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.
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”.
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;
- 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.
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
Alzheimer’s disease is one of the most terrible modern diseases, and it is one that devastates families both emotionally and financially.
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.
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.
- 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.
3) Ketone Bodies, Hunger, and 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?
- 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.
4) Reduced Triglycerides and Increased HDL
The triglyceride to HDL ratio is one of the most reliable predictors of cardiovascular risk.
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.
5) Ketone Bodies and Mental Health/Conditions
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).
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.