongoing clinical trials on obese patients show a strong correlation with health improvement.6Churuangsuk C, Kherouf M, Combet E, Lean M. (2018). Low-carbohydrate diets for overweight and obesity: a systematic review of the systematic reviews. Obes Rev. 19(2): 1700-1718. https://www.ncbi.nlm.nih.gov/pubmed/301946962Ministrini S, Calzini L, Nulli ME, et al. (2019). Lysosomal acid lipase as a molecular target of the very low carbohydrate ketogenic diet on morbidly obese patients: the potential effects on liver steatosis and cardiovascular risk factors. J Clin Med. 8(5). https://www.ncbi.nlm.nih.gov/pubmed/31067824
As a biomedical researcher studying adipocyte mechanism—how fat is metabolized—I think that restricting calorie intake is more important for sustainable weight loss than following a specific dietary regimen. In general, it is best to find what dietary regimen is most enjoyable and sustainable for you, so that you can maintain the health benefits over a long period of time.
If you want more details, I suggest the following reviews:
- Do ketogenic diets really suppress appetite? A systemic review and meta-analysis. https://www.ncbi.nlm.nih.gov/pubmed/25402637
- Effects of ketogenic diets on cardiovascular risk factors: evidence from animal and human studies https://www.ncbi.nlm.nih.gov/pubmed/28534852
- The ketogenic diet: one decade later. https://www.ncbi.nlm.nih.gov/pubmed/17332207
- Beyond weight loss: a review of the therapeutic uses of very-low-carbohydrate (ketogenic) diets https://www.ncbi.nlm.nih.gov/pubmed/23801097