Ketones – healthful or harmful?

Nutritional Ketosis and Diabetic Ketoacidosis

Nutritional Ketosis and Diabetic Ketoacidosis

Dr. Sean Wheatley, PhD – Researcher and Trainer in Public Health/15 May 2017

The topic of ketones is seen as controversial by some. But this is largely due to a misunderstanding of what ketones are and what they do. This blog aims to give a summary of the subject. And hopefully clear up some of the confusion for the public and health care professionals alike.

What are ketones?

Ketones are natural. They are produced when fat is burned for energy. They themselves can be an excellent source of energy, especially for the brain. It is often quoted that the brain can only use glucose for energy, but it can actually get up to 80% of its energy from ketones.

Why are people worried about them?

When ketones are mentioned in relation to diabetes people think of diabetic ketoacidosis (DKA). DKA is a serious condition that can potentially be fatal. However, there is a massive difference between DKA and nutritional ketosis. Ketones themselves are not dangerous, except in extreme circumstances.

What is the difference between Nutritional Ketosis and Diabetic Ketoacidosis?

In nutritional ketosis both blood glucose and insulin levels are low, and the levels of ketones are typically not as high as those seen in DKA. This reflects that fat is being used as the main source of energy. Growing children, pregnant women and anyone on a weight reducing diet can be in nutritional ketosis. It is also seen in people who restrict their carbohydrate intake significantly. Carb consumption of less than 50g per day may be necessary to achieve nutritional ketosis. Some people may find it difficult to sustain a lifestyle that achieves this.

Although nutritional ketosis can actually have a positive effect on some peoples’ health (see below) DKA is a serious condition where ketone levels AND blood glucose levels are dramatically raised. It is these extreme levels of both ketones and glucose, in the presence of insulin insufficiency (when there is not enough insulin to move the glucose into the cells to be used for energy), that results in DKA. Ketones are acidic, so extremely elevated levels make the blood more acidic (hence “acidosis”).

Is nutritional ketosis a good thing?

People with diabetes struggle to use carbs properly. In Type 2 diabetes this is due to insulin resistance (insulin not working as well) and in Type 1 diabetes it is because of insulin insufficiency. Being in a state of nutritional ketosis, achieved through reducing carb intake*, can therefore be beneficial for people with Type 1 and Type 2 diabetes* as they are using fat rather than carbs as their preferred energy source. This reduces the requirement for insulin*, reduces the risk of hypos, and can help with body weight management.

Many people without diabetes are also insulin resistant to some extent. Which means their carbohydrate tolerance (how well their body can use carbs) can also be reduced. This is especially common in people who are overweight or obese. These people may therefore also see some benefits from being in nutritional ketosis, if it is a lifestyle that they find suitable (and many people do).

So what should my ketone levels be?

If blood glucose levels are high (above 11 mmol/l) then high ketone levels can be dangerous. In this case ketone levels above 3.0 mmol/l  would be considered high, and so you should take action. DKA is an emergency condition that only usually occurs in people with Type 1 diabetes. If you are experiencing the symptoms of DKA you should head straight to hospital for treatment.

If you are following a low carb diet or using some form of intermittent fasting your ketone levels are likely to be increased, as you may be in nutritional ketosis. Ketone levels between 0.5 and 3.0 mmol/ l would be considered normal in this instance. THIS IS NOT DANGEROUS AS LONG AS YOUR BLOOD GLUCOSE LEVELS ARE NOT ELEVATED.

So what’s the bottom line?

The bottom line is, if you don’t have insulin insufficiency and your glucose levels aren’t high then there is nothing wrong with having elevated ketone levels. Being in nutritional ketosis can be a positive thing for many people. so if it is a lifestyle you’re happy with (and many people are) there is nothing to be afraid of!

* Any lifestyle changes that reduce carbs and/or insulin requirements may well mean that anyone on insulin has to change their dose and/or regimen, and can also affect any other meds they may be on. You should always discuss any such changes with your care team/GP before making big alterations to lifestyle.

As with all our blogs and other work we’d love to hear your thoughts and feedback, so feel free to comment below, drop me an e-mail at or tweet us/me at @XPERTHealth or @SWheatley88.

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