These days everyone seems to be talking about keto - ketogenic dieting, low-carb eating etc. At the same time, I noticed that a lot of people do not know what ketosis is or are completely misunderstanding this concept and confusing it with ketoacidosis. Today, we will clarify things once and forever. Prior to getting to ketosis itself, let's talk about ketone bodies, or ketones.
What are ketones?
Ketones are by-products of fat burning - fat is stored in a form of triglycerides, molecules created by attaching three fatty acids to glycerol. When we need to use them as fuel, these triglycerides are broken down into glycerol, which is metabolized as a carbohydrate (can be converted into glucose and used by the tissues that require glucose, such as red blood cells), and fatty acids. In order to use these fatty a
cids as a fuel source we need to cleave off chunks of the carbon chains of fatty acids - the "chunks" are called acetyl-CoA (Co-A stands for co-enzyme A), which in turn can lose their Co-A groups and when fused together form acetoacetate, our first ketone body. If acetoacetate is reduced it becomes β-hydroxybutiric acid (β-hydroxybutirate) and if acetoacetate is decarboxylated it becomes acetone. Thus, we have 3 types of ketones - acetone, β-hydroxybutirate and acetoacetate. As of note, when enough acetone is produced we can exhale it. In this case the breath has a "fruity" or "nail polish" odour, which is noticeable if someone is on a ketogenic diet, but also, it's a hallmark feature of diabetic ketoacidosis (more on it later). Now, when we know what ketones are, we are ready to proceed to all things keto.
What is ketosis?
Ketosis is a state of elevated ketones in the bloodstream. There are several conditions that lead to such elevation such as starvation, low carbohydrate intake, intense exercise, alcoholism and diabetes (we'll have a special discourse on it) to name a few. All these conditions have one thing in common - low levels of glucose getting into tissues - in case of starvation or low-carb dieting we simply do not get enough of it with our nutrition, in case of very intense exercise we use up all glucose from the bloodstream (there isn't much in general), then we mobilize the glycogen storages and use it up too and after that our body has to switch to fat as there is no more glucose left.
Is ketosis bad for you?
The short answer is no - unlike ketoacidosis, which we will discuss in a bit, it's just a normal, physiological state, a by-product of fat mobilization. Ketosis is simply the state when ketone bodies reach certain detectable level, which is a result of a slight lag between the ketone bodies production and uptake/utilization by tissues and occurs when our bodies switch to fat as the major source of energy. Intake of carbohydrates usually halts this process, unless you have diabetes or some other medical conditions preventing insulin release or it's proper functioning.
Does ketosis equate to weight loss?
The answer is no and this, actually, is the truth I wanted to share with you today. Again, ketosis is the by-product of fat burning, nothing more nothing less. The fat that is being converted into ketones doesn't have to be your body fat, it can and often is dietary fat. If you consume enough energy with your nutrition, you will still be able to burn fat and store fat at the same time. So, effectively ketosis is an indicator of fat burning, not obviously fat loss.
Is weight loss possible without being in ketosis?
Actually yes, but likely it will be a very modest weight loss. First of all, when we diet we don't lose only fat - we also lose water, glycogen, tissue proteins etc. Losing weight this way doesn't involve fat burning, so there will be no ketones and no ketosis. At the same time, you can still lose some small amounts of fat if you convert them into ketones, but their level in the bloodstream will be low, below the "ketosis level". At the same time, I'd like to point out that any intense fat loss will likely be associated with elevated levels of ketone bodies and thus - with ketosis.
What is ketoacidosis?
In case of diabetes the production of insulin is impaired and effectively our tissues cannot uptake glucose, even if there is a lot of it in the bloodstream. In such scenario, the tissues start mobilizing fat and large quantities of ketone bodies are released into the bloodstream. But there are two key differences between this scenario and diet- or exercise-induced ketosis: There is plenty of unused glucose in the bloodstream and this process if dysregulated as there is no insulin. As a result, this process, which is pathological, leads to production of high quantities of acidic metabolites that affect the pH of the blood and result in metabolic acidosis, which we call ketoacidosis since it is associated with high ketone concentrations. Again, this process is pathological and is cardinally different from diet- or exercise-induced ketone production and ketosis.
Can ketosis progress into ketoacidosis?
Theoretically, yes, it can and there are case reports of people having benign ketoacidosis due to low-carbohydrate diets1, but it's very unlikely in a healthy person, or in someone who has no pre-existing or concurrent endocrine problem as when ketones level reach certain point, our body slows down fat burning so that we can utilize the ketones that are already in the bloodstream. It would take an additional medical problem, like vomiting for example, to contribute to changes in pH resulting in ketoacidosis.
Summary
Fat loss results in production of ketones, which can lead to their increased concentration in the bloodstream, called ketosis. Ketosis is a normal, physiological process, which is very different from ketoacidosis, a pathological state, usually associated with diabetes. Ketosis is an indicator of fat burning, but it doesn't always equate to fat loss.
I hope that now we have clarified all the main aspects of ketosis and you can use this knowledge to chose your diet, to plan your nutrition and to evaluate your progress. If you have any further questions, by all means, please ask them, leave comments and check out my YouTube channel for more information.
Sincerely Yours,
Dr.Sam
Video: The TRUTH about Ketosis
References:
1. Shah P, Isley WL. Ketoacidosis during a Low-Carbohydrate Diet. 2006;354(1):97-98.