What Is Ketogenesis and What Are Ketone Bodies?

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The Structure of Ketone Bodies: Acetone, Acetoacetate and 2-Hydroxybutyric Acid.With heavy coverage in the media, low carb and ketogenic diets are all the rage right now.

And for a good reason; for some people, they truly work.

But what do all these different terms like ketogenesis and ketone bodies actually mean?

Firstly, this article takes a look at what the ketogenesis pathway is and what ketone bodies do.

Following this, it will examine six potential health benefits of ketones and nutritional ketosis.

What is Ketogenesis?

Ketogenesis is a biochemical process through which the body breaks down fatty acids into ketone bodies (we’ll come to those in a minute).

Synthesis of ketone bodies through ketogenesis kicks in during times of carbohydrate restriction or periods of fasting. When carbohydrate is in short supply, ketones become the default energy source for our body.

As a result, a diet to induce ketogenesis should ideally restrict carb intake to a maximum of around 50 grams per day (1, 2).

Ketogenesis may also occur at slightly higher levels of carbohydrate intake.

When ketogenesis takes place, the body produces ketone bodies as an alternative fuel to glucose.

This physiological state is known as ‘nutritional ketosis’ – the often default state of people following ketogenic diets.

There are various methods you can use to test if you are “in ketosis”.

Key Point: Ketogenesis is a biological pathway that breaks fats down into a form of energy called ketone bodies.

What Are Ketone Bodies?

Ketone bodies are water-soluble compounds that act as a form of energy in the body.

There are three major types of ketone body;

  • Acetoacetate
  • Beta-hydroxybutyrate
  • Acetone (a compound created through the breakdown of acetoacetate)

The first thing to remember is that these ketones satisfy our body’s energy requirements in the same way that glucose does.

However, unlike glucose, ketone bodies have no impact on blood sugar or insulin levels.

Although we often hear that carbohydrate is “essential” for energy, our body can meet its energy needs through fat too.

Note: This doesn’t mean all carbs are inherently bad for you; they aren’t. 

Key Point: Ketone bodies are an alternative source of fuel that the body can use for energy. Ketones are produced from the breakdown of fat.

Potential Health Benefits of Ketosis

Firstly, the process of ketogenesis and the subsequent production of ketones changes the whole way in which our body operates.

After adapting to ketosis, the body starts using ketones for energy rather than glucose, and this may have some positive benefits.

This article will focus on six of these potential benefits.

For any concerns around ketones and ketoacidosis, see this guide to ketogenic diets and ketoacidosis.

1) Ketone Bodies May Help Treat Alzheimer’s Disease

Picture of a Confused Elderly Lady Possibly With Dementia.Alzheimer’s disease is one of the most terrible modern diseases, and it is one that devastates families both emotionally and financially.

The idea has been around for some time, but recent research suggests that Alzheimer’s may be a form of diabetes. Some researchers have even given it the tentative name of ‘type 3 diabetes’ (3, 4).

In other words, they are referring to Alzheimer’s as insulin resistance of the brain.

The idea is that the condition is similar to type 2 diabetes, where our body becomes resistant to insulin; the only difference is that with Alzheimer’s it happens in the brain (5).

Insulin resistance signifies that we cannot metabolize carbohydrate correctly, and so our brain becomes starved of energy (glucose).

This results in;

  • Glucose building up in the brain (hyperglycemia) and causing oxidative stress/damage
  • Brain cells starve and die as they cannot utilize energy (glucose) at a sufficient rate

Can Ketones Provide an Alternative Fuel For the Damaged Brain?

This research examines the idea that the Alzheimer’s brain cannot adequately function on glucose.

However, through ketogenesis, the body can produce ketone bodies that provide a source of energy that the brain can utilize.

This shouldn’t be taken to mean “low carb diets cure Alzheimer’s”, but they may potentially play a therapeutic role to help treat the disease.

