Ketogenic or keto diets are all the rage these days. Originally developed as an adjunct treatment for epileptic children, keto emphasizes high-fat, moderate protein, and negligible carb intake, with the ultimate goal of placing the body into a state of ketosis. A great fuss has been made surrounding this “alternative” metabolic state, which has the body running on mainly fat instead of carbohydrates. You may have even heard some of the more attention-grabbing benefits of ketosis, too.
Today, we’re taking a deep-dive into all things ketosis — what it is, how it affects the body, and what benefits are associated with being in a state of ketosis.
Let’s start at the top.
What is Ketosis ?
Ketosis is a natural metabolic state in which your body runs primarily on fats and ketone bodies, instead of carbohydrates (i.e. glucose).
What are Ketone Bodies ?
Ketone bodies, or ketones for short, are a by-product of fat metabolism. You see, when you are in nutritional ketosis, there is not enough glucose available (the primary source of energy for cells) to meet demand and keep our bodies running as they should. To sustain life, the body turns to its “backup” fuel system — ketones.
Ketones are produced in the liver from the breakdown of adipose tissue (body fat) and dietary fats. Our cells can then burn these ketones for energy. The process of ketone generation, unsurprisingly, is called ketogenesis, and it’s going on all the time. However, the rate of ketone production and magnitude of your ketogenic state depends mostly on how much dietary carbohydrate (and protein) you have.
The more carbohydrates you consume, the less ketones you will produce. This is due to the fact that consuming carbohydrates (and protein) elevate insulin levels, which blunts fat breakdown. While your body is running on glucose, ketogenesis is shifted to standby, resulting in a very low blood ketone concentration (about 0.1 mmol/L).
Three Types of Ketones
There are three primary ketones the liver can produce from fats:
● Acetoacetate (AcAc) — second most abundant ketone, accounting for ~20% of total ketone blood concentrations.
● Beta-Hydroxybutyrate (BHB) — This is the most well-known and abundant ketone, accounting for ~78% of the total ketone concentration in the blood. BHB can also been found under the names: 3-hydroxybutyric acid and 3-hydroxybutanoic acid (3HB)
● Acetone — least abundant ketone, accounting for a paltry 2% of ketones in the blood.
Now, it’s important to note that our cells can use either BHB or Acetoacetate (AcAc) for energy production but does not use acetone.
Current estimates indicate that a keto-adapted adult can generate around 150+ grams of ketones per day following a complete fast, and between 50-100 grams per day on a properly constructed ketogenic diet.
However, during the initial transition to a ketogenic lifestyle, your body (for lack of a better term) “freaks out”, meaning it has difficulty transitioning into ketosis and producing enough ketones to keep energy levels, focus, and mood stable. This results in many individuals experiencing flu-like symptoms (i.e. “keto flu”) during the first few days (and even weeks) of adopting a ketogenic diet.
The reason the transition is rough for certain individuals (particularly those who have consumed WAY too many carbs as part of their diets) is that the body has gotten used to running on glucose for years and years.
Your body relies on a main energy source which is typically glucose. By depleting glucose, your body burns fat as the main source of energy with the production of ketones.
As such, its metabolic machinery is primed to process glucose for fuel, and it isn’t as optimized to burn fat and create ketones on a large scale. That is, unless you’ve experimented a fair amount with various fasting protocols (such as intermittent fasting) which require the body to rely on its fat stores more frequently and heavily since you’re going without food for considerable lengths of time.
What is a “Proper” Keto Diet?
The goal of a ketogenic diet is simple — to facilitate the transition and maintain a state of nutritional ketosis. Essentially, this is accomplished by starving the body of glucose and eating a lot of fat.
As such, a ketogenic diet is one that emphasizes dietary fat, provides modest amounts of protein, and allows for virtually no carbohydrates. In terms of “real world” numbers, the typical ketogenic diet contains the following macronutrient percentages:
● Fat: 75%
● Protein: 15-20%
● Carbohydrates: 5-10%
The amount of carbohydrates you’re allowed on a keto diet is primarily a function of your exercise regimen and energy expenditure. Basically, the more high-intensity type training you perform, the more carbohydrates you can “get away” with eating and still remain in a state of ketosis.
The reason for this is that high-intensity exercise (sprinting, resistance-training, etc.) is glycolytic in nature, meaning it’s powered by glycogen (glucose) primarily. Since you’re burning through more glucose when performing this type of training, you create a larger metabolic sink that can help “soak up” more glucose while still remaining in ketosis.
How to Reach Ketosis ?
