Paleo diet and ketosis

The Paleo diet can be ketogenic,
but only if you limit your carbs below 50 g a day

The Paleo diet is lower in carbs (less than 100 g a day for most people, but up to 150 g a day for active people) compared to the standard American diet (an average of 300 g a day!).

Ketosis Vs. Ketoacidosis

Many people, including doctors, dietitians and health professionals, confuse ketosis with ketoacidosis and advise against low-carb diets because of this. If you eat a low-carb diet (which could be defined as providing less than 50 g of carbs a day), you will likely be in ketosis. In other words, it means that your body will be primarily utilizing fat (both the fat you eat and the fat you have stored on your body) and ketones (a by-product of fat oxidation) for energy.

Ketosis as the result of a low-carb diet is also referred to as nutritional ketosis. Ketosis is not dangerous and simply means that the levels of ketones in your body are slightly higher (between 3 and 5 mM vs. 0.5 mM with a high-carb diet) compared to a sugar burner because your body has become a fat burner. (5)

Ketoacidosis, on the other hand, is a medical emergency and occurs when ketone levels rise 5 to 10-fold higher compared to nutritional ketosis (between 15 and 25 mM). Ketoacidosis can only happen in the almost complete absence of insulin, such as in uncontrolled type 1 diabetes. (5)

Ketone levels vary depending on your carb intake

Type of diet

Ketone levels*

High-carb diet (standard American diet)

less than 0.5 mM

Paleo diet (unless restricting carbs < 50 g/d)

0.5-3 mM

Ketosis (very low-carb diet; < 50 g a day)

3-5 mM

Ketoacidosis (diabetic medical emergency)

15-25 mM

* (5)

Side effects during the transition to a
lower-carb diet
(keto-adaptation or fat-adaptation)

Whether you adopt a ketogenic version of the Paleo diet or not, decreasing your carb intake by ditching grains and sugar requires your body to go through an adaptation period called keto-adaptation (or fat-adaptation). This transition usually lasts 1-2 weeks, although it can take as long as 4 weeks in some people. After decreasing your carb intake, you may experience some transient side effects, such as fatigue, irritability, dizziness (especially upon standing), headaches, weakness, sugar or carb cravings and constipation. (5)

The main reasons why you experience these symptoms when transitioning to a lower carb / Paleo diet can be due to:

  1. the transition of your brain and body from using glucose/carbohydrates for energy to utilizing more fat and ketone bodies (keto-adaptation);

  2. the diuretic effect of lower carb diets which can lead to mild dehydration; and/or

  3. the withdrawal symptoms associated with the removal of addictive substances, such as grains (gluten), dairy (casein) and sugar, from your diet.
You can ease the transition to your Paleo diet, minimize side effects and promote a faster keto-adaptation by:
  • eating plenty of fat: include avocado, coconut oil, olive oil, lard, ghee, chicken skin, bacon and/or fatty cuts of meats at each meal;

  • drinking a lot of fluid: aim for at least 2L a day, ideally from water, tea or homemade bone broth;

  • supplementing your diet with a touch of salt: try homemade bone broth or sprinkle ½ tsp of Celtic salt, Himalayan salt or other mineral-rich salt over your food every day; and

  • taking it easy with your physical activity: decrease the intensity/duration of your exercise until your body becomes keto-adapted.
Special considerations

Always check with your doctor first before making any changes to your diet, especially if you decide to adopt a ketogenic diet.

If you have blood sugar issues, diabetes, hypertension or any other medical conditions and/or take prescribed medications, consult your doctor or registered dietitian for help during the transition to a lower carb diet. Decreasing your carb intake can rapidly lower your blood sugar levels, blood pressure and other health parameters, which may require prompt adjustments to your medications or medical treatment.

★ If your doctor is not familiar with low-carb / Paleo diets,
consult the Paleo Physician Network, PrimalDocs 
or Jimmy Moore’s list of Low-Carb Doctors.

Learn more with the Paleo dietitian:
Learn more about carbohydrates on the Paleo diet
Determine your personal carb target on the Paleo diet
Read about how your brain can function with a lower carb intake.

Sign up for the Paleo dietitian's newsletter below:

Enter your E-mail Address
Enter your First Name (optional)

Don't worry — your e-mail address is totally secure.
I promise to use it only to send you the Paleo RD Newsletter.

References:(1) Cordain L, et al. Origins and evolution of the Western diet: health implications for the 21st century. Am J Clin Nutr. 2005; 81: 341-54.(2) Cordain L, et al. Hyperinsulinemic Diseases of Civilization: More Than Just Syndrome X. Comparative Biochemistry and Physiology Part A. 2003; 136: 95–112.(3) Nutrition & Metabolism Society. Top Ten Low Carb Myths. Nutriton & Metabolism Society website.(4) Hite AH, et al. Low-Carbohydrate Diet Review: Shifting the Paradigm. Nutr Clin Pract. 2011; 26: 300-308.(5) Phinney SD and Volek JS. The Art and Science of Low Carbohydrate Living: An Expert Guide to Making the Life-Saving Benefits of Carbohydrate Restriction Sustainable and Enjoyable. 2011.(6) Food and Nutrition Board of the Institute of Medicine. Dietary Reference Intakes for Energy, Carbohydrate, Fiber, Fat, Fatty Acids, Cholesterol, Protein, and Amino Acids (Macronutrients). The National Academies Press. 2005: 275.(7) Taubes G. Good Calories, Bad Calories: Fats, Carbs, and the Controversial Science of Diet and Health. 2008.(8) Sokoloff L. Metabolism of Ketone Bodies by the Brain. Annu Rev Med. 1973; 24: 271-80.(9) Veech RL. The Therapeutic Implications of Ketone Bodies: The Effects of Ketone Bodies in Pathological Conditions: Ketosis, Ketogenic Diet, Redox States, Insulin Resistance, and Mitochondrial Metabolism. Prostaglandins, Leukotrienes and Essential Fatty Acids. 2004; 70: 309–319.(10) Veech RL, et al. Ketone Bodies, Potential Therapeutic Uses. IUBMB Life. 2001; 51: 241–247.

New! Comments

Have your say about what you just read! Leave me a comment in the box below.

read my disclaimer.

Ready to take the REAL food challenge?
join the next REAL food challenge!

The Paleo Diet Budget Shopping Guide