The Ketogenic Diet - Yaletown Nutrition
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The Ketogenic Diet

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A little while ago we talked about carbohydrates on the blog, what they are and why they’re important for our health. So, what’s the deal with the ever-popular ketogenic, aka keto, diet that has people removing almost all carbohydrates from their diet, and why has it become so trendy? The keto diet claims to help people lose weight and reduce the risk of certain chronic diseases, such as heart disease, cancer, and diabetes, but are these claims backed by high quality evidence and what effects does this diet have on our overall well being?


What is the ketogenic diet?

The ketogenic diet has been around for quite some time. It was originally introduced in the 1920s as an effective treatment option for children with epilepsy. It was found that when the brain was fueled by ketones instead of glucose (sugar) seizure frequency decreased, although the mechanism for why this happens is still not fully understood.

In the last decade, this diet has gained a lot of popularity in the mainstream media and diet industry, and it doesn’t seem to be going away anytime soon. But is this concept of demonizing and restricting carbohydrates new? Definitely not. Low carb, high fat diets have been promoted for weight loss since the 1860s, if not longer. More recent low-carb fad diets include the South Beach Diet and the Atkins Diet. Is the ketogenic diet just another restrictive eating pattern presented in a different way?

The ketogenic diet is a very high fat, moderate protein, very low carbohydrate diet. The main goal of the keto diet is to put your body into nutritional ketosis, where the body uses ketones for energy instead of glucose. Glucose, a type of carbohydrate, is our bodies’ preferred source of fuel as it can be used for energy almost immediately. We get glucose by eating and breaking down carbohydrate-rich foods, like fruit, grains, starchy vegetables, and desserts. Ketones, on the other hand, are a by-product of breaking down fats. Ketones are produced when the body must use fat for energy because there aren’t enough carbs available. In other words, ketones are used as a back-up fuel source when there is not enough glucose available for energy, or when your body has entered a fasted or “starvation” period.

To enter ketosis, approximately 75-80% of a person’s calories should come from fats, with approximately 15-20% of calories coming from protein, and only 5% or less from carbohydrates. To compare, health experts recommend that a balanced and varied eating pattern provides about 20-35% of calories from fat, 10-35% from protein, and 45-65% of calories from carbohydrates. This balanced distribution allows for a much more flexible and varied eating pattern.


To truly achieve nutritional ketosis, a person must significantly restrict their carbohydrate intake, often to less than 20-35 grams of net carbohydrates per day. Net carbohydrates do not include fibre, which is also a type of carbohydrate, but fibre does not get digested and absorbed by the body, so it does not raise blood sugar levels. This means that pretty much all carbohydrate-rich foods need to be restricted to achieve ketosis. This includes restricting:

  • Grains and grain products: oats, rice, quinoa, millet, farro, orzo, couscous, bread, tortillas, cereals, pasta, noodles, chapati, naan, granola
  • Fruit: bananas, grapes, oranges, apples, melon, pears, peaches, kiwis, cherries, pineapple, mango
  • Dairy products: flavoured yogurts, milk, buttermilk
  • Starchy vegetables: potatoes, yams, squash, peas, parsnips, rutabagas, carrots
  • Legumes: beans, chickpeas, lentils, split peas
  • Certain nuts: cashews, pistachios
  • Desserts, chocolates, candies, and baked goods
  • Juices, sodas, sugar-sweetened beverages
  • Beer
  • Sweeteners: honey, maple syrup, agave syrup, sugar, coconut sugar
  • High-carb sauces: barbecue sauces, teriyaki sauces, ketchup, salad dressings


Instead, the ketogenic diet focuses on high-fat foods, with a moderate amount of protein. It is important that not too much protein is consumed as protein can also be turned into glucose if eaten in higher amounts. A well-planned, ketogenic diet will rely heavily on: 

