Thinking of trying a ketogenic diet and want to know what you’d be getting into? This article will give you the pros and cons and show you how to safely adjust your body to ketosis so you achieve the many benefits this lifestyle has to offer.
The ketogenic diet was first designed as a therapeutic diet to treat epilepsy that mimicked the benefits of severe calorie restriction without the drawbacks of literal starvation. Based on the fact that fasting relieved epileptic symptoms by forcing the body to produce ATP (the energy source for the body) from fat instead of glucose, a doctor at the Mayo clinic designed the ketogenic diet to have a similar effect.
Original recommendations for a ketogenic diet were to radically reduce carbohydrates to less than 20 grams per day, while providing a moderate protein intake of 1 g/kg/bw with the rest of the calories coming from fat. This makes fat the primary fuel source, with protein providing just enough amino acid building blocks to sustain lean tissue and produce other compounds in the body, including transmitters and enzymes.
In the last 15 years, the ketogenic diet has been modernized to allow for higher carb intakes (around 50 grams a day). It has gained in popularity, with a wealth of research showing many benefits, which we’ll get into below.
How Ketosis Works
In order to truly appreciate the “pros” and troubleshoot the “cons” it’s important to understand how a ketogenic diet works, so let’s cover that first.
On conventional high-carb diets, the body gets its energy from a steady supply of glucose in the blood (carbs are digested into glucose, which acts as the fuel source for ATP energy production).
By restricting carbohydrates on ketogenic diets, blood glucose levels fall. This leads a fat-burning enzyme called hormone sensitive lipase (HSL) to increase, releasing stored triglycerides (fat) from fat cells. Triglycerides are broken down into fatty acids and glycerol. The fatty acids travel to the liver, which turns them into ketones that can be used for energy in cells to produce ATP.
The Adaptation Process
One drawback to ketogenic diets is they require an adapatation process. If you’ve been living on a high-carb diet, your body won’t have the necessary enzymes to effectively burn fat. In this environment, ketones will be at a level of less than 0.3 millimolar (mM).
In the initial stages of carbohydrate restriction, the body won’t burn the ketones that are produced by the liver. Instead, they will be excreted in the urine and via respiration (breathing out). During this stage, the body relies on glucose from glycerol and liver glycogen for energy.
Soon enough, ketone levels will rise above 0.5 mM and the body will begin to use those ketones in the Krebs Cycle to produce ATP. When ketones are at a level between 0.5 and 5 mM, you’re in a range called “nutritional ketosis.” This state is when the body has reached keto-adaptation and will utilize ketones and fatty acids as the primary fuel source.
People often confuse nutritional ketosis with ketoacidosis, which is a dangerous condition. They are not the same thing. Ketoacidosis is an unstable condition that occurs when there is inadequate pancreateinc insulin response to regulate ketone levels in the blood. This occurs only in type I diabetes and late stage type II diabetes with advanced pancreatic burnout. In this setting of deficient insulin, blood ketone levels reach the 15 to 25 mM range, which is 5 to 10-fold higher than the levels characteristic of nutritional ketosis.
What About Brain Fuel?
Chances are you’ve heard the argument against low-carb diets that the brain needs glucose for energy. It’s true that the brain does need about 50 grams of glucose a day, but this doesn’t need to come from eating carbohydrates.
Rather, the body is capable of producing glucose from amino acids (from protein), glycerol (from dietary fat or fat tissue in your body)), and lactate and pyruvate, (produced from glycolysis). These substrates go to the liver where it turns them into glucose via the process known as gluconeogenesis.
The rest of the energy that the brain requires is derived from ketones. Having the brain get the majority of its energy from ketones actually improves brain function and is the reason that ketogenic diets are used to treat brain disorders.
The one “catch” to this system is that just as it takes time for the body to become adapted to ketosis, the brain has to go through the same process. During the adaptation period, brain function may suffer and feelings of fatigue may increase. But if you hang in there and stick it out, things should turn out nicely for you on all fronts!
Pros of Ketogenic Diets
Here is a snapshot of the benefits you can expect to achieve from a ketogenic diet:
Reduce insulin levels
Decrease insulin resistance
Reduce fat storage/increases fat burning
Increase thermogenesis—the amount of calories you burn daily
Spare muscle for better body composition
Lowers cancer risk
Decreases neurological disease
Greater endurance performance
Easier time losing fat for weight class/aesthetic sports
Best of all, ketogenic diets are a powerful treatment for obesity and can rapidly promote fat loss, while preserving muscle mass so that improvements in body composition are more sustainable. In one review of 13 randomized trials testing the effects of very low carb diets, ketogenic diets produced significantly greater weight loss than low-fat diets (about 1 kg greater). There were also greater improvements in metabolic markers like reductions in triglycerides, LDL, and blood pressure (1).