There are numerous studies in this area—some of which are still ongoing—that find;

  • “A ketogenic diet is a safe intervention that is well supported by science to bypass the brain’s deteriorating usage of energy”. However, whether it can limit the onset or progression of Alzheimer’s is not known at this time (6).
  • Ketones have a neuroprotective mechanism in which they block amyloid, a kind of plaque that builds up in the brain in Alzheimer’s cases (7).
  • Ketone bodies show benefit in both animal and human clinical trials, but it is a new area of research. Additionally, a randomized controlled trial demonstrates that Alzheimer’s patients taking a ketone supplement show improved cognition (8, 9).

Hopefully, future research in this area may lead to better treatment options.

Key Point: The brain is able to use ketone bodies as a replacement fuel for glucose. As a result, a diet that induces ketosis may hold promise for limiting the progression of Alzheimer’s disease.

2) Reliably Reduces Blood Glucose and Insulin Levels

Being in ketosis reliably reduces blood glucose and insulin levels.

However, why does reducing our blood sugar and insulin have benefits?

First, there is a difference between short-term insulin release (natural) and chronic high fasting insulin levels.

Higher fasting blood glucose and hyperinsulinemia (constantly elevated insulin levels) have links to most chronic diseases.

For example:

  • Hyperinsulinemia has links to increased cancer mortality independently of diabetes. In other words, high fasting blood sugar and insulin levels are damaging to everyone — whether diabetic or not (10).
  • A large number of studies support the association between type 2 diabetes with cancer risk and mortality (11).
  • Higher fasting insulin levels result in more pro-inflammatory effects, and there are close links between hyperinsulinemia and vascular diseases such as cardiovascular disease (12).
  • Hyperinsulinemia is involved in the pathways of most modern disease (13).

There are various ways to reduce blood sugar/insulin, and it is not only a nutritional consideration – exercise, sleep and even stress all play a role.

As always, there is not only one diet that can help in this regard either.

That said, ketogenic diets are a recognized option to reduce fasting blood-glucose and insulin levels.

Key Point: Fasting levels of glucose and insulin fall when people enter ketosis.

3) Ketone Bodies, Hunger, and Food Cravings

Picture of a lady with food cravings.Ultra-processed foods that quickly spike blood sugar levels generally leave us feeling hungry a few hours later.

For some people, fighting the temptation to eat these foods is a daily battle.

However, some followers of the ketogenic diet claim that they can effortlessly go all day without eating, and this makes losing weight easier.

So, why, in some cases, does this happen?

Is it the satiating effect of protein? This probably plays a significant part.

But is there something else going on too?

Can the Presence of Ketones Directly Suppress Appetite?

Some studies have looked into this area, and there are several interesting—but inconclusive—points to consider (14, 15, 16);

  • The ‘hunger hormone’ ghrelin typically rises during weight loss and increases food cravings. However, in a recent study, this increase was suppressed in dieters in ketosis, despite a caloric deficit.
  • In the same study, the satiety hormones leptin and amylin rose despite the participants losing weight. After reintroducing carbohydrate, satiety hormones fell, and hunger hormones quickly increased.
  • A high presence of ketone bodies may provide a signal to inhibit the body’s production of hunger hormones.
  • A meta-analysis and systematic review of available trials suggest appetite suppression through ketosis is plausible. However, a ‘minimal level of ketosis‘ may be required to achieve this effect.
Key Point: Personally, I think the satiety benefits of low carb diets come predominantly from the higher protein intake. However, tentative research suggests that ketone bodies may help to suppress appetite directly.

4) Reduced Triglycerides and Increased HDL

Ketone Bodies Reduce Triglycerides and Increase HDL.The triglyceride to HDL ratio is one of the most reliable predictors of cardiovascular risk.

Firstly, it is unarguable that LDL is associated with cardiovascular disease (17, 18).

However, some researchers believe that the ratio of triglycerides to HDL is a more reliable marker (19).

There are some studies that support this theory too;

  • A 2015 study found that the triglyceride to HDL ratio is the most significant independent marker of cardiovascular mortality (20).
  • In a study involving 374 high-risk heart patients, there was no significant relationship between total cholesterol and the extent of coronary disease. Additionally, there was an extremely significant statistical link from total triglycerides and the triglyceride/HDL ratio (21).

