Every few seasons a fad diet gets its chance in the spotlight. This season, the ketogenic or “keto” diet is taking center stage. A ketogenic diet (KD) is very low in carbohydrate, moderate in protein, and high in fat. Originally developed to treat epilepsy in children, researchers are now exploring the KD in cancer, obesity, type 2 diabetes, Alzheimer’s disease, inflammation, and movement and neurological disorders treatment. The KD for weight loss is stirring up conversation in the nutrition community. Before deciding if this diet is for you, it is important to explore both sides of the issue.
The ketogenic diet is characterized by a reduction in carbohydrate and an increase in protein and fat. By drastically decreasing carbohydrate intake and increasing fat and protein consumption, the body goes into a state called ketosis. Normally, carbohydrates are the body’s preferred source of energy. However, when carbohydrates are not available, other sources must be used for energy. Simply put, during the process of ketosis the body breaks down fat, turns it into ketones, and uses those ketones for energy. In other words, the body uses fat as its main energy source.
There is no standard ketogenic diet, and the amount of carbohydrate, protein, and fat consumed while following this diet can vary. On average, the recommended carbohydrate intake for someone on the keto diet is approximately 20-30 grams per day. This would equate to the amount of carbohydrate in a small to medium sized apple. The Modified Atkins Diet is a type of KD that limits carbohydrate to 20 grams per day but does not restrict protein, fat, or total calories. Because the ketogenic diet is a high fat diet, the majority of an individual’s calories come from fats. In fact, fat makes up about 70% of the daily caloric intake, while protein makes up about 25%. Typical foods a person following a KD eat are fish, poultry, other meats, whole eggs, most types of cheese, and moderate amounts of nuts, butter, margarine, cream, mayonnaise and oils. Limited foods include fruits, starchy type vegetables, grains, and high-sugar peppers, onions, tomatoes and sugar.
The drastic differences between the ketogenic diet and a normal, healthy eating plan has led to questions about the diet’s safety and long-term effectiveness for weight loss. Research has shown some evidence of effectiveness in short-term weight loss in individuals following a keto diet. In a 4-month study comparing a KD to a low-fat diet, the KD group lost 6% more body weight on average than the low-fat diet group. Another study over a 6-month period determined that weight loss was greater in subjects on a KD versus those on a standard, low-calorie diet. Additionally, these studies reported improvements in blood sugar, cholesterol, and triglyceride levels in participants following a KD. Nonetheless, adverse effects such as constipation, headache, muscle cramps, and fatigue were more common in those following a KD. It is important to note that despite these studies, the long-term effectiveness of the KD has not been well researched. The ability to maintain weight loss and the occurrence of side effects past one year is unknown.
It is important to recognize the differences between the ketogenic diet and the Dietary Guidelines for Americans. The 2015-2020 Dietary Guidelines for Americans recommend consuming a healthy eating pattern that accounts for all foods and beverages within an appropriate calorie level. The guidelines identify a healthy eating pattern to include a variety of vegetables, fruits, especially whole fruits and grains, at least half of which are whole grains. These are food groups that are restricted with the keto diet. In addition, the dietary guidelines recommend consumption of heart healthy, unsaturated fats, such as oils, and a reduction of saturated fat found in meat and high fat dairy foods to less than 10% of total calories per day. A diet too high in saturated fat increases the risk for heart disease.
Before starting any diet, it is essential to assess its safety and potential impact on your health. The ketogenic diet is not recommended for people with kidney problems, liver disease, gastroesophageal reflux (GERD), heart concerns, or chronic constipation. People with diabetes should talk to their doctor to make sure this diet does not interfere with their medications or other health complications. In any case, do not begin any new diet without first talking to your doctor or registered dietitian to see if it is appropriate for you.