If you haven’t been living under a rock for the past 5 years you’ve likely been exposed to the ketogenic diet in some way. Between the bulletproof coffee craze, MCT oil supplements, and celebrity endorsements this diet is at the tops of the charts as far as popularity goes. But how does it stack up for health?
The goal of the ketogenic diet is to purposefully push the body into the metabolic state of ketosis. Under normal physiologic conditions glucose (from broken down carbohydrates) serves as our primary energy source. The brain and red blood cells have a particularly high preference for glucose fuel. Ketosis results when we do not consume adequate carbohydrates and our stored carbohydrates (glycogen) have been used. Since we still require energy, the body responds by switching its fuel source to ketones. Ketones are made from fatty acids, therefore, ketosis can be thought of as a fat burning metabolic state. Historically speaking ketosis has been seen in periods of famine and starvation or during prolonged exercise periods. However, we can also induce ketosis by strictly limiting carbohydrates in the diet.
There are various ketogenic diet types and these variations differ in the total carbohydrate intake allowed. It is important to note that a true ketogenic diet is not simply a low carbohydrate diet, it requires restricting carbohydrates enough to push the body into ketosis. Specific carbohydrate intake requirements will depend on the individual but generally ketosis is met by limiting carbohydrates to around 20 grams per day. In fact, ketogenic diets recommend that you avoid all grains and starches, as well as most fruits, legumes, and many dairy products. Instead, it is suggested that you reach your limited carbohydrate goal through consumption of low carbohydrate vegetables, nuts, seeds, and low-sugar berries. The point here being that the ketogenic diet is extremely restrictive. The diet instead suggests that the majority of total calories come from fat. Foods like beef (steak & ground), pork (loin, sausage, bacon), lamb, skin-on poultry, organ meats, fish and shellfish, eggs, and cheeses are consumed freely and fats like oils, butter, and lard are encouraged.
There are many disadvantages to the ketogenic. In fact, on the U.S News & World Report’s ranking of 40 popular diets, the ketogenic diet was tied for last place. Diets were ranked based on scores in categories including compliance, short and long-term weight loss, nutritional quality, and effectiveness against disease. An expert panel comprised of the country’s top dietitians, dietary consultants, and physicians specializing in diabetes, heart disease, and weight loss performed the scoring for the ranking. Attributes of the diet that helped it to earn the last place ranking include nutritional quality, compliance, effectiveness against disease, and long-term weight loss.
The nutritional quality of the ketogenic diet was described as “extremely incomplete.” Because multiple food groups are being (almost) eliminated in this diet, dieters will have to be well educated and plan accordingly in order to meet all their micronutrient and fiber needs. Although it may be possible to meet these needs via the ketogenic diet it should be noted that certain foods avoided on the diet (such as whole grains, legumes, and fruits) are staples in evidence based healthy diet recommendations and in eating patterns in world regions experiencing the lowest disease rates. It is one thing to restrict added sugar and refined grains (and maybe to limit overall carbohydrate intake) but it is another story to avoid healthy sources of carbohydrates all together. It is by no means a requirement that you eliminate these foods to support health.
Attention should be given, not only to the insufficiencies in nutrient content in this diet, but also to the nutrient that is abundant: saturated fat. It has been a recommendation for decades to limit saturated fat intake, this recommendation is based on research that suggested that high intake of saturated fat adversely impacts risk factors for cardiovascular disease. While a more recent study indicated that saturated fat intake actually is not correlated with increased disease risk, most experts agree that this study is not enough to disregard other abundant findings. Recommendations for limiting saturated fat are further supported by the fact that populations experiencing the lowest disease rates and longest lives consume diets limited in this fat type.
Another criticism of the ketogenic diet is the large consumption of red and processed meats. Diets high in these food types have continuously been associated with increased colon cancer risk. One expert from the diet-ranking panel noted “any diet that recommends snacking on bacon can’t be taken seriously as a health promoting way to live.” Although we may all wish it could!
The exceptionally restrictive nature of the ketogenic diet is another major disadvantage. Dieters find it difficult to adhere to this diet and often relapse to normal eating patterns fairly quickly. Even if a diet has great results, if it is unsustainable the results are also unsustainable. Most research on the ketogenic diet has been short-term, meaning that reliable studies researching long-term effects of the ketogenic diet are non-existent. This may be partially due to the difficulty remaining on the diet.
Of course, the ketogenic diet did not become so popular having no benefits at all. In fact, on that same diet ranking report where ketogenic came in last place overall, it scored exceptionally high in one specific category. In many studies short-term weight loss is seen on the ketogenic diet. The reason for this is multifactorial. Firstly, ketosis initiation results in total glycogen depletion. As noted above, glycogen is our body’s stored form of glucose. Glycogen is stored in muscle and liver tissues with water. As such, when you deplete your glycogen stores in the early days of the ketogenic diet you will experience water weight loss. When the body enters ketosis and switches to a fat burning state continued weight loss occurs. Anecdotal reports describe a weight loss plateau after initial loses. Also remember that any diet that is not sustainable has un-lasting results.
There are some specific populations who may benefit from following a well-structured ketogenic diet. The diet has been shown to be an exceptionally effective way to halt medication resistant epileptic seizures in children. Growing research also indicates that the ketogenic diet may be appropriate in decreasing cancer cell survival by starving the cells of glucose. It is important to note, however, that antioxidant and fiber rich foods that have been shown time and time again to stave off cancer development in the first place are eliminated and restricted on the ketogenic diet.
The ketogenic diet is extremely effective for short-term weight loss and has become increasingly popular in recent years. While the diet has shown to be effective in treating some very specific disease states, it is not in alignment with most healthy eating and disease preventing diet types. If choosing to follow the ketogenic diet, it is important to become familiar with healthy, unsaturated fats and fiber intake strategies to reduce chances of adverse health outcomes on this extremely restrictive diet.