Entering into ketosis sounds pretty straightforward — avoid carbohydrates and replace those carb calories with calories from dietary fat.
Typically, an individual will enter into a state of nutritional ketosis when their intake of dietary carbohydrates is <50 grams per day. In the absence of glucose, the body ramps up ketone production, and when blood ketone levels are at or above 0.5 mM, an individual is said to be in ketosis. Such a drastic reduction in carbohydrates and complete overhaul of one’s diet can be a bit overwhelming for some individuals.
As such, it might be best to slowly work your way to a ketogenic diet by first experimenting with low-carb diets where you’re only consuming 100-150 grams of carbs per day. Over the weeks, as you become more and more accustomed to eating low carb, you can eventually make the full transition to a keto diet and (hopefully) experience less of the quintessential “keto flu” symptoms.
Benefits of Ketosis
Being in a state of nutritional ketosis may:
● Reduce blood sugar (as measured by HbA1c),
● Improve insulin sensitivity (as measured by HOMA-IR)
● Lower inflammation (as measured by white blood cell count and C-reactive protein)
● Improve cholesterol levels
● Support weight loss
● Potentially reduce seizures
● Increase longevity and lifespan (in rodents)
● Reduce risk of cancer
Now, it should be noted, these benefits are not exclusive to ketogenic diets, or being in a state of ketosis. Similar benefits are also found when individuals lose weight, achieve a healthy body composition, and live an active lifestyle.
This is why long-term trials show that low-carb diets may initially lead to greater weight loss than low-fat diets, but the differences evaporate by the one-year mark.
Side Effects of Ketosis
Transitioning to ketosis isn’t all rainbows and sunshine, especially if you’re someone who’s used to consuming copious quantities of carbohydrates each day. During the initial days of your foray into ketogenic dieting, you may experience symptoms of “keto flu”, which include:
● Brain fog
● Difficulty concentrating
● Muscle aches
The reason for this is multifactorial, and two of the biggest contributors to keto flu appear to be a bit a metabolic “inflexibility” coupled with a severe loss of electrolytes. You see, when the body doesn’t get the amount of carbohydrates it is used to receiving each day, the liver starts pulling from glycogen (the storage form of glucose) for energy via gluconeogenesis. Eventually, the liver won’t be able to create enough glucose to satisfy the energy demands of the body, at which point the body has to turn to its back up fuel source — fatty acids.
However, if you’re an individual who has routinely lived a high-carb lifestyle and/or hasn’t experimented much with fasting, it’s likely that your body may need some time to “recalibrate” and get its metabolic machinery in order to start burning fat at the rate needed to maintain stable energy levels.
Other short-term side effects that may occur during the initial days of transitioning to a ketogenic diet are:
● Bad breath
● Muscle weakness
● Low blood sugar
● Difficulty sleeping
● Decreased exercise performance
To minimize the possibility of experiencing these symptoms, first try experimenting with a low-carb diet for a few weeks and/or periods of intermittent fasting, so as to help your body get used to burning fat more regularly in the absence of dietary carbohydrate. Additionally, going on a low-carb or ketogenic diet can create significant shifts in the water and mineral balance of the body. As such, it would be prudent to keep a close eye on your water and electrolyte intake daily, particularly regarding potassium and magnesium.
Lastly, the ketogenic diet is known to confer a high degree of satiety to some individuals, causing them to drastically under eat the first few days into the diet (which might be great for fat loss), but can also contribute to irritability and low energy levels. Therefore, make sure you’re consuming enough total calories each day to support your body’s energy requirements.
The keto diet is a high-fat, adequate-protein, and low-carbohydrate diet originally developed as a treatment for epilepsy. These days the diet is popular with those seeking to improve their metabolic health and body composition.
While the keto diet does come with a number of benefits (weight loss, improved metabolic profile, etc.), most (if not all) of the benefits can be obtained by leading an active lifestyle and maintaining a healthy body composition.
In other words, carbohydrates do not need to be completely eliminated from the diet in order to lose weight or be healthy. That being said, the main predictor of weight loss success is dietary adherence, meaning a diet is only as effective as your ability to stick to it.
If you find that you’re able to stay on track with your nutrition plan more closely when following a ketogenic diet, then have at it, and do what works best for you. Conversely, if you find greater satiety from including a variety of nutrient-dense, fibrous carbs in your diet (fruits, vegetables, and whole grains), then go for it.
At the end of the day, there is no perfect diet for every person in every situation. If keto works for you now, then use it to your advantage, and if it stops being sustainable down the road, don’t be afraid to do some self-experimentation and find a new pattern of eating that helps you meet your performance and physique goals.
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