  • High-fat dairy: cheese, cream, sour cream, whipped cream, butter, full fat milk, full fat plain yogurt
  • Avocados
  • Nuts, nut butters, and seeds: brazil, macadamia, almonds, chia, flax, hemp, pumpkin
  • Meat and poultry: beef, pork, lamb, chicken, turkey (keeping the skin on helps to get more fat)
  • Fish and shellfish (preferably fatty fish, such as salmon, sardines, mackerel, herring)
  • Eggs
  • Tofu
  • Non-starchy vegetables: asparagus, zucchini, spinach, mushrooms, peppers, lettuce, cucumbers, tomatoes, bok choy, green beans, cabbage, celery, olives
  • Berries in moderation
  • Dark chocolate 80-100%
  • Oils/condiments: coconut, olive, avocado, mayonnaise

In my experience, many individuals who are trying the ketogenic diet are not truly in ketosis, and are just eating a low carb diet. Either they are still consuming too many carbohydrates or are relying too heavily on meat and other protein-rich foods to sustain them throughout the day. To give you an example, a truly ketogenic breakfast would look something like this: eggs made with butter, cheese, avocado, spinach, mushrooms, and ½ cup of raspberries topped with plain whipping cream.

As the body transitions from using glucose for energy to fat, it is common to experience a “keto flu”. This can be exacerbated by dehydration and electrolyte losses. The “keto flu” consists of flu-like symptoms, such as irritability, headache, and fatigue, and will likely last 2-7 days. 


Why are people trying the ketogenic diet?

Everybody is different and there will be some individuals who do experience weight loss and better blood sugar control because of this diet. And if this diet is working for you, then that’s great. I want to highlight that for people who rely heavily on refined carbohydrates (e.g. pasta, pizza, white bread, bagels, buns, muffins, low-fibre cereals), switching to this style of eating can often lead to much better blood sugar control, a more nutritionally complete eating pattern, feeling satisfied for longer, and overall improved health. BUT that doesn't mean that all carbohydrates needed to be cut out of the diet to feel this way. We can experience many of the same benefits (and more!) by balancing our meals, eating regularly throughout the day, ensuring there's a protein source at most meals, eating a variety of vegetables and fruit, including fats, and choosing whole grains more often.

If you're still considering this diet, I want to debunk many of the so-called health claims and highlight the risks of following this diet, so that you can make an informed decision.



Weight Loss

The ketogenic diet claims to promote weight or fat loss. The most common reasons for this are:

A) people are eating a lot less calories now that the majority of the foods they used to eat are restricted and they can’t physically eat enough fat to meet their calorie needs each day, and

B) having high fat and protein-rich foods at meals leaves them feeling full for longer after the meal, reducing how much they eat overall throughout the day.

Like most weight-loss studies, all of the studies to date looking at the ketogenic diet and weight loss are short term, usually only lasting a few weeks to a few months. And as we see with most other restrictive diets, the weight loss that is experienced at the beginning eventually plateaus and in most cases, comes back long term. One study showed weight loss peaking at about 5 months, followed by slow weight regain.

Keep in mind that much of the initial weight lost with the ketogenic diet is simply water weight. When we are consuming a standard balanced diet, our body stores carbohydrates for energy in our muscles and liver in the form of glycogen. Glycogen is stored in a hydrated form, attached to water molecules. So when we start restricting carbohydrates and our body has to use up the glycogen stores, it also loses those water molecules stored alongside it. This can be problematic for many because it gives people the impression that they’re losing fat, which acts as a large motivator to keep going, but often that weight loss plateaus over time. Then when a person resumes a balanced diet that includes carbohydrates, they’ll notice a rapid weight gain initially, which can feel discouraging and make us feel like carbs are inherently fattening, but keep in mind that much of these fluctuations are simply to do with water shifts in the body.


Appetite suppression and reduced sugar cravings

The ketones that the body produces have an appetite suppressing effect on the body. This, in addition to the large amount of fat and protein consumed, leads to feeling full for longer and an overall decrease in appetite. Once adapted to the diet, people will often see less sugar cravings. This is likely due to the fact that since almost no carbs are being eaten, there aren't any fluctuations in blood sugar levels, which can typically be a trigger for sugar cravings.


