Every creature that roams this planet consumes energy. And when we observe animals in their natural habitats it is obvious what they have evolved to eat. Lions eat antelope. Antelope eat grass. Bats eat insects. Koala bears eat eucalyptus leaves. And so on. Why is it then that when it comes to the optimal human diet we are so confused and conflicted. Are we carnivores, herbivores, frugivores, insectivores, or maybe omnivores? One moment you will hear that a healthy diet is a balanced diet. Then in the next moment, you might be watching a documentary like What the Health and hear that eating eggs are as bad as smoking. It is no wonder that so many people are bewildered by the array of conflicting advice being hurled at them every day by the media, medical professionals and that weird guy at the gym. To make sense of it all we must take a careful look at our evolutionary history, the controversies in nutrition science, the ethical dilemmas surrounding our dietary choices, the advice of medical professionals, and the lived experience of average people.
Let us now take a walk through our evolutionary history. We split from our most closely related cousin, the chimpanzee, about eight million years ago. However, our ancestors didn’t really come down from the trees until about four million years ago. During this time climatic changes led to a recession in the central African forests our ancient ancestors lived in, and increased open spaces and grasslands. This would also have been around the same time that meat began to appear in our diet. These early ancestors of ours likely ate a varied diet including grubs, fibrous tubers, nuts and seeds, and scavenged meat.
As our pre-sapien ancestors continued to move away from the trees, their brains kept getting bigger. Since brains are massive energy hogs we had to make some evolutionary cuts. The main place this was done was in the gut.
When you behold an image of a gorilla, orangutan or, to a lesser degree, chimpanzee your gaze may be drawn to their enormous bellies. This is because these cousins of ours are largely herbivorous. In order to digest all of the fibrous plant material they consume they have long large intestines and a big cecum (that’s the appendix in humans). These organs contain microbes that ferment the fiber in their diets and turn it into a digestible energy source. This is called hind gut digestion. Humans, by comparison, have larger small intestines and small large intestines – a digestive setup ideal for high-quality, high-calorie foods. Where might our ancestors have been getting their hands on calorie dense foods while roaming the African savannah? The answer is animals. Grasslands attract more large herbivores and mega-fauna than any other biome. So while there weren’t a lot of fruits and veggies to munch on, there was plenty of meat. The meaty diet of our ancestors is also reflected in the pH of our stomachs. An acidic stomach is needed for omnivorous and carnivorous diets in order to kill pathogens and parasites, and humans have a stomach pH that is comparable to dogs, wolves, bears and other omnivores.
Catching meat would have been difficult and it is likely that, before we developed advanced tool use and our outstanding endurance (more on that in a minute), we depended on larger predators to make kills for us. Then once these top dogs ate their fill we would have come in and used our big brains to smash open the bones and skulls with rocks to access the fat rich marrow and brain tissue left behind.
But to become the tall, upright-standing geniuses we are today we would need to become active hunters. This is where the ability to run comes into play. We (Homo sapiens) have an extremely energy efficient stride compared to our four-legged competition. We also sweat copiously, which is an extremely effective way of regulating body temperature, and we have hands with which we can carry water. These factors all combine to make humans endurance runners who are practically unrivaled in the animal kingdom. So, one of the leading theories as to how early man caught prey is that we would literally chase an animal until it collapsed from exhaustion. There are some tribes in Africa that still practice this persistence hunting. We also obviously developed hunting technology, like throwing spears, later on (because people are lazy).
Historically people have survived generational periods when they would have needed to eat hypercarnivorous, high fat diets to survive; think ice age Eurasia. Even today Inuit people living in more traditional ways survive almost exclusively off of animals products, with very low rates of heart disease to boot. So clearly, humans are capable of eating fat and meat. We are, after all, opportunistic feeders, able to eat almost anything, but meat has very obviously played an important role in our recent evolutionary history.
Now let us take a look at modern diets. There’s vegan, paleo, vegetarian, and the one we will be focusing on, a ketogenic diet. A ketogenic diet is one where the dieter gets a very high proportion of their energy from fats as opposed to carbohydrates. This is essentially the traditional Inuit diet of whale blubber and fatty fish. But in more recent, and well studied, history ketogenic diets were used on people who suffered from severe epileptic seizures.
