Low-carbohydrate diets have gained significant attention for their potential health benefits, particularly in the realms of weight loss, blood sugar control, and even certain neurological conditions. At the heart of these diets lies the concept of manipulating macronutrient ratios to shift the body's primary fuel source from carbohydrates to fats. Among the various low-carb approaches, the ketogenic diet stands out due to its strict macronutrient guidelines and its ability to induce a metabolic state known as ketosis.
Understanding the Ketogenic Diet
The ketogenic diet, often referred to as "keto," is a high-fat, moderate-protein, and very low-carbohydrate eating plan. In a typical modern diet, the majority of calories come from carbohydrates, with moderate protein intake and a little bit of dietary fat. The keto diet flips this ratio, drastically reducing carbohydrate intake to less than 50 grams per day, and sometimes as low as 20 grams. This reduction forces the body to seek alternative fuel sources, primarily fat.
Ketosis: The Metabolic Shift
When carbohydrate intake is severely restricted, the body's glucose reserves become depleted. Glucose serves as the human brain’s primary source of energy, as fatty acids are unable to pass the blood-brain barrier. In response, insulin levels drop, and the liver begins to break down stored fat into ketone bodies. These ketone bodies, including acetoacetate, beta-hydroxybutyrate, and acetone, can be used by the brain and other tissues as an alternative fuel source. When ketone bodies accumulate in the blood, this state is called ketosis. Achieving and maintaining ketosis is the primary goal of the ketogenic diet.
Healthy individuals naturally experience mild ketosis during periods of fasting (e.g., sleeping overnight) and very strenuous exercise. Proponents of the ketogenic diet state that if the diet is carefully followed, blood levels of ketones should not reach a harmful level (known as “ketoacidosis”) as the brain will use ketones for fuel, and healthy individuals will typically produce enough insulin to prevent excessive ketones from forming. [2] How soon ketosis happens and the number of ketone bodies that accumulate in the blood is variable from person to person and depends on factors such as body fat percentage and resting metabolic rate.
Ketoacidosis: A Dangerous Imbalance
It's important to distinguish between ketosis and ketoacidosis. Excessive ketone bodies can produce a dangerously toxic level of acid in the blood, called ketoacidosis. During ketoacidosis, the kidneys begin to excrete ketone bodies along with body water in the urine, causing some fluid-related weight loss. Ketoacidosis most often occurs in individuals with type 1 diabetes because they do not produce insulin, a hormone that prevents the overproduction of ketones. However in a few rare cases, ketoacidosis has been reported to occur in nondiabetic individuals following a prolonged very low carbohydrate diet.
Read also: Walnut Keto Guide
Macronutrient Ratios: The Key to Ketosis
While there isn't one "standard" ketogenic diet, the general guidelines emphasize a specific ratio of macronutrients:
- Fat: 70-80% of total daily calories
- Protein: 10-20% of total daily calories
- Carbohydrates: 5-10% of total daily calories
For a 2000-calorie diet, this translates to approximately 165 grams of fat, 40 grams of carbohydrate, and 75 grams of protein.
Carbohydrate Limits: The Foundation of Keto
The cornerstone of the ketogenic diet is restricting carbohydrate intake. This typically means limiting total carbohydrate intake to less than 50 grams per day, and sometimes as low as 20 grams. To calculate your net carbs, subtract fiber, sugar alcohols, and other nondigestible carbs from the total amount. These are the carbs to watch on a ketogenic diet. This forces the body to rely on fat for fuel and enter ketosis.
Foods to Avoid: Many versions of ketogenic diets exist, but all ban carb-rich foods. Some of these foods may be obvious: starches from both refined and whole grains like breads, cereals, pasta, rice, and cookies; potatoes, corn, and other starchy vegetables; and fruit juices. Some that may not be so obvious are beans, legumes, and most fruits.
Low-Carb Alternatives: You can follow the keto diet by establishing a daily carb limit. Eat keto by restricting foods with high net carbs and fueling up on healthy fats and protein. Vegetables contain fewer carbs, lower calories, and higher fiber than fruits. They are packed with phytonutrients, vitamins, and minerals, and are an important part of any healthy diet. Low-carb fruits should be a part of the ketogenic lifestyle. Examples of low-carb fruits are raspberries, blackberries, strawberries, watermelon, cantaloupe, kiwi, peaches, clementines, and grapefruit.
Read also: Wine on a Keto Diet
Protein Intake: Moderation is Key
While the ketogenic diet is high in fat, it's also important to consume a moderate amount of protein. The protein amount on the ketogenic diet is kept moderate in comparison with other low-carb high-protein diets, because eating too much protein can prevent ketosis. When the body doesn’t have sufficient carbs, amino acids from proteins you eat will be turned into glucose via a process called gluconeogenesis. This can become a problem on very low carb ketogenic diets and prevent your body from going into full ketosis. A good range to aim for is 0.7-0.9 grams of protein per pound (1.5-2.0 grams per kg) of body weight.
Fat Consumption: Fueling Ketosis
On the ketogenic diet, healthy fats are your best friends. Fat intake around 70% of total calories may be a good choice for some people on low carb or ketogenic diets. To get fat into this range, you must choose fatty cuts of meat and liberally add healthy fats to your meals. Strong emphasis on fats at each meal and snack to meet the high-fat requirement. Most ketogenic plans allow foods high in saturated fat, such as fatty cuts of meat, processed meats, lard, and butter, as well as sources of unsaturated fats, such as nuts, seeds, avocados, plant oils, and oily fish.
Medium Chain Triglycerides (or MCTs) are a form of saturated fat that is able to skip primary digestion and go straight to the liver, where they break down into ketone bodies.