These results match up pretty well with individual randomized trials: For example, one study that compared a ketogenic diet (4% of calories from carbs) with a moderate-carb diet (35% calories from carbs) found that the ketogenic diet group lost a kilo more body fat and about 0.75 kg more total body water for a 2 kg greater loss in body weight (2).
A third trial looked specifically at the effect of a ketogenic diet in athletes (3). The study used gymnasts from the Italian national team and had them eat a ketogenic diet for one month in which they ate 55 percent fat, 40 percent protein and 5 percent carbs (carbs totaled no more than 28 grams, strictly from green vegetable sources).
The study included a “control” portion that was conducted three months after the low-carb diet in which the gymnasts ate their regular diet for a month (composed of 46 percent carb, 39 percent fat, and 15 percent protein) and then performed the same body composition and strength tests.
Results showed that on the ketogenic diet, the gymnasts lost an average of 2 kg of fat and dropped 2.6 percent body fat, while maintaining lean mass. Overall, they lost 1.6 kg of body weight, which noteworthy since gymnasts want to be as light as possible. When they returned to the regular diet that was higher in carbs, they gained back 1.5 kg of fat, ending with 7.7 percent body fat.
Just as important, the gymnasts did a series of strength and power tests and performed equally well before and after both the low-carb and normal carb diets.
Cons of Ketogenic Diets
Although ketogenic diets may seem like a godsend to anyone who has struggled for a lifetime to lose body fat or has had their quality of life plummet due to metabolic or cardiovascular disease, there are some drawbacks:
Athletes in sports with a high anaerobic energy component, such as basketball players, mixed martial artists, or soccer aren’t going to have the high rate of energy production necessary for maximal performance from running their bodies on ketones. The maximum rate of ATP resynthesis from ketones is only about 0.40 moL/min, whereas aerobic or anaerobic breakdown of glycogen can resynthesize ATP at a rate of 1.0 to 2.0 moL/min.
#1: The general ratios for a ketogenic diet are 75 percent fat, 20 percent protein, and 5 percent carbohydrates. However, these can be modified based on individual needs and goals. For the initial adaptation phase, carbs need to be below 50 grams a day, preferably from low-glycemic vegetables and selsct fruits, such as berries, or other low-carb fruit.
#2: Increasing the protein intake to as high as 30 percent of the diet may be useful for athletes. Ancestral humans ate about 30 percent protein daily, which corresponds to about 3g/kg/bw a day, indicating that a ketogenic can be safe if done properly.
#3: Don’t be afraid of the fat! At this point it should be obvious that dietary fat can be perfectly healthy and play a primary role in a diet geared at fat loss, but in light of the history of fat phobia, it may be worth mentioning. Just be sure to eat fat from a variety of sources (butter, coconut oil, olive oil, avocados, nuts, fish, and seeds).
#4: It’s recommended to get extra sodium and potassium to maintain nitrogen balance and preserve lean tissue. Get between 2.5 and 5 grams of sodium (1 to 2 teaspoons of table salt) and extra potassium from green veggies and other plants. Cooking with meat broths can help if you are sweating a lot during exercise.
#5: Supplemental fiber and protein can be used to drive protein intake up. Added fiber is necessary because a low-carb diet will be extremely low in fiber.
#6: Exericse may accelerate the keto adaptation process by helping to get the body into fat burning mode. Both aerobic exercise (ranging from 55 to 75 percent of maximal) and interval training has been shown to increase the use of fat for fuel and improve metabolic flexibility.
#7: Ensure hydration because the body naturally reduces its water stores when carbs are restricted. Shoot for 0.6 to 0.7 ounces per pound of body weight daily.
#8: Caffeine can be a useful aid when transitioning to a ketogenic diet. Drinking 1 to 3 cups of coffee can significantly enhance exercise performance and motivation when training with low glycogen stores.
#9: Get enough magnesium. When you restrict carbs and train hard, magnesium can become depleted due to its role in insulin metabolism. Supplementing with up to 500 mg day may be beneficial.
#10: Stay the course. Scientists write that it takes seven days for full metabolic adjustment to a low-carb ketogenic diet. Just because you don’t feel “right” during the first week doesn’t mean it won’t be effective.