Updated: Feb 1
As mentioned before in one of my articles on an understanding of weight loss and the physiology of exercise, I will always encourage my readers to gain as much knowledge as possible about certain physiological mechanisms related to weight loss before embarking, blindly, to follow that regimen.
There are scores of blogs, which I have visited and read their articles, which are exercising keto-diet, but without a complete understanding of this word along with the Physiology of its metabolism, I will strongly discourage opting for it.
In the layman terminology – “The ketogenic diet is a very low carb, a high-fat diet that shares many similarities with the Atkins and low carb diets.”
But, as one can see from the above definition it does not put enough light as to what it is. We, therefore, have to go deep into its definition along with the understanding of the Physiology associated with it.
“The ketogenic diet is a high-fat, adequate-protein, low-carbohydrate diet that in medicine is used mainly to treat hard-to-control (refractory) epilepsy in children. The diet forces the body to burn fats rather than carbohydrates.”
Low-carbohydrate diets restrict carbohydrate consumption relative to the average diet. Foods high in carbohydrates (e.g., sugar, bread, pasta) are limited and replaced with foods containing a higher percentage of fat and protein (e.g., meat, poultry, fish, shellfish, eggs, cheese, nuts, and seeds), as well as low carbohydrate foods (e.g. spinach, kale, chard, collards, and other fibrous vegetables).
There is a lack of standardization of how much carbohydrate low-carbohydrate diets must-have, and this has complicated research. One definition, from the American Academy of Family Physicians, specifies low-carbohydrate diets as having less than 20% carbohydrate content.
So keto-diet means to reduce your carbohydrate intake as much as possible and replace that with protein and fats. As far as proteins are concerned, all proteins are chemically the same, so doesn’t matter what type of protein, but when talking about fats, there are many different kinds of fats. Grossly, animal and plant fats. Most animal fats are involved in the production of atherosclerosis and hence constriction of small arteries supplying essential organs.
This article is not about the use of the keto-diet, I will just discuss the benefits if any, and the risks associated with it.
Body Energy Concept
I will once again refer the readers to my article on details of the physiology of different nutrients and how they are metabolized in the body. Suffice here is to say that, all energy-producing nutrients, i.e., carbohydrates, fats, and proteins can be used inside the body for the production of energy currency, i.e., ATP. All carbohydrates we eat will be converted into glucose either before absorption or after absorption in the liver. Thus glucose is the ultimate source of production of ATP. In the presence of insulin, all cells can utilize glucose. All excess glucose is converted to either glycogen and/or fats and stored appropriately, in the presence of insulin. But, when insulin is not there, only neurons and exercising skeletal muscles can utilize glucose. Hence, the stored glucose will be broken down and released into the blood along with the release of fats for energy and the making of new glucose from the fats. Proteins are generally sparred whenever glucose and fats are abundant.
Theoretically, if you do not supply the body with glucose, it will be forced to use fats for the production of energy.
How fats are used for energy?
The dietary intake of fat varies considerably in persons of different cultures, averaging as little as 10 to 15 percent of caloric intake in some Asian populations to as much as 35 to 50 percent of the calories in many Western populations. For many persons, the use of fats for energy is therefore as important as the use of carbohydrates is. Besides, many of the carbohydrates ingested with each meal are converted into triglycerides, then stored, and used later in the form of fatty acids released from the triglycerides for energy.
Almost all cells—with some exceptions, such as brain tissue and red blood cells—can use fatty acids for energy. A large share of the initial degradation of fatty acids occurs in the liver, especially when excessive amounts of lipids are being used for energy. when the fatty acid chains have been split into acetyl-CoA, two molecules of acetyl-CoA condense to form one molecule of acetoacetic acid, which is then transported in the blood to the other cells throughout the body, where it is used for energy. Part of the acetoacetic acid is also converted into b-hydroxybutyric acid, and minute quantities are converted into acetone. These three chemicals are ketone bodies. They will always be generated with fats as the primary source of energy.
Ketosis in Starvation, Diabetes, and Other Diseases
The concentrations of acetoacetic acid, β-hydroxybutyric acid, and acetone occasionally rise to levels many times normal in the blood and interstitial fluids; this condition is called ketosis because acetoacetic acid is a keto acid. The three compounds are called ketone bodies. Ketosis occurs especially in starvation, in diabetes mellitus, and sometimes even when a person’s diet is composed almost entirely of fat. In all these states, essentially no carbohydrates are metabolized—in starvation and with a high-fat diet because carbohydrates are not available, and in diabetes, because insulin is not available to cause glucose transport into the cells.
When carbohydrates are not used for energy, almost all the energy of the body must come from the metabolism of fats. The unavailability of carbohydrates automatically increases the rate of removal of fatty acids from adipose tissues; besides, several hormonal factors—such as increased secretion of glucocorticoids by the adrenal cortex, increased secretion of glucagon by the pancreas and decreased secretion of insulin by the pancreas—further enhance the removal of fatty acids from the fat tissues. As a result, tremendous quantities of fatty acids become available (1) to the peripheral tissue cells to be used for energy and (2) to the liver cells, where much of the fatty acid is converted to ketone bodies.
