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  • Writer's pictureLisa Wartenberg, RD, LD

What is the Keto Diet anyway?

Between the 5:2, peganism, the celery juice detox, Whole 30, the flexitarian diet, the alkaline, the Wolf diet - who can keep up with all these fads? Have no fear, dear readers, Science to the Table is here.

Although this diet has been around for a while, I get asked about the Keto Diet quite a lot. What gives?

Well, before we really dig into the Ketogenic Diet (KD), let’s walk it back a bit and first examine our body’s metabolism. If you’ll think back to your days of middle school biology class, you’ll remember that our body breaks down food for energy, with carbohydrates (glucose) as the preferred energy source, and metabolizes proteins and fats for rebuilding and energy stores, respectively.2 As a survival mechanism, our body can also break down fat when it doesn't have carbs available. Thus, the underlying concept of a Ketogenic Diet is to create these conditions, thereby forcing the body to break down fat as an energy substrate, instead of glucose, by depleting it of carbs. In other words, eliminating dietary carbs increases fatty acids and ketones.3

If this sounds extreme, that’s because it can be. That is, the Ketogenic Diet is traditionally a therapeutic diet primarily reserved for children with intractable epilepsy, as first proposed by Dr. R.M. Wilder at the Mayo Clinic in 1921.1 There's two prominent theories centering on this connection of the brain, the Keto Diet, and epilepsy. Researchers believe that this mechanism functions on either the depletion of glucose or the increased circulation of ketones having a brain-protecting effect, which can reduce epileptic seizures (though recently, more evidence seems to support the latter theory).3

Types of Ketogenic Diets

Clinical KD. This is designed as medical nutrition therapy and can only work under strict medical supervision, as described above. For these patients, inpatient clinical supervision is a must, at least during the transitional period in which the body adjusts to its new energy substrate as a result of the depletion forcing the body into ketosis.3 This a critical period; as the body fights to maintain its current system of breaking down carbohydrates for energy, even trace amounts of carbohydrates can actually exacerbate epileptic episodes. Additionally, ketogenic diets are being increasingly utilized alongside cancer therapy.1 It is thought to increase responsiveness to chemotherapy as well as slow tumor growth in certain cancers of the brain, though more clinical research is needed in this area.1

Modified KD. As a short-term approach to curbing insulin resistance associated with obesity, a modified KD may be a beneficial weight-loss catalyst. However, because it may lack the full array of vitamins, minerals, antioxidants, and other beneficial substances found in diets that include more fruits and vegetables, it may prove counterproductive as a long-term lifestyle. Why? Because diets don't work - at least not in the long run. But more on that soon.

Ratios. This is an important word when it comes to the world of Ketogenic Diets. In a strict, medically-supervised Classical KD, a ratio of 4:1 is often observed. This means that the diet consists of 4 parts fat to 1 part protein+carbs combined, as measured in total percentage of calories. In other words, only 20% of calories would come from a combination of carbs and protein, while the other 80% of calories would come from fat. More liberalized, popularized versions of the KD might have ratios as liberal as 1:1, meaning that 50% of calories come from fat, while the other 50% come from a combination of protein and carbs. Some even supplement their fat intake with MCT Oil (medium-chain triglyceride oil), as this is metabolized differently than other fats and has higher ketogenic potential.4,5


What does a Keto Diet look like?

High fat, moderate protein, and low carbs. That's the basic formula.


Is it right for me?

This sounds like a conversation between you and your doctor or Registered Dietitian (RD). As mentioned, the Keto Diet has its roots as medical nutrition therapy, but some people feel its modified versions may be useful as a weight loss tool. If you're considering adopting this diet, here are some questions you should ask yourself (before talking to your RD):

  • What happens after the Keto Diet?

  • What habits do you hope to gain from the KD?

  • What habits do you newly adopt when you're off KD?

However, shorter-term fixes may not ultimately be your best approach to weight loss. Stay tuned for more thoughts on that.

Note: Please talk to your doctor or Registered Dietitian before making changes to your diet or physical activity. Any mentions of diets or products here or anywhere on this site should not be taken as an endorsement, medical diagnosis, or medical advice.



  1. Allen BG, et al (2014). Ketogenic diets as an adjuvant cancer therapy: History and potential mechanism. Redox Biology 2; 963-970. doi:10.1016/j.redox.2014.08.002

  2. Da Poian A.T.,  El-Bacha T. & Luz, M. R.M.P. (2010). Nutrient Utilization in Humans: Metabolism Pathways. Nature Education 3(9):11

  3. Roehl K. & Sewak S.L. (2017). Classic and Modified Ketogenic Diets for Treatment of Epilepsy. J Acad Nutr Diet. 2017;117:1279-1292

  4. Gracey M., Burke B., Anderson C.M. (1970). Medium Chain Triglycerides in Paediatric Practice. Archives of Disease in Childhood 45:445-452. doi:10.1136/adc.45.242.445

  5. Branco A.F., Ferreira A., Simões R.F. et al. (2016). Ketogenic diets: from cancer to mitochondrial diseases and beyond. European Journal of Clinical Investigation. 46:3. doi:10.1111/eci.12591

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