By: Zachari Breeding, MS, RDN, CSO, LDN, FAND

What is the Ketogenic Diet?

The Ketogenic Diet was initially developed and used to treat children suffering from epileptic seizures, with emerging research indicating the efficacy in those with glioblastomas (a type of brain cancer). It is essentially a high-fat, moderate-protein, and very low-carbohydrate approach. Eating so few carbohydrates (typically under 50g per day) forces the body to use fat from the diet (rather than carbohydrates) as the body’s main source of fuel. Instead of glucose, which is derived from the carbohydrates we eat, the body relies on energy from ketone bodies derived from fat. After following this regimen for several days to a week, the body will be in what is called ketosis.

It is common to hear different definitions and criteria for what is considered “keto”. While there is no standard or strict criteria on what portion of calories from fat, carbs, and protein comprises the ketogenic diet, it is clear what isn’t keto. The ketogenic diet is not a “high-protein” diet. Whereas some other low-carb diets (such as the modified-Atkins diet) emphasize that as much as 30% of daily calories should come from protein, the protein content in many ketogenic diets is dialed back to around 10%. This leads to a very important claim of the diet; if protein intake is too high, the body has enough of the amino acids glutamine and alanine to convert into glucose, which can knock a person out of ketosis. However, the research on this claim is not well supported. Ketosis is a continuum, with an increasing number of ketones as with greater carbohydrate restriction.

The ketogenic diet is a high fat diet. Carbohydrate intake must be low enough to allow the body to use ketones as fuel, and protein must be moderate but not too high in order to not disrupt ketosis. The most commonly used ketogenic ratio is 4:1, which describes a diet that is made of 4 grams of fat for every 1 gram of protein or carbohydrate. In other words, for every 5 grams of food consumed, there are 4 grams of fat and 1 gram of protein and/or carbohydrate. Someone who is aiming to adhere to the 4:1 ratio will have to use a gram scale for accuracy. A real-life example of this would be 1 gram of kalamata olives, which have 0.07g carbs, 0g protein, and .28g fat.

Why Is the Ketogenic Diet so popular?

The ketogenic diet has seen a huge surge in popularity in recent years. Supporters of this approach state the high fat intake keeps you full and satisfied, and that the diet boosts energy levels and reduces or eliminates cravings. Opponents of this diet argue that the popularity of this diet comes from historical popularity of Paleo, Atkins, and other carbohydrate-restricting meal patterns. Many people struggle to limit portions with indulgent foods that contain carbohydrates and sugar, such as cookies, cake, doughnuts and potato chips. The ketogenic diet nearly eliminates carbohydrates, including fruit and starchy vegetables. Restricting the diet in this way, especially when paired with physical activity, can result in accelerated weight loss. It should be noted that we have yet to see long-term data to suggest sustained weight loss while following a long-term ketogenic diet.

Should I consider the Ketogenic Diet?

We know there is short-term weight loss benefit, at the very least. Emerging data is unveiling a potential benefit in diabetes. Some data suggest a potential benefit in glioblastomas. There may be nothing wrong with short-term adherence to a ketogenic diet followed by weight maintenance with sustained physical activity. And while the ketogenic diet may seem enticing based on the proposed benefits, there are still some red flags to consider.

The primary consideration is the basic logic of why the ketogenic diet is useful in those with epilepsy: it deprives the brain of its preferred source of energy. For optimal functionality, a person should consume, on average, at least 120-130g of carbohydrate daily to support brain and eye health. With keto, we find that limiting the brain’s preferred energy also limits activity from the neurotransmitters (i.e. GABA) that cause seizures. If you deal with epilepsy, a personalized ketogenic diet with the guidance of an experienced registered dietitian may be appropriate.

Of note were two interesting studies conducted about keto. One study looked at data from about 400,000 people and concluded that those who ate high carb diets (over 70% of their calories from carbs, 45-65% is recommended) AND low-carb diets (under 40% of their calories from carbs) resulted in the SAME high risk of mortality. However, substituting a reduced carb diet with plant-based protein sources resulted in reduced risk of death. Interestingly, this was not the case for those who substituted their low-carb diets with animal-based protein. The other study reviewed data from about 25,000 people who participated in the NHANES (U.S. National Health and Nutrition Examination Survey). The data showed that those following a low-carb diet (under 40% of their calories from carbs) were 51 percent more likely to die from heart disease, 50 percent more likely to die from cerebrovascular disease and 35 percent more likely to die from cancer. The study concluded stating a diet in which 50%-55% of total energy came from carbohydrates was associated with the least risk of death compared to the other groups.

What else should I consider?

The ketogenic diet doesn’t just eliminate a food group, unlike the Paleo diet, for example, which excludes grains and legumes. It almost completely eliminates a nutrient: carbohydrates. This exposes a person to nutrient deficiencies if they don’t plan their food choices well, specifically the B vitamins, calcium, potassium, and vitamin K. Developing nutrient deficiencies can create serious health problems, including anemia, osteopenia and osteoporosis, joint pain, and inhibited immune system function. Someone who is not good at planning their meals ahead should not consider this type of diet.

Remember that fad diets come and go. Right now, keto is hot. Eventually another diet trend will come along and steal the attention of the public. Though there may be some real clinical benefit to the ketogenic diet, the tried-and-true recommendation of a balanced diet inclusive of all food groups has continued to be the consistent message. When deciding if the keto diet is for you, consider long term as well as short term health goals. Registered dietitians are key resources in guiding people along the path to wellness.

References

1. Abbasi, J. (2018). Interest in the Ketogenic Diet Grows for Weight Loss and Type 2 Diabetes. JAMA,319(3), 215. doi:10.1001/jama.2017.20639
2. Dulloo, A. G., & Montani, J. (2015). Pathways from dieting to weight regain, to obesity and to the metabolic syndrome: An overview. Obesity Reviews,16, 1-6. doi:10.1111/obr.12250
3. Gibson, A. A., Seimon, R. V., Lee, C. M., Ayre, J., Franklin, J., Markovic, T. P., . . . Sainsbury, A. (2014). Do ketogenic diets really suppress appetite? A systematic review and meta-analysis. Obesity Reviews,16(1), 64-76. doi:10.1111/obr.12230
4. Johnston, C. S., Tjonn, S. L., Swan, P. D., White, A., Hutchins, H., & Sears, B. (2006). Ketogenic low-carbohydrate diets have no metabolic advantage over nonketogenic low-carbohydrate diets. The American Journal of Clinical Nutrition,83(5), 1055-1061. doi:10.1093/ajcn/83.5.1055

5. Figure 1. J Physiol. 2017 May 1; 595(9): 2857–2871. Published online 2016 Dec 7. doi: 1113/JP273185. Accessed August 22, 2019: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5407977/figure/tjp12106-fig-0001/.

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