It has been observed for a very long time that fasting is a great way to treat many illnesses. Fasting has been used to treat epilepsy since at least 500 B.C. In 1911 starvation was used by a pair of Parisian physicians to treat epilepsy in children and adults. During starvation, seizures were less severe. In the early 1920s it was noted by a Dr. Lennox at Harvard medical school that relief from seizures usually occurred two to three days into a fast.
However, starving yourself is obviously not a permanent solution. In 1921 it was observed that fasting produced ketones, our bodies alternative fuel to glucose. It was subsequently proposed by a Dr. Wilder that one could elevate ketones (hence ketogenic diet) in the body by eating a very high fat, low carb diet. The theory was tested and found to be astoundingly effective. It was reported that more than 50 per cent of children put on the diet managed to completely control their seizures, and another 27 per cent had partial improvement. Another surprising benefit was improvements in behaviour and cognition. Keto has now been successfully used to treat children with epilepsy for a century.
Despite the proven efficacy of the ketogenic diet in treating epilepsy, into the picture walked a man named Ancel Keys. In Nina Teicholz’s book The Big Fat Surprise she describes how Keys came onto the scene at a time when middle-aged men were dropping dead from heart disease, and no one knew why. Based on some rather flawed science Keys proposed his diet-heart hypothesis. The idea was that saturated fat caused heart disease by raising serum cholesterol levels. But his whole hypothesis was based on a study he performed called the seven countries study. In this study he cherry-picked countries that would support his hypothesis, all the while excluding countries like France – where people consume very high amounts of saturated fat but there are very few deaths from heart disease. Keys was an extremely charismatic person who was a very strong advocate of his theory and beat down competing ideas.
There were other studies done, such as the Minnesota Coronary experiment (MCE), in an attempt to prove the diet-heart hypothesis. The MCE was a double blind randomized control trial (considered the gold standard in scientific research) that took place in a nursing home and six state mental hospitals. The idea was to reduce the risk of death from coronary heart disease by lowering patient’s serum cholesterol with a diet rich in vegetable oils as opposed to saturated fat. When the study was published it was considered a success. However, the evidence is far from conclusive and actually seems to indicate the opposite of the diet-heart hypothesis is true. While the group given vegetable oil did have significantly lower serum cholesterol there was no significant reduction in the risk of death from coronary heart disease. In fact, there was an increase in all-cause mortality in those with lower serum cholesterol. So even if lowering cholesterol does decrease one’s risk for heart disease, which seems uncertain considering the body of evidence, is it worth it if lowering your cholesterol just increases your chances of cancer, stroke or some other fatal blow?
Other studies have been reevaluated in recent decades, such as the Sydney Diet Heart Study or the Nurses Health Study, that have either been inconclusive or found that lowering saturated fat increased all-cause mortality. There have also been a number of meta-analyses (looking at all the available data) and new studies that have indicated that perhaps lowering carbohydrates is a more effective method of reducing heart disease. Yet, Keys’ influence was so strong that nutrition science has been plagued by dogma for decades since his work. Today there are still people advocating low-fat diets as ideal for heart health.
Despite its long history, the ketogenic diet has been repeatedly smeared as a fad diet. While it has certainly gotten more media attention in the last few years it definitely isn’t new, and people have been having success with it for a long time. Many people come to the diet now with the hopes of weight loss or controlling their diabetes.
“I knew I was overweight and going in the wrong direction,” said Sue Helinga, a Guelph resident who went on the ketogenic diet for several months after a number of people she knew experienced success with it. “It was just a few pounds a year, y’know? But I knew I was headed in the wrong direction. I needed a jolt. A change. And I had a few other health concerns. Kind of pre-diabetic and my brother had just been diagnosed with diabetes. So there were just a few things that made me think ‘I better turn this boat around.’”
Helinga had quite a bit of success with the diet, losing a substantial amount of weight. But that wasn’t the only benefit she experienced. Many people report a clarity of mind and steady energy levels when in ketosis (the state when your body is fueling itself with ketones).
“Clarity of mind came,” said Helinga. “Kind of like the fog lifted a little bit … In that period of time when I was losing weight, I definitely had the clarity thing happening.”
While many people choose to undertake the ketogenic diet all on their own, Helinga did it through a program where she used foods provided for her.
“I don’t mind eating the same thing every day,” said Helinga. “I find my favourite foods, and would just rather eat my favourite foods every day than have a variety.”
While it is possible, with careful supplementation, to eat a vegan ketogenic diet, most people will be consuming some meat, as well as butter and cheese. This presents an ethical dilemma for people who are concerned about the treatment of animals and the environment.
“You read a lot about the environmental impact of eating animals,” said Helinga. “…. I’m kind of being pulled by the environmental issue. So, on the one hand, I would recommend it for weight loss. On the other hand … I don’t know it’s hard to know what the best thing is.”
Dr. Danilo Vitale, a chiropractor in Guelph, Ont., said, “So I have some concerns about confined area feedlots. We try to source most of our meat from local farms. They’re grass fed and grass finished … But it is a challenge.”
Vitale says he has always been interested in nutrition. “I’m a bit of an experimenter. n=1 is a term that is often used when you are your own subject. I’ve done blood work over years, and tracked my sleep, and self-experimented with different things.”
When asked how he approaches diet with his patients Vitale had this to say:
“We contrast what the standard North American diet is, which I would consider a high carb, highly processed, highly industrialized diet which, if you follow, you’ll end up with a lot of chronic health issues. So we contrast that with eating less carbs and talking about how eating less carbohydrates can reduce your inflammation and blood sugars … So I don’t tell people they have to do the ketogenic diet, but I encourage them to start reducing their carbohydrate intake, and seeing how they feel.”
One negative often leveled at the ketogenic diet is that it reflects poorly in strength and explosivity in relation to athletic performance. Vitale is himself an impressive athlete, having completed multiple ironmans, half ironmans, marathons and more. While these are endurance sports, not strength sports, he does have experience with more explosive training as well.
“I slowly shifted out of endurance sport into strength training, gymnastics, a lot of creative movements,” said Vitale. “Now I do CrossFit three to five days a week, and I’ve been doing that for almost five years. I’ve never noticed any losses in my strength. What I did notice was the really high-intensity work (was more difficult). And the jury is out on that research, it is coming down the pipeline now. Endurance athletes definitely will benefit (from keto).”
Intermittent fasting is often paired with a ketogenic diet. This is when one eats within a narrow window of a few hours every day.
“I think fasting is something we were evolutionarily designed for,” said Vitale. “We never had these three square meals until the agricultural revolution when we had access to all this food. The reality was, we would eat a lot of food and then we didn’t eat a lot of food. So our bodies are very, very well designed for when there is no food.”
Another individual with experience on the keto diet is Mary Gilbert of Guelph, who got into keto as a way to eat healthier and maintain weight loss, and has been eating that way for about a year.
“I think I’m one of the few people out there who didn’t start keto to lose weight,” Gilbert said. “I did that (lost weight) using extreme calorie restriction, which works but you’re miserable and you’re starving. So I stumbled across a low carb high fat diet through a nutritionist I know, and through that, it sort of evolved into keto naturally. And I’ve been doing that ever since.”
When asked if she had tried other diets Gilbert said she had grown up with very little awareness of diet plans. “I think this whole new way of thinking has kind of developed. The older generations kind of missed out on that. We were all thrilled to have processed foods.”
While Gilbert was unable to convince the rest of her family to eat keto she did say that her husband has lost weight just by virtue of eating her cooking, which now contains far fewer carbohydrates. “Which makes me mad because I have to work for every pound,” she added, laughing.
Gilbert stressed the benefit that the diet has on her energy levels. “I go to the gym five days a week, and I’m doing a blend of high-intensity interval training, cardio training, a lot of strength training, yoga, spin. So I’m able to do that one to two hours a day. And most of the time I’m doing that fasted.”
Despite all of the success stories, there are still people who believe that a ketogenic diet will kill an individual in the long run.
“It’s impossible not to think about it,” said Gilbert. “… It’s often the first thing people say is that ‘you’re eating so much fat. You’re going to clog your arteries!’ Well, dietary fat does not clog your arteries.
“For me, what I do is research. I spend hours and hours finding people in the world who know more about this than I do.”
The world is full of misinformation and poor research. However, it is abundantly clear that fat has been a part of the human diet for millions of years.
Further research on the ketogenic diet is needed. In the meantime, we should consider what the evidence is indicating. Evolutionary evidence shows a preponderance of animal fats and protein in our recent history. And recent evidence shows average people are experiencing astounding health benefits with ketogenic diets.
With more medical professionals coming out in support of high-fat diets, the keto diet is worth a try.