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Ketosis: What Is Ketosis?
Written by James McIntosh
Reviewed by Dr Helen Webberley
Knowledge center
Last updated: Thu 1 October 2015

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Ketosis is a metabolic process that occurs when the body does not have enough glucose for energy. Stored fats are broken down for energy, resulting in a build-up of acids called ketones within the body.
Some people encourage ketosis by following a diet called the ketogenic or low-carb diet. The aim of the diet is to try and burn off unwanted fat by forcing the body to rely on burning fat for energy, rather than carbohydrates.
Ketosis is also commonly observed in patients with diabetes, as the process can occur if the body does not have enough insulin or is not using insulin correctly. Problems associated with extreme levels of ketosis are more likely to develop in patients with type 1 diabetes compared with type 2 diabetes patients.

In normal circumstances, the body’s cells use glucose as their main form of energy. Glucose is typically derived from dietary carbohydrates, including sugar and starchy foods such as bread and pasta which the body breaks down into simple sugars. Glucose can either be used to fuel the body or stored in the liver and muscles as glycogen.1
If there is not enough glucose available to meet energy demands, the body will adopt an alternative strategy in order to meet those demands. Specifically, the body begins to break down fat stores to provide glucose from triglycerides. Ketones are a by-product of this process.

Ketones are acids that build up in the blood and are eliminated in urine. In small amounts, they serve to indicate that the body is breaking down fat, but high levels of ketones can poison the body, leading to a process called ketoacidosis.2

Ketosis describes the metabolic state whereby the body converts fat stores into energy, releasing ketones in the process.3
The ketogenic diet
Some people follow a ketogenic diet as a way to lose weight.Due to the fact that ketosis breaks down fat stored within the body, some diets aim to create this metabolic state so as to facilitate weight loss.
Ketosis diets are also referred to as ketogenic diets, ket diets, or sometimes low-carbohydrate diets. The diet itself can be regarded as a high-fat diet, with around 75% of calories derived from fats. In contrast, around 20% and 5% of calories are gained from proteins and carbohydrates respectively.4
Adhering to the ketogenic diet can lead to short-term weight loss. A study conducted in 2008 and published in the American Journal of Clinical Nutrition found that obese men following a ketogenic diet for 4 weeks lost an average of 12 lbs during this time. The participants were able to consume fewer calories without feeling hungry while following the diet.5

According to the Mayo Clinic, the ketogenic diet could have a healthful effect on serious health conditions such as cardiovascular disease, diabetes and metabolic syndrome. It may also improve levels of HDL cholesterol better than other moderate-carbohydrate diets. 6
These health benefits could be due to the loss of excess weight and eating of healthier foods, rather than a reduction in carbohydrates.

The ketogenic diet has also been used under medical supervision to reduce seizures in children with epilepsy who do not respond to other forms of treatment. Some studies have suggested that the diet could also benefit adults with epilepsy, although more research is required to confirm these findings.7,8
However, longer-term adherence to the ketogenic diet does not appear to yield great benefit. A 2014 review of diets found that after a year, the difference between a ketogenic diet and a normal protein diet was only around 1 lb (roughly 0.4 kg).

The American Heart Association (AHA), American College of Cardiology, and the Obesity Society have concluded that there is not enough evidence to suggest that low-carbohydrate diets such as the ketogenic diet provide benefits healthful to the heart.

Ketosis and diabetes In diabetic patients, ketosis can occur due to the body not having enough insulin to process the glucose in the body. The presence of ketones in the urine is an indicator that a patient’s diabetes is not being controlled properly. 2
Some dietitians recommend a ketogenic diet for individuals with type 2 diabetes, also known as non-insulin dependent diabetes (NIDDM). With type 2 diabetes, the body still produces some insulin but is unable to properly use the insulin to transport glucose into cells for use as fuel.

The ketogenic diet focuses on the reduction of dietary carbohydrate intake. Individuals with type 2 diabetes are recommended to reduce carbohydrate intake as carbohydrates are converted to glucose and increase blood sugar levels.9
Patients with diabetes who follow a ketogenic diet need to carefully monitor their ketone levels. A serious condition called ketoacidosis can occur if these levels get too high, and although it is most prevalent in individuals with type 1 diabetes, people with type 2 diabetes can still develop ketoacidosis.

More on this article can be found at


Andros, Pete: “Using the Keto Diet Effectively for Health & Performance.” THEMANCANCOOK. N.p., 29 Aug. 2015. Web. 17 Sept. 2015. .


Emmerich, Maria: “Intermittent Fasting.” Maria Mind Body Health. Maria Emmerich, 08 May 2014. Web. 17 Sept. 2015. http://mariamindbodyhealth. com/intermittent-fasting