The ketone bodies pour out of the liver to be carried to the cells. For several reasons, the cells are limited in the number of ketone bodies that can be oxidized; the most important reason is the following: One of the products of carbohydrate metabolism is the oxaloacetate that is required to bind with acetyl-CoA before it can be processed in the citric acid cycle. Therefore, deficiency of oxaloacetate derived from carbohydrates limits the entry of acetyl-CoA into the citric acid cycle, and when there is a simultaneous outpouring of large quantities of acetoacetic acid and other ketone bodies from the liver, the blood concentrations of acetoacetic acid and β-hydroxybutyric acid sometimes rise to as high as 20 times normal, thus leading to extreme acidosis.
Adaptation to a High-Fat Diet
When changing slowly from a carbohydrate diet to an almost completely fat diet, a person’s body adapts to use far more acetoacetic acid than usual, and in this instance, ketosis normally does not occur. For instance, the Inuit (Eskimos), who sometimes live mainly on a fat diet, do not develop ketosis. Undoubtedly, several factors, none of which is clear, enhance the rate of acetoacetic acid metabolism by the cells. After a few weeks, even the brain cells, which normally derive almost all their energy from glucose, can derive 50 to 75 percent of their energy from fats.
Facts and Fantasy
An extreme form of low-carbohydrate diet – the ketogenic diet – was first established as a medical diet for treating epilepsy. Through celebrity endorsement, it has become a popular weight-loss fad diet, but there is no evidence of any distinctive benefit for this purpose, and it carries a risk of adverse effects. The British Dietetic Association named it one of the "top 5 worst celeb diets to avoid in 2018".
Below is an excerpt from the page of BDA, readers are advised to visit the site.
The British Dietetic Association (BDA) today (7-Dec-2017) revealed its much-anticipated annual list of celebrity diets to avoid in 2018. The line-up this year includes Raw Vegan, Alkaline, Pioppi, and Ketogenic diets as well as Katie Price’s Nutritional Supplements.
Celeb Link: A plethora of celebs have been linked with this diet including Kim Kardashian, Kobe Bryant, LeBron James, Halle Berry, Gwyneth Paltrow, Mick Jagger, Rihanna, Alec Baldwin, Matthew McConaughey, Tom Jones.
What is it? This diet, is out there in many versions rather like Atkins or Paleo but the premise is the same: very low carb (around 20-50g per day or 5% total calories), relatively high in fat, moderate protein. Typically, it excludes grains, dairy, legumes, soy, most fruits, and starchy vegetables. The carbohydrates in the diet come mainly from non-starchy vegetables, nuts, and seeds.
If you significantly decrease the number of carbohydrates in your diet, the body switches from primarily burning carbohydrates, to burning fat, for energy. This causes an increase in levels of ketones in our bodies. Supporters claim it can help you to lose weight, control hunger, and improve your health. Worryingly some say it can treat or prevent several different types of cancer which are just not true.
BDA Verdict: A carefully dietitian-planned ketogenic diet can be a very effective treatment for people with epilepsy. For weight loss, there’s no magic, the diet works like any other by cutting total calories and removing foods people tend to overeat. Initial side effects may include low energy levels, brain fog, increased hunger, sleep problems, nausea, digestive discomfort, bad breath, and poor exercise performance. It can be an effective method of weight loss in the short term with careful planning but it is hard to sustain for many in the long term and most of the initial weight loss seen is often associated with water/fluid losses. It is never a good idea to ‘over-restrict’ any one food group (including carbohydrate), as this can mean it is more difficult to achieve a balanced diet overall concerning vitamins, minerals, and fiber in particular. If consuming high fat then the type of fat needs to be considered.
Bottom line: May suit some but ketone-ly with careful planning for balance, heart, and gut health.
What experts are saying?
The keto diet could cause low blood pressure, kidney stones, constipation, nutrient deficiencies, and an increased risk of heart disease. Strict diets like keto could also cause social isolation or disordered eating. Keto is not safe for those with any conditions involving their pancreas, liver, thyroid, or gallbladder.
Kleinman said someone new to the keto diet can also experience what’s called the “keto flu” with symptoms like upset stomach, dizziness, decreased energy, and mood swings caused by your body adapting to ketosis.
Eating a lower amount of carbohydrates on a ketogenic diet does not prevent the roller-coaster of sugar levels (refer to this site).
Once in ketosis, the body can draw energy from its fat stores and the liver can create as much glucose as the body needs -and not too much. As a result, by cutting out carbs, the body finds it easier to regulate sugar levels and energy.
A ketogenic diet could be an interesting alternative to treat certain conditions and may accelerate weight loss. But it is hard to follow, and it can be heavy on red meat and another fatty, processed, and salty foods that are notoriously unhealthy. We also do not know much about its long-term effects, probably because it’s so hard to stick with that people can’t eat this way for a long time. It is also important to remember that “yo-yo diets” that lead to rapid weight loss fluctuation are associated with increased mortality. Instead of engaging in the next popular diet that would last only a few weeks to months (for most people that includes a ketogenic diet), try to embrace change that is sustainable over the long term. A balanced, unprocessed diet, rich in very colorful fruits and vegetables, lean meats, fish, whole grains, nuts, seeds, olive oil, and lots of water seems to have the best evidence for a long, healthier, vibrant life.
Guyton and Hall Textbook of Medical Physiology – Twelfth Edition