Variations of the Ketogenic Diet
While the standard ketogenic diet (SKD) is the most common approach, several variations exist to cater to different needs and lifestyles:
- The Standard Ketogenic Diet (SKD): The standard ketogenic diet is the form of the diet that most dieters are familiar with. It’s very low-carb, moderate-protein, and high in fat. Your macros stay the same every day. When following the SKD you should aim for no more than 5-10% of your daily calories to come from carbs.
- The Cyclical Ketogenic Diet (CKD): The cyclical ketogenic diet is a variation on the diet that allows your total carbohydrate intake to vary by the day. The CKD allows for 2 non-consecutive days of higher-carb intake, usually for the sake of athletic performance. By allowing you more carbs (100-150g) the day before an intense workout, your liver is able to store up that glucose and use it to enhance your performance. Keep in mind that 100-150g is still considered low-carb.
- The Targeted Ketogenic Diet (TKD): The Targeted ketogenic diet (TKD) is very similar in concept to the cyclical ketogenic diet. The difference is that higher carbohydrate foods are saved for right before workouts, rather than planning an entire day of consuming more carbs. This approach to the ketogenic diet has also been useful for neurological conditions such as narcolepsy and dementia.
- The High-Protein Ketogenic Diet (HPKD): The high-protein ketogenic diet is much like the standard keto diet in that you still stick to just 5-10% of your daily calories coming from carbohydrates. But instead of 15-20% of your calories coming from protein, you aim for 30% protein instead, reducing your fat intake to 60-65%. The HPKD is still a high-fat, low-carb diet and will stabilize your blood sugar, increase your energy, and reduce your cravings. Ketosis is harder to get to and maintain.
Whatever version of the diet you pick, remember that you’ll likely adjust and find a sweet spot just for you that might not fit any of these templates perfectly. That’s just fine! Use the calculator/chart below or consult a healthcare professional.
Read also: The Keto-Brain Fog Link
Common Mistakes to Avoid
While low carb diets are very popular, it’s also easy to make mistakes on them. To reap all the metabolic benefits of low carb diets, merely cutting back on carbs isn’t enough.
- Skipping Fats: A very low carb diet must be high in fat. Otherwise, you won’t get enough energy or nutrition to sustain yourself.
- Eating Too Much Protein: Excessive protein consumption on a low carb diet can prevent you from getting into ketosis.
- Not Replenishing Sodium: Low carb diets lower your insulin levels, making your kidneys excrete excess sodium. This can lead to a mild sodium deficiency. The best way to avoid this issue is to add more sodium to your diet. You can do this by salting your foods - but if that doesn’t suffice, try drinking a cup of broth every day.
Potential Benefits and Risks
The ketogenic diet has been shown to produce beneficial metabolic changes in the short-term. Along with weight loss, health parameters associated with carrying excess weight have improved, such as insulin resistance, high blood pressure, and elevated cholesterol and triglycerides. [2,7] There is also growing interest in the use of low-carbohydrate diets, including the ketogenic diet, for type 2 diabetes.
Potential Benefits
- Weight Loss: Numerous studies show weight loss with keto without counting calories. Insulin levels drop and stored fat becomes the body's primary energy source.
- Improved Blood Sugar Control: Eating keto diets can significantly lower blood glucose and help reduce fat storage.
- Appetite Suppression: Participants reported less hunger and a reduced desire to eat compared with baseline measures. The authors noted the lack of increased hunger despite extreme restrictions of both diets, which they theorized were due to changes in appetite hormones such as ghrelin and leptin, ketone bodies, and increased fat and protein intakes.
- Potential Therapeutic Uses: This approach to the ketogenic diet has also been useful for neurological conditions such as narcolepsy and dementia.
Potential Risks and Side Effects
- The Keto Flu: The Keto flu is a collection of symptoms you may experience as your metabolism shifts into ketosis. Most of these symptoms subside in just a week or two, at which point you should start feeling the more positive effects of ketosis.
- Nutrient Deficiencies: Possible nutrient deficiencies may arise if a variety of recommended foods on the ketogenic diet are not included. It is important to not solely focus on eating high-fat foods, but to include a daily variety of the allowed meats, fish, vegetables, fruits, nuts, and seeds to ensure adequate intakes of fiber, B vitamins, and minerals (iron, magnesium, zinc)-nutrients typically found in foods like whole grains that are restricted from the diet.
- Long-Term Health Concerns: Some negative side effects of a long-term ketogenic diet have been suggested, including increased risk of kidney stones and osteoporosis, and increased blood levels of uric acid (a risk factor for gout).
Sustainability and Long-Term Adherence
Ketogenic diets have been demonstrated to be sustainable long-term for many patients who need them. For the average person using a ketogenic diet to lose weight, however, the extreme carb restrictions aren’t something they are prepared to sustain for life. Eating a lower amount of carbs per day may have metabolic benefits and support weight loss. But eating too much or not enough of certain nutrients like protein and fats can prevent your body from reaping the benefits.
Following a very high-fat diet may be challenging to maintain. Eliminating several food groups and the potential for unpleasant symptoms may make compliance difficult. An emphasis on foods high in saturated fat also counters recommendations from the Dietary Guidelines for Americans and the American Heart Association and may have adverse effects on blood LDL cholesterol.
Consulting Professionals
The exact ratio of fat, carbohydrate, and protein that is needed to achieve health benefits will vary among individuals due to their genetic makeup and body composition. Therefore, if one chooses to start a ketogenic diet, it is recommended to consult with one’s physician and a dietitian to closely monitor any biochemical changes after starting the regimen, and to create a meal plan that is tailored to one’s existing health conditions and to prevent nutritional deficiencies or other health complications.
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