Ahhh, the keto diet.
With an army of advocates promising effortless weight loss, all-day energy and an end to hunger cravings… there’s no surprise that going keto is the hottest dietary trend right now.
The ketogenic diet (‘keto’ for short) is an eating plan that involves eating very few carbohydrates… and a lot of fat. It’s the reason people are putting butter in their coffee to lose weight, and ditching their morning oatmeal and blueberries for the much healthier option of fried eggs and bacon.
Sounds logical, right?
Although it may be new to many of us, the ketogenic diet actually dates back to the 1920s when scientists began to investigate it as a therapy for epilepsy. In the 60s and 70s carb cutting began to hit the mainstream media when it was first advertised as a weight loss aide, before it surged to popularity in the 90s thanks to diets like Atkins and South Beach.
If you’re spotting a pattern, that’s because low carb diets have been in and out of fashion for decades. The keto diet is simply the latest re-brand, and we’ve fallen for it yet again.
What exactly is ketosis?
To understand ketosis we must first understand how we make energy.
The human body’s preferred energy source is glucose, which we get from the consumption of carbohydrates such as fruit, vegetables and whole grains. Glucose is used as the primary fuel for the cells in our muscles and vital organs. The brain, for example, requires approximately 120 grams of glucose daily.
Interestingly though, our bodies cannot store much glucose. Which means if we do not consume carbohydrates for a few days, we must look for a secondary fuel source… otherwise we’d collapse and die.
Say hello to ketosis – a survival mechanism that our bodies adapted for when glucose wasn’t available – usually as a result of severe food scarcity.
When our body has no access to glucose, we begin to shift into a state of ketosis where our liver begins to break down fat into a usable energy source called ketones. Organs like the brain that normally run on glucose can begin to use these ketones for energy.
By switching to fat as a fuel source, our body immediately has access to thousands of calories stored as fat cells. It’s an amazing adaptation to starvation that allows vital organs like the brain survive for weeks without food.
In the modern day Western world, the vast majority of us are lucky enough to have never experienced a true state of starvation. However, more and more people are choosing to mimic the starvation response by ditching carbohydrates from their diet. When we deprive our bodies of glucose, our energy systems switch to the state of ketosis to keep us alive.
But just because ketosis is possible, doesn’t necessarily mean it is optimal…
Your body in ketosis
To get into ketosis, we must keep our carbohydrate intake extremely low. I’m talking a maximum of 5% of our total calories.
In order to do this we must immediately eliminate all foods containing high or moderate levels of carbohydrate. This means that cakes, sweets, bread and cookies are off the menu… but it also rules out fruit, potatoes, whole grains and legumes, and even has us limiting our consumption of most vegetables.
It’s at this point that the alarm bells start ringing.
It doesn’t take a scientist to know that fruits, vegetables, grains and legumes are some of the healthiest foods on the planet. By avoiding them entirely we put ourselves at a serious risk of vitamin and mineral deficiencies, and also leave our bodies deprived of important antioxidants and fibre.
This is because we benefit from a wide range of the antioxidants which promote cellular repair, and the diversity of soluble and insoluble fibres that help support a healthy gut microbiome.
More research is emerging than ever before about the importance of consuming a wide range of plant fibres in order to allow the good bacteria in our guts to thrive. A keto diet typically lacks the plant diversity needed to promote a healthy microbiome, thus compromising our digestive system and our ability to absorb all the nutrients from the food we eat.
And it isn’t just the foods that are missing on a keto diet… it’s the foods people are replacing them with.
Keto dieters typically recommend consuming high amounts of foods rich in saturated fat; such as butter, cheese and red meat. This is despite the fact that there is over 50 years of research showing links between these foods and an increased risk of heart disease and colon cancer⁴; and that every leading health organisation in the world actively recommends minimising our saturated fat consumption.
This is one of the main reasons why all of the world’s leading health experts are concerned about people on a keto diet, often calling it a “cardiologist’s nightmare.” At the European Society of Cardiology Congress in 2018, a 25,000 person study was presented that showed that people on the lowest carb diets had the highest risk of dying from cardiovascular disease and cancer and the lowest overall life expectancy. Another study from the same year published in the Lancet showed a higher risk of early death in people who followed diets that were low in carbohydrates and high in animal proteins, compared to those who consumed carbs in moderation.
Ketosis and longevity
Just because our body has the ability to enter ketosis does not make it optimal for our overall health and longevity. In fact, evidence shows it to be quite the opposite.
