Ketogenic Diets (more specifically Cyclic Ketogenic Diets) are the most effective diets for achieving rapid, ultra low body-fat levels with maximum muscle retention! Now, as with all such general statements there are circumstantial exceptions. But done right – which they rarely are – the fat loss achievable on a ketogenic diet is nothing short of staggering! And, despite what people might tell you, you will also enjoy incredible high energy and overall sense of well being.
Despite these promises, more bodybuilders/shapers have had negative experiences then have seen positive results. The main criticisms are:
- Chronic lethargy
- Unbearable hunger
- Massive decrease in gym performance
- Severe muscle loss
All of these criticisms result from a failure to heed the caveat above: Ketogenic Diets must be done right! It must be realized that they are an entirely unique metabolic modality that adheres to none of the previously accepted ‘rules’ of dieting. And there is no going half-way; 50 grams of carbs per day plus high protein intake is NOT ketogenic!
So how are ketogenic diets ‘done right’? Let’s quickly look at how they work.
Overview of Ketosis
Simply, our body, organs, muscles and brain can use either glucose or ketones for fuel. It is the function of the liver and pancreas (primarily) to regulate that fuel supply and they show a strong bias toward sticking with glucose. Glucose is the ‘preferred’ fuel because it is derived in abundance from the diet and readily available readily from liver and muscle stores. Ketones have to be deliberately synthesized by the liver; but the liver can easily synthesize glucose (a process known as ‘gluconeogenesis’ that uses amino acids (protein) or other metabolic intermediaries) too.
We don’t get beta hydroxybutyrate, acetone, or acetoacetate (ketones) from the diet. The liver synthesises them only under duress; as a last measure in conditions of severe glucose deprivation like starvation. For the liver to be convinced that ketones are the order of the day, several conditions must be met:
- Blood glucose must fall below 50mg/dl
- Low blood glucose must result in low Insulin and elevated Glucagon
- Liver glycogen must be low or ’empty’
- A plentiful supply of gluconeogenic substrates must NOT be available
How it Works
When ketosis is sufficiently strong and lasts a while, your brain takes in monocarboxylate transporters which cause an uptake of ketone bodies from your blood. Both glia and neurons gather and oxidize ketone bodies, which forces the uptake to be directly related to the concentration within your blood. It should be highlighted at exact stages of development, the ketone bodies will be used not just as a metabolic substrate, rather, “as a source of acetyl-CoA that is a precursor to myelin, especially during early development, when brain myelin synthesis is extremely high.” It is noteworthy in this regard that the relatively high fat content of maternal milk favors ketosis.
At this point it is important to mention that it is not actually a question of being ‘in’ or ‘out’ of ketosis; we don’t either totally run on ketones, or not. It is a gradual and careful transition so that the brain is constantly and evenly fueled… ideally. Ketones SHOULD be produced in small amounts from blood glucose levels of about 60mg/dl. We consider ourselves in ketosis when there are greater concentrations of ketones than glucose in the blood.
The reality is that most people – especially weight trainers – have had a regular intake of glucose for a good couple of decades, at least. The liver is perfectly capable of producing ketones but the highly efficient gluconeogenic pathways are able to maintain low-normal blood glucose above the ketogenic threshold.
Couple this with the fact that many people are at least partially insulin resistant and have elevated fasting insulin (upper end of the normal range, anyway). The small amount of blood glucose from gluconeogenesis induces sufficient insulin release to blunt glucagon output and the production of ketones.
Sudden glucose deprivation will have the consequence, initially, of lethargy, hunger, weakness etc in most people – until ketosis is achieved. And Ketosis will not be reached until the liver is forced to quit with gluconeogenesis and start producing ketones. As long as dietary protein is sufficient then the liver will continue to produce glucose and not ketones. That’s why no carb, high protein diets are NOT ketogenic.
 – Diapedia.org, “Amino acid metabolism”, https://www.diapedia.org/metabolism-and-hormones/5105758814/amino-acid-metabolism
 – Medical Daily, “Ketogenic Diet Facts: How Long Will It Take To Enter Ketosis?”, https://www.medicaldaily.com/ketogenic-diet-facts-how-long-will-it-take
 – National Library of Health, “The Ketogenic Diet and Brain Metabolism of Amino Acids: Relationship to the Anticonvulsant Effect”, https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4237068/
 Medical News Today, “How to Get Into Ketosis Fast’, https://www.medicalnewstoday.com/articles/324599.php