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  • Writer's pictureRani

Unveiling the Truth: How the Keto Diet Impacts Blood Sugar Levels

Updated: Feb 24

The ketogenic (keto) diet has garnered attention for its alleged ability to reverse diabetes and blood sugar dysregulation. However, a closer look at the science behind blood sugar dysregulation challenges this claim. In this post, we'll delve into the misconception surrounding the keto diet and its impact on diabetes and blood sugar.

The Role of Blood Glucose:

Our bodies primarily rely on blood glucose (sugar) as a preferred fuel, especially for the brain. Insulin acts as the key that unlocks cells, allowing glucose to enter and be utilized for energy. Without insulin, blood sugar levels then rise, damaging vital organs in the process.

While keto claims the body can function on fat due to entering a ketosis state, there are associated costs, as discussed in my previous post on keto and weight loss.

Understanding Elevated Blood Sugar Levels Within the Body:

Diabetes mellitus is marked by elevated blood sugar levels, particularly in type 2 diabetes, where the body becomes resistant to insulin (1). Excessive sugar accumulation in the bloodstream can overwhelm the kidneys and spill into the urine, posing significant health risks. Even in the absence of a diabetes diagnosis, persistent high blood sugar can lead to inflammation, hormonal imbalances, and reproductive health issues, causing disruptions in normal bodily functions with a cascading effect on overall health.

Individuals with diabetes face nerve and artery damage due to an inflammatory metabolic toxin known as methylglyoxal, which forms at elevated blood sugar levels (2). Managing blood sugar levels is crucial in mitigating these risks.

High-Fat Diets and Their Effect on the Body:

Contrary to popular belief, high-fat diets, such as the Atkins diet (high fat/low carb), can exacerbate the situation (2). After just a few weeks on the Atkins diet, there was a notable increase in methylglyoxal levels. Those in active ketosis experienced a doubling of glycotoxin levels in their bloodstream. In essence, high-fat diets contribute to the formation of metabolic toxins in the bloodstream, paralleling the impact of high sugar levels, with ketosis exacerbating the situation.

The Reality of High Fat Diets and Blood Sugar Levels:

Ketogenic diets claiming to "reverse" diabetes often blur the distinction between symptoms (high blood sugars) and disease—carbohydrate intolerance. Individuals with diabetes face challenges processing carbohydrates efficiently, leading to elevated blood sugar levels. Despite the perception that a high-fat diet maintains low blood sugars, it may inadvertently worsen the underlying disease. Historical evidence spanning nearly a century indicates that a ketogenic diet can lead to a rapid escalation of carbohydrate intolerance, as demonstrated in the graph below.

Graph depicting the spike in carbohydrate intolerance within just two days on a ketogenic diet (3).

Graph from: Sweeney JS. Dietary factors that influence the dextrose tolerance test. JAMA. 1927;40(6):818-830.

Moreover, consuming an 80% fat diet for a week may quintuple blood sugar spikes (shown in the graph below) in response to the same carbohydrate load, compared to a low-fat diet (4).

Graph from: Himsworth HP. Dietetic factors influencing the glucose tolerance and the activity of insulin. J Physiol (Lond). 1934;81(1):29-48.

For individuals undergoing diabetes tests, the choice of a fatty dinner the night before can adversely impact the results (5). A single meal high in saturated fat can exacerbate the root cause of diabetes—carbohydrate intolerance—within a mere four hours (5). Essentially, a high-fat diet acts as fuel on the fire, concurrently treating symptoms while intensifying the underlying disease.

Debunking the Notion of Diabetes Reversal through Keto:

The claim that keto can "reverse" diabetes hinges on successfully weaning individuals off insulin. However, eliminating carbohydrates does not eradicate carbohydrate intolerance, as evidenced by the persistent blood sugar spike when carbs are reintroduced. It's like fake healing yourself—addressing the symptom while leaving the disease untreated.

True Diabetes Reversal:

Contrary to the keto approach, a genuine diabetes reversal diet involves consuming over 300 grams of carbs daily (6). Research indicates that adopting a healthy, high-carb, low-fat diet can lead to insulin normalization and authentic diabetes reversal.

Showing that being on 314 g/day of carbs resulted in being able to come off insulin medication (6).

In summary, the keto diet might help with blood sugar levels, but it doesn't tackle the main issue of high blood sugar. A holistic approach, emphasizing carbohydrate tolerance and a balanced diet (high carb, low fat), is more effective in truly reversing diabetes. Managing blood sugar levels while addressing the root causes is essential to avoid unintentionally worsening overall health.

Other posts that are relevant to this topic:


  1. Greger, M., & Stone, G. (2018). How not to die: Discover the foods scientifically proven to prevent and reverse disease. Pan Books.

  2. Beisswenger BG, Delucia EM, Lapoint N, Sanford RJ, Beisswenger PJ. Ketosis leads to increased methylglyoxal production on the Atkins diet. Ann N Y Acad Sci. 2005;1043:201-10.

  3. Sweeney JS. Dietary factors that influence the dextrose tolerance test. JAMA. 1927;40(6):818-830.

  4. Himsworth HP. Dietetic factors influencing the glucose tolerance and the activity of insulin. J Physiol (Lond). 1934;81(1):29-48.

  5. Robertson MD, Henderson RA, Vist GE, Rumsey RD. Extended effects of evening meal carbohydrate-to-fat ratio on fasting and postprandial substrate metabolism. Am J Clin Nutr. 2002;75(3):505-10.

  6. Anderson JW, Ward K. High-carbohydrate, high-fiber diets for insulin-treated men with diabetes mellitus. Am J Clin Nutr. 1979;32(11):2312-21.



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