There is a big movement in the industry right now toward ketogenic diets and diets that claim to be ketogenic when, in reality, they are just low carb. Keto diets are very popular, so we will talk about it all -- the good, the bad, and the ugly. In this article we will discuss why I believe that ketogenic diets or low carb diets are not the answer, where ketones and ketogenic diets can be useful, and why you still need to be eating carbs. Let’s start with some definitions.
First, we have to understand what ketosis actually is. Ketosis is defined by Medline Plus as “an abnormal increase of ketone bodies in the body in conditions of reduced or disturbed carbohydrate metabolism.”
Ketosis happens when there is a lack of glucose present in the blood stream, a lack of insulin to use that glucose, or in times of starvation. Glucose is just broken down carbohydrate. Any carb you eat from oatmeal to gatorade is broken down into glucose and utilized as energy or stored as glycogen or fat. Glucose is also the prefered energy source for your brain! Without glucose your body has to create an alternative fuel source for your body so your brain can work. Ketosis is actually a starvation survival strategy built into the body, so when there is no food present the body will not break down muscle to get glucose to fuel the body. When there is a lack of glucose in the body insulin is down regulated. This down regulation of insulin causes this process to take effect. When this happens, the body has to switch over from using glucose as its source of energy to ketone bodies, which are created from the breakdown of fat and protein.
Along with glucose being your brain's preferred energy source glucose is also provides a valuable function in energy production. Your anaerobic systems or “fast energy systems”, what you would use to sprint, throw, jump or lift weights for short periods of time, are glucose dependent, where the aerobic system or “slow energy system”, used predominantly at rest, or during long duration low intensity exercise is not glucose dependent. This will be important in a minute.
But breaking down fat is a good thing right?
Just because fat is used to create the ketones does not mean that you are burning more body fat when you go into a state of ketosis, you are just using fat to make ketones for energy as opposed to breaking fat down to directly create energy. Even though ketosis is a starvation survival strategy you can still gain body fat while on a ketogenic diet. Fat gain occurs when there is excess energy present. More calories than the body needs in any form -- carbohydrate, fat or protein -- will cause body fat gain. Fat oxidation is the primary way that we utilize stored energy at rest and during long duration exercise, your “slow energy system” mentioned above. So fat breakdown is happening at rest either way, ketosis or not.
To reach a state of ketosis your diet has to be pretty specific or you have to be starving for a day or two. One thing we have to keep in mind is that your body can turn protein into glucose, so if you are eating a relatively high protein diet you are not in a state of ketosis. An actual ketogenic diet is over 70% fat and under 5% carbohydrate. That leaves you with about 20-25% of your diet from protein, so if you are eating a high protein diet and think you are in ketosis you are wrong. The only way to really know if you are in ketosis is if you pee on a ketone test strip and have ketones in your urine or you can get a blood test.
Ketosis can cause sickly sweet breath, a loss of appetite, a decrease in performance, and brain fog. As we talked about earlier, your brain and body’s main preferred energy source is glucose, so you will not be able to think clearly or perform well during your workouts when you first enter ketosis and it can take as long as a month until you fully switch over to ketosis. There are also concerns for the athlete because fast energy systems in the body are dependent on glucose; if you are on a ketogenic diet you will not perform to your full potential in most team sports that are dependent on quick burst of energy.
Ok so now that we have all that out of the way, let's talk about how ketosis can be beneficial to the body. There are some cases in which following a strict ketogenic diet can be beneficial for health. Science says that ketogenic diets can reduce the frequency of seizures, help slow the process of alzheimer's, and reduce the growth of cancer cells. There is a great video by Layne Norton PhD explaining this here and a research review here.
People have also reported extreme weight loss on keto diets and that is the real point of this article. There is nothing special about the ketogenic diet and how it makes you lose weight. In fact, the scientific evidence shows that if two diets contain the same amount of calories, one being ketogenic and the other a normal diet (containing carbs, proteins, and fats at relatively equal levels), there is no difference in fat loss. (Study Link) This comes down to an even bigger point. If any diet creates a caloric deficit you will lose weight. Any distribution of food, any ratio of carbohydrates, proteins, and fats and you will lose weight. However, there is evidence to show that a high protein diet will help with fat loss if calories are the same. This is because it takes more calories to break down protein than the other two macronutrients, in addition to the fact that protein keeps you fuller longer compared to other foods which will in turn help you… you guessed, it eat less calories! Which is the basis of all successful fat loss diets. More talk about the studies supporting this notion here from Examine.com
Keto and Sustainability
As much as keto might help you lose weight, there is a big issue with using it for this purpose. It is not sustainable! In keto, you basically have to eat high fat meats and oils for every meal ever! If you can’t keep your calories low enough without cutting out carbs all together, then as soon as you add them back in the likelihood of overeating and gaining weight is high.
Another issue with keto is that when you drop your carbs, you deplete something called glycogen, which is carbohydrate stored in your liver and muscles fiber. This accounts for about 1,500-2,000 calories of energy or 400-500g of carbs. What most people don’t realize is that every gram of glycogen holds about 2.7g of water, meaning that when you deplete your body of glycogen like in a keto diet, you will lose that water weight. That being said, as soon as you add carbohydrates back into you diet, you will replenish that glycogen and regain the water and glycogen that was lost. So when you initially lose weight on an extremely low carbohydrate diet, you are losing mostly water weight not fat weight; the fat weight loss comes after sustaining a lower calorie diet consistently over time.
If you are ok with never eating a carbohydrate again in your life, then be my guest and get on a keto diet. You can slowly work your way back to eating carbs, but it is hard. My suggestion is to eat a calorie controlled, high protein, moderate carbohydrate, moderate fat diet and track your calories daily. This is the most sustainable, most effective way to reach your fat loss and fitness goals.
In part 2 we will go in depth on why carbohydrates are super important for the team sports athlete.