When we look at human evolution and traditional hunter-gatherer tribes, it would be common to enter a state of ketosis during winter, when carbohydrates such as fruit and starchy tubers would not be readily available. During these times I have no doubt that ketosis would have been a useful (and potentially lifesaving) adaptation.
But after the winter the summer always came – and with it an abundance of fresh produce. As soon as we could get out of ketosis and back to our bodies’ preferred fuel source of glucose, we did so. Looking back through human history there is no evidence of traditional societies voluntarily entering a state of ketosis at any time.
And in today’s world, all we need to do is look at the world’s healthiest and longest living populations (also known as the Blue Zones) to spot a clear pattern.
Residents of Blue Zones eat a predominantly plant based diet with the majority of calories coming from carbohydrates. The perfect example of this is Okinawa, Japan, where approximately 85% of their caloric intake comes from carbohydrates such as purple sweet potato, fruit and rice. Okinawa has the highest concentration of centenarians (people living to over 100 years old) anywhere on the planet.
If the apocalypse hit or our global food supply was wiped out by disease, I’d be extremely grateful for my body’s ability to enter ketosis. But when given the choice, I’d choose to eat an abundance of fresh fruits and vegetables every day of the week.
Are there any benefits?
Advocates of the keto diet tout improved brain function, effortless weight loss and reduced appetite as the main benefits of entering ketosis. Interestingly, these are some of the main benefits I also experience when following a whole foods plant based diet!
There is no reliable evidence that shows a ketogenic diet to be superior when it comes to brain function. When we look at it from an anthropological standpoint it doesn’t make sense, as ketones are our emergency fuel source that we use to keep the brain alive. Whenever glucose is available our body immediately switches back to it as a preferential fuel source.
One of the key components for a healthy brain are antioxidants, which are found in highest concentrations in plant foods. Following a whole foods plant based diet means eating an abundance of fresh fruits and vegetables every day, providing our brain with a flood of powerful antioxidants which reduce inflammation and decrease cellular aging. Plant foods also provide excellent sources of key minerals such as zinc and magnesium which play a key role in healthy brain function.
A ketogenic diet typically means low volume, high calorie foods such as meats, cheese, oils and nuts. Eating less volume of produce AND less variety of food makes it impossible to achieve the same micronutrient diversity of a whole foods plant based diet.
There’s also little evidence showing that a ketogenic diet works as an aid to weight loss any better than any other diet. It is theorised that the weight loss benefits experienced from a keto diet are simply a result of the subject falling into a caloric deficit, because it is hard to eat enough calories from fat to equal the calories they are burning. This is the same mechanism for weight loss that results from any other form of caloric restriction.
And as for the appetite suppression? Try eating a bowl full of black beans and broccoli and tell me you’re still hungry. Plant foods are packed with fibre which helps us feel fuller for longer, whilst also packing in a ton of nutrients (which keep us further satiated) for very few calories.
What about vegan keto?
Whilst I have no doubt that a vegan ketogenic diet is far better than an animal based one, it is still not something I recommend. The main reason being that the variety of food available is so limited you’d be putting yourself at a much greater risk of nutrient deficiency. You would be missing out on so many of the world’s healthiest foods such as fruit, sweet potatoes, whole grains, beans and lentils. And of course, there is absolutely no need to avoid or even restrict carbohydrates when they are eaten from healthy, whole food sources.
What’s more, eating the required fat to carbohydrate ratio on a vegan diet would be extremely difficult. Even an avocado, for instance, provides around 12g of carbohydrates. To reach a true state of ketosis you would likely have to consume additional fats through oils, which is not the way we are designed to consume dietary fat. Wherever possible your fats should always come from whole food plant based sources, where they come packaged with fibre and nutrients such as vitamin E which help our bodies to process them properly.
And then of course, there’s the practicality. With such a limited range of foods available, eating out at restaurants or at social occasions becomes a significant challenge. I believe that enjoying food with friends or loved ones is often just as important as the food itself, and there is absolutely no need to deprive yourself of this pleasure when eating a whole foods plant based diet.
Unless you have a medical reason for doing so, there is no need to embark on a ketogenic diet. By far the best way to improve your health and longevity is to follow a whole foods plant based diet with foods coming from all of the 6 major food groups. For weight loss simply adjust your caloric intake into a slight caloric deficit; so you can burn fat, remain energised and satiated, and still give your body all the micronutrients it needs.