How Does Being in Ketosis Affect HDL/Triglycerides?

A low level of HDL and a high amount of circulating triglycerides reliably track with high amounts of insulin in the blood (22).

In other words, when we reduce our blood glucose levels, insulin typically falls, and the HDL/triglyceride ratio improves.

The scientific literature generally shows that ketogenic diets favorably impact cardiovascular risk;

  • In a study of obese subjects, a sub-20-gram carbohydrate ketogenic diet decreased total cholesterol, LDL cholesterol, triglycerides, and blood glucose. In contrast, there was a significant increase in HDL. This study lasted 56 weeks, and health markers were consistent through seven different tests at eight-week intervals (23).
  • A 6-week study of healthy weight men showed that a ketogenic diet of 8% carbohydrate significantly increased HDL levels without impacting LDL or total cholesterol (24).

However, it is worth noting that LDL levels can rise in some individuals, likely dependent on the diet’s formulation.

Key Point: Lower triglycerides and higher HDL appear to reduce the risk of heart disease. When the body is in ketosis, the triglyceride/HDL ratio usually improves.

5) Ketone Bodies and Mental Health/Conditions

A Healthy Looking Young Man.

There is a notable amount of anecdotal evidence regarding ketogenic diets and mental health.

In particular, many people claim that entering ketosis improved their mental clarity, focus, eliminated brain fog, and relieved depression.

But is this just anecdotal, or is there science behind it too?

  • Following ketogenesis, intracellular sodium concentrations fall as the body enters ketosis. Significantly, this is the same effect that all mood stabilizers have (25).
  • In human subjects, a randomized, controlled trial found that a low carbohydrate diet induces a statistically significant improvement in mood. Compared to a low-fat intervention group, the low-carb dieters also experienced fewer mood swings and irritability (26).
  • In animal studies, rats feeding on a ketogenic diet displayed fewer symptoms of depression than those on a control diet. These rats also exhibited the same improvements in positive behavior as rats treated with antidepressants (27).
  • Prenatal exposure to a ketogenic diet reduces anxiety, depression, and blood glucose levels as an adult (animal study) (28).
  • Four randomized, controlled trials involving 289 people show that ketogenic diets may be beneficial for epilepsy patients. In brief, the studies show that being in ketosis provides short to medium term benefits in seizure control (29).
Key Point: After the induction phase of ketogenesis, the brain can switch to using ketone bodies for fuel. A decent amount of research suggests that this may lead to improvements in depression and mental state.

Final Thoughts

As shown in this article, ketone bodies and being in ketosis could have several benefits.

However, the most important thing to remember is that all diets are just the sum of their parts.

Any diet that proves sustainable and helps to improve your daily dietary choices will have positive health effects.

No matter what type of eating plan you favor, the important thing is to primarily focus on whole, unprocessed foods.

To put it differently, whether a ketogenic diet is healthy or not depends on the quality of foods you are including.

For further information, see this guide to formulating a healthy ketogenic diet.

To see more related articles, read this guide to ketogenic diets and sporting performance.

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Ravindra Babu BIma RifiyantiWienWiwiek SulemanTom Recent comment authors
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Ravindra Babu B
Ravindra Babu B

I am diabetic and i started to take keto diet a month and four ago. My HBA1C dropped from 7.0 yo 5.9 in this short time. But my lipids are sky rocketing. Triglycerides Jumped to 352 from 200. Total cholesterol jumped ftom 185 to 412. But isn’t this contrary to what you said like it will improve triglycerides to HDL ratio? Of course my HDL went upto 46 frm 34. But still the ratio moved to the wrong side. Coild you please throw some light on this?

Ima Rifiyanti

please tell more about the most important thing in keto diet is about whole and unprocessed food. What kind of food that could be negative effect in keto diet ?


Thank you for the insightful information. However, you only listed the positive effects of ketone body. Are there any negative effects?

Wiwiek Suleman
Wiwiek Suleman

This topic is very good, thank you.


What about acidosis and resulting complications dehydration, hypotension and shock…..?????…..

Kari Pratt
Kari Pratt

So, how can I tell if I am in ketosis?