The latest trend in nutrition is the ketogenic diet. The defining principle of the ketogenic diet is that it severely restricts the intake of carbohydrates to less than 50 grams per day, ideally as low as 20 grams. For comparison, the average person consumes 265 grams per day. It also relies on consuming a very high percentage of fat per day, often at levels around 70 to 90 percent of the total daily caloric intake. The point is to trigger your body into burning fat and reaching a stage of ketosis. Yes, makes sense, and you can likely see where there would be health conditions in which fat burning would be favorable.
Although there might be undeniable promise and benefits to this diet for certain health conditions, there are also potential downsides to consider. Having downsides does not automatically dismiss the potential benefits of the diet. It simply means that this diet might not be for everyone all the time under every condition, and that we need to accommodate for these factors by working with a qualified health (functional medicine) practitioner who can help navigate this path.
Here are four areas for greater awareness:
Increased Exposure to Lipophilic Toxins
Unlike other low-carb diets, the ketogenic diet emphasizes the consumption of fat. However, we also need to note that many environmental toxins are lipophilic, which means they get stored in adipose tissue. Examples include:
- Persistent organic pollutants (POPs)
- Polychlorinated biphenyls (PCBs)
- Organochlorine (OC) pesticides
- Polybrominated flame retardants
- Polybrominated diphenyl ethers (PBDEs)
- Bisphenol-A (BPA)
When you consume food sources of fat contaminated with these toxins, you become exposed and increase your toxin load. In various populations, these toxins have been linked to an increased risk of developing various diseases, including stroke, cognitive disorders, blood sugar dysregulation, obesity, autoimmune disorders, and reproductive disorders.
To reduce toxic fats, choose foods with relatively lower toxin levels, such as organic cuts of meat, organic produce, and wild fish. However, note that just choosing organic foods doesn’t completely protect you from contaminants, but it’s a relatively better choice.
Risk of Metabolic Endotoxemia
Studies have shown a link between diets higher in fat and an increased risk of metabolic endotoxemia. Metabolic endotoxemia occurs with high amounts of lipopolysaccharides (LPS or endotoxin) in the blood due to an excess of gram-negative bacteria in the gut, otherwise known as dysbiosis. This increase of circulating endotoxin leads to low-grade systemic inflammation and associated chronic illnesses.
Although many of the studies demonstrating the connection between high-fat diets and metabolic endotoxins follow a pattern similar to a Western diet rather than a ketogenic diet, there have been studies demonstrating that high levels of healthy fats, such as coconut oil, might also contribute to metabolic endotoxemia.
The evidence is limited at the moment for a direct connection between a ketogenic diet and metabolic endotoxemia. One mouse study did show a potential ability of the ketogenic diet to reduce acute inflammation upon exposure to endotoxin, but it did not go into details about the impact of chronic consumption of high amounts of fat on the diet. More research needs to be conducted. However, it’s worthwhile to be thinking about healing the gut and ensuring a healthy microbiome before having consistently high levels of fat in the diet.
Along the same lines, a ketogenic diet generally incorporates less fiber, which could also negatively impact the microbiome and lead to dysbiosis. It is possible to reduce some of the inflammation and other issues through consuming prebiotic fiber, such as oligofructose-enriched inulin.
Dietary Fat Quality and Ratios
Another downside of the ketogenic diet is that some people believe it gives them free range to excessive amounts of any type of fat from any food source. As you know, different fats have different impacts on each body, and everyone responds uniquely, depending on what they are eating in the broader context, their biochemistry, genes, stress level, and gut microbiome profile, to name a few. Therefore, it is essential to look qualitatively at a ketogenic diet to examine the best sources of fat for the individual.
In general, fats such as monounsaturated fatty acids and polyunsaturated fatty acids, especially omega-3 fatty acids, have often been shown to have an inverse association with certain diseases, such as cardiovascular disease and metabolic disorders. Conversely, trans fat and saturated fat have been associated with a higher risk of these diseases, although this area remains the subject of ongoing debate.
My take is that it’s not so much about maligning a particular category of fat, like whether something is “polyunsaturated” or “saturated”. Rather, it’s largely about the dietary ratios between all these fats within the foods they occur in, their relative ratios in our blood and tissues, and what the other nutrient components are in the food source. Let me restate: no particular source of fat is truly “bad” – it’s about looking at the bigger picture of the food and the meal composition. That said, only focusing on the total quantity of fat for a ketogenic diet without paying attention to the quality of the fat source may potentially lead to issues like increased inflammation down the line, depending on health risk factors, genes, and environment.
Reduced Intake of Vegetables and Fruits
You know that I always talk about colorful food. That is the one research point in nutritional science that I can surely stand behind. And others are with me, as several other researchers and clinicians cannot argue with the benefits of consuming vegetables and fruit. Numerous studies demonstrate a decreased risk of chronic disease and mortality in those who consume more fruits and vegetables, thanks to their high levels of essential vitamins, minerals, antioxidants, and other phytochemicals. Studies have found that the health benefits rise with the more vegetables and fruits consumed.
However, fruits and vegetables also inherently have some amount of carbohydrates. When you consume a diet that is supposed to have only 25 to 50 grams of carbs per day, it becomes very difficult to consume the recommended 9 to 14 servings of fruits and vegetables per day. It is important to take care when creating your meal plans for this type of diet that you include quality fruits and vegetables as much as possible, especially those high in fiber, rich in nutrients, and lower in carbohydrates.
If you choose to embark on following a ketogenic diet, it is best to educate yourself as much as possible to determine the healthiest, best way to make sure it works for you. My preference is to have people consult with a trained health professional who can create a personalized plan.