Blood sugar control and Type 2 Diabetes

The ketogenic diet has also been claimed to help manage type-2 diabetes, and in some cases even “reverse” it. Unfortunately, type 2 diabetes can’t be cured. Type 2 diabetes is where the body has difficulties regulating the glucose or sugar in your blood after consuming carbohydrate-rich foods. This can be due to a variety of factors, like insulin resistance and/or genetics. Therefore, in many cases, restricting the foods that the body has a difficult time managing would likely lead to better blood sugar control. However, to say that it “reverses” the condition has not been proven. Just because we’ve removed something we have difficulties processing, doesn’t make the underlying condition go away. There are many people who can achieve great blood sugar control with a balanced, moderate or low-carb diet that includes high quality, low-glycemic carbohydrate sources.


Cancer Therapy (Specifically Brain Cancer)

There is some very early evidence to suggest the ketogenic diet may be helpful to use alongside standard cancer therapies (chemo, radiation, surgery) to potentially improve the effectiveness of treatment. However, the evidence is still very limited and more research is needed to determine its safety and effectiveness. The reason the ketogenic diet may have beneficial effects on cancer growth during treatment might be due to the unfavourable environment that it creates for cancer cells to grow.



Although it may seem tempting to consider the ketogenic diet, here are some potential side effects and concerns about this restrictive eating pattern.

I can of course understand people’s curiosity and intrigue when it comes to the ketogenic diet, especially when it feels like other things that you’ve tried in the past have failed. I also appreciate that some people may find that the ketogenic diet is working well for them and I’m definitely not here to talk you out of it. I do, however, want to ensure that those of you who are following it, are intrigued by it, or are on the fence about embarking on such a restrictive eating pattern, have all the information about what negative impacts it may have on your health and overall lifestyle. It is also very important to note that we do not have enough long term research to know what long term effects the ketogenic diet may have on our health.



The biggest concern with the ketogenic diet is that it restricts most of the foods that have been time and time again associated with long term health, reduced risk of chronic disease, and decreased mortality, such as fruits, starchy vegetables, legumes, certain nuts, and whole grains. While a ketogenic diet can be nutritionally adequate, it must be well-planned and combined with proper supplementation. And there are many foods marketed as “keto-friendly” that aren’t necessarily nutritious. It is much easier to meet our nutritional needs by following a liberalized, varied, balanced eating pattern day to day. If you are following a ketogenic diet, be sure to speak with a registered dietitian to ensure you are meeting your needs.


Negative Relationship with Food

What most researchers don’t take into account when studying the effects of certain diets on our health is how much work it is to follow a restrictive eating pattern and what impact those restrictions may have on a person’s quality of life and mental health. Whenever we restrict our eating, whether it be specific foods, calories, entire food groups, the times of day we can eat, or portion sizes, it can lead to disordered thoughts around food and lead to more stress and anxiety when it comes to planning meals and eating. The keto diet also negates the importance of the social aspect of food and may make social gatherings, travel, and holidays more challenging. You may find yourself missing out on family or friend meals, and experience social isolation to some degree. This diet also requires an all-or-nothing mentality. You can’t “cheat” on keto because as soon as you reintroduce carbohydrates into your eating pattern, you are kicked out of ketosis and any benefits you were hoping to achieve will be negated.


High Cost

With rising food costs, it can be a priority for many families to try and cut costs on their grocery bill wherever possible. Some of the least expensive whole foods include beans, lentils, oatmeal, rice, bananas, apples, pasta, and bread - all of which are not allowed on this diet. Encouraged foods on the ketogenic diet include products like grass-fed meat, nuts, fish, and specialty keto breads/tortillas/pastas/bars, which can be expensive.


High Cholesterol

There is a lot of controversy on if we should be concerned about high cholesterol levