Complementary Medicine/Articles

 Understanding Ketones and Low Carbohydrate Diets

 A common misunderstanding regarding the metabolic effects of low carb diets is the formation of ketone bodies. The presence of ketones is often confused with ketoacidosis resulting from uncontrolled diabetes, starvation or certain alcoholic conditions.

Dietary ketones are more common that most people realize. In addition to a low carb intake, they occur on any weight loss plan when fat is burned or even after an overnight fast.

 Ketones and Evolution

Ketones are produced when fat is utilized to meet energy needs as occurs when the diet comprises less than about 50 grams of carbohydrates daily.  They are a source of energy for the heart muscle and a backup fuel source for the brain. It is because of our bodies’ ability to utilize stored fat in times of a limited food supply that man has survived. This ability to safely use ketones preserves lean body mass. 

Almost all body tissues can utilize ketones as fuel. Even on a low carb plan the body is still able to provide glucose to those cells that require it.

According to Dr. Richard Veech, an NIH researcher and expert on ketones, both the brain and heart work more efficiently on ketones than glucose. He also states that the fear of ketones is likely to be exaggerated.1

 Ketoacidosis or Dietary Ketones

Diabetic ketoacidosis inpeople with diabetes occurs when blood sugar levels are exceeding high because insulin levels are too low. The inability of the body to handle the high levels of glucose leads to a large production of acid compounds that the body is unable to neutralize. Dehydration occurs as the body loses large amounts of water through the urine attempting to remove excess glucose. This combination of circumstances leads to a life-threatening acidosis. To clarify the misconception and confusion among many (including the medical profession) one does not get acidosis simply from having ketones when controlling carbs.2


Compare the amount of ketones produced when burning fat to other states.

Blood levels of ketones:

Fed state---0.1mmol/L

Overnight fast---0.3mmol/L.

On low carb---1 to 2 mmol/L

More than 20 days fasting---10mmol/L

Diabetic ketoacidosis---more than 25mmol/L.


 Even a person with diabetes can safely utilize ketones if they are the result of a low carb plan. Additionally, because they are eating low carb their blood sugar levels are likely to be better controlled than when eating a diet of 55 to 60 percent carbs.3 Note that a low carb plan can significantly reduce the need for blood sugar medications. A person with diabetes should not change their diet without consulting their doctor.

Fat as FuelThe idea that one needs large amounts of carbs to aerobically exercise is incorrect. People on low carb diets are able to participate in exercise after allowing a period of adaptation. A number of studies have demonstrated better endurance in professional athletics when utilizing fat as fuel. 4

 What better way to use up those excess fat stores that can damage your health than to burn them for fuel? Return to the kind of dietary intake our bodies were designed for: proteins, natural fats and low glycemic whole carbohydrate foods. Add in regular physical activity and find the level of carbohydrate consumption that allows you to gradually and safely decrease those excess fat storage depots.


  1. Veech, R., Chance, Britton, et al, “Ketone Bodies, Potential Theraputic Uses”, IUBMB Life, 2001, 51: 241-247.
  2. Westman, E., Yancy, W., at al, “Effect of 6-Month Adherence to a Very Low      Carbohydrate Diet Program,” American Journal of Medicine, 2002, 113, 30-36.
  3.  Nielsen, J.V., Joensson, E., “Low-carbohydrate diet in type 2 diabetes. Stable improvement of body weight and glycaemic control during 22 months followup”, Nutrition & Metabolism, 2006, 3:22.
  4. Phinney, S. “Ketogenic diets and physical performance”, Nutrition & Metabolism, 2004, 1:2.

 This information is in no way intended as medical advice or as a substitute for medical treatment. This information should be used in conjunction with the guidance and care of your physician.