The keto diet

The keto diet is gaining popularity in the mainstream health conscious community. In fact, Google searches trends show that there has been a massive surge of interest in the past 1.5 years, particularly in the past 6 months.

Interestingly, while searches for “ketogenic diet” have remained fairly stable, searches for “keto diet” are on the rise (one has to wonder how many people don’t know that “keto” stands for “ketogenic).

As shown below, trends are similar in Australia.

What is a ketogenic diet?

Ketogenic diets were designed in the 1920s as therapeutic diets for the treatment of epilepsy. They are low in carbohydrate, moderate in protein and high in fat in order to generate ketones.

Ketones are simple compounds made of hydrogen, carbon, and oxygen made in the liver from fat. Ketosis is a metabolic state whereby the body generates most of its energy requirements from ketones rather than carbohydrate (1). This metabolic state has shown benefits in the treatment of epilepsy and other neurological conditions, metabolic syndrome, obesity, insulin resistance, type 2 diabetes, certain cancers and mitochondrial diseases (1, 2, 3, 4, 5).

Ketogenic diets are typically constructed with ratios ranging from 2:1 to 4:1 of fat to protein + carbohydrates. This means that at least 2/3 of the dietary energy will be coming from fats. To put this into numbers, let’s take an average dietary intake of 2000 kilocalories (Cals).

In the less strict version of the keto diet, the person would need to consume 148.1g of fat and 74.1g of carbohydrates and protein combined (1g fat = 9Cal, 1g protein/carbs = 4Cal). Let’s say this person weighs 60kg and wants to meet their dietary requirements by consuming 0.8g protein per kg of body weight, they would be consuming 48g of protein, leaving 26.1g of carbohydrate to consume per day. That’s not much, as you can see in the table below.

Keto these days

As the terms “keto” and “ketogenic” become more common in the media and everyday conversations, there is more uncertainty as to what is considered a keto diet. Low carbohydrate and high protein diets are not necessarily ketogenic, because availability of glucose from carbohydrate intake or gluconeogenesis (where excess protein is converted into glucose) will prevent the body from generating ketones.

There’s also a long record of tricking the body into producing ketones. Medium-chain triglycerides (MCT) oil has been used since the 1960s to facilitate this process allowing patients to be less restrictive with protein and carb intake (3). MCT oil has had a resurgence in the past few years thanks largely to Dave Asprey’s Bulletproof coffee.

Ketone supplements (a.k.a. “exogenous ketones”) are another tool that can help achieve ketosis without severe carbohydrate and protein restriction. They are sold as ketone salts and ketone esters and have been used in the military special forces and sport (1). I’d argue that adding exogenous ketones so that they are available for utilisation does not equal generating ketones, and thus a diet that relies on those products should not be considered ketogenic.

Moreover, I’d argue that unless you’re measuring your ketone levels (blood measurement is the most accurate way), you can’t be sure your diet is indeed ketogenic, particularly because different people will produce different levels of ketones at different levels of macronutrient intake. For an indication, it appears that blood levels must be greater than 5mmol/L for ketones to use be as preferential fuel source for the brain (1).

Cons of the keto diet

Documented potential negative side effects of ketogenic diets include:

• Short-term include gastro intestinal problems (5)
• Hyperlipidaemia, hypercholesterolaemia (2, 5)
• Kidney stones and possible kidney damage (2, 4)
• Electrolyte and/or calcium deficiencies due to increased excretion (1, 2)
• Gout (2)
• Risk of nutritional deficiencies (1)

In addition, following a ketogenic diet can be difficult, particularly for people who eat out and/or travel a lot. Food must be weighed, measured and logged to ensure compliance to the protocol. Ketones must be measured to ensure adequate levels are being produced. As an anecdote, I ate less than 30g of carbs per day on low-carb days while trialling the AltShift diet. Even though my usual diet is generally low-carb, I found it hard to stay below the carb limit.

Who is the keto diet right for?

If you have a health condition that has been shown to benefit from a ketogenic diet (see “What is a ketogenic diet?” section above), you may consider giving it a shot. Please check with your doctor and/or dietitian before jumping into it.

One last thing to consider with this and any other diets, is that food quality is more important than anything else. Yes, you can do keto by eating bacon 24/7 but you would likely develop nutritional deficiencies.

Vegan keto diet?

While in theory is possible to do vegan keto, a lot of vegan staples (fruits, some vegetables, grains and cereals, legumes) are high in carbohydrates. Also, a lot of keto staples (eggs, meat, fish, cheese, cream) are not vegan. It would be extremely hard to construct a nutritionally adequate vegan keto diet.

References

1. Scott, JM and Deuster, PA. Ketones and Human Performance. J Spec Oper Med. 2017;17(2):112-116.
2. A Review of Low-carbohydrate Ketogenic Diets. Westman, EC et al. Curr Atheroscler Rep. 2003;5:476.
3. Sinha, SR and Kossoff, EH. The ketogenic diet. Neurologist. 2015;11(3):161-170.
4. Paoli A, et al. Beyond weight loss: a review of the therapeutic uses of very-low-carbohydrate (ketogenic) diets. European Journal Of Clinical Nutrition. 2013;67:789.
5. Branco AF, et al. Ketogenic diets: from cancer to mitochondrial diseases and beyond. Eur J Clin Invest. 2016;46(3):285-98.

[Photo by Casey DeViese on Unsplash]

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