Ketosis 101

Posted by Josh Gape on

The ketogenic revolution is here. Elite athletes from all corners of the world are feeling the benefits of cutting the carbohydrates and embracing fats as part of their nutritional plan. But what exactly is ketosis, and why is it right for you? APE Nutrition founder Josh Gape has you covered with Ketosis 101. 



Ketosis is a metabolic state, in which a person’s body utilises fat and ketones as its primary fuel sources as opposed to glucose. 



Carbohydrate based diets have been used in sport since the dawn of the professional era, but is there a better fuel source out there? Athletes who have converted to keto report improvements in strength, power, endurance, cognitive abilities and recovery as well as a host of health benefits.


  • Increased Strength & Power 

Ketosis has been shown to be an effective tool for losing fat and gaining muscle – depending on the individual and their total caloric intake. It remains to be proven whether a ketogenic diet is as effective at building muscle mass as a carbohydrate rich diet. However, we do know that the ketogenic diet can improve your body composition and strength / power to weight ratio. 

For example, if you’re a powerlifter and compete in the 93kg weight class, becoming keto adapted will help you decrease body fat and lose water weight. As a result you can gain additional muscle mass whilst remaining in your weight category and therefore increase your strength potential. The more muscle mass you have, the greater your ability to lift heavy weight. The same is true for power potential and Olympic weightlifters. 


  • Increased Endurance 

Keto-adaption appears to have the greatest potential to revolutionise endurance sports. Carb loading before a marathon, long ride or triathlon fills the body’s glycogen stores with 400 – 500g of energy, which is regularly topped up during competition with sugary drinks and gels. 

Athletes who switch-up their energy source have the potential to finish stronger than their rivals. Lean individuals can store around 40,000 calories (4,444g) of fat in cells called adipocytes. When endurance training, an athlete will primarily use their aerobic energy system, which relies on fat for fuel. So for an endurance athlete, becoming keto-adapted means your energy store will increase by 20 times at least, from 2,000 to 40,000 calories. Say goodbye to hitting the wall.


  • Increased Cognitive Abilities 

Our brains have the ability to utilise glucose and ketones for energy. As with our muscles, when eating a carbohydrate rich diet, glucose will be the brain’s main fuel source. However, when carbohydrates are restricted, ketones become the brains primary source of energy. It is widely reported (and I can confirm from my experiences) that this has powerful effects on cognition. This is because, ketone bodies have been shown to provide more energy per unit of oxygen consumed and they metabolise faster than glucose. Also, as with endurance training, ketones provide a longer lasting, more stable, energy supply. This all combines to produce a Zen like focus, which is sustained throughout the day. No more post lunch energy crashes. 


  • Increased Recovery 

Athletes on a ketogenic diet often report rapid recovery times. The prevailing theory behind this, is that when fat is burned for fuel, as opposed to carbohydrates, less reaction oxygen species (aka oxygen free radicals) are created. These molecules damage membrane polyunsaturated fats and tissue proteins, resulting in inflammation. When fewer are created during exercise, individuals experience less inflammation, soreness and muscle damage. As a result, they are able to perform optimally sooner without feeling the effects of their last workout.



Fat-adaptation can be achieved through the ketogenic diet, fasting and / or the consumption of exogenous ketones in the form of ketone esters or ketone salts.  

To achieve nutritional ketosis through diet, you must eat a high amount of fat (70% of daily calories), moderate amounts of protein (25%) and a small amount of carbohydrate (5%).


Every person is unique, however, generally speaking, once you’ve followed this diet strictly for around two weeks your body begins to adapt. In the absence of carbohydrates you begin to break down stored and dietary fat into ketone bodies and use these as your primary fuel source. This will result in the presence of ketones in your blood. When your blood ketones reach 0.5mmol/l or over, you’re considered to be in nutritional ketosis. 

If you’re interested on how exactly this can be achieved, I’ve written a detailed guide on how to transition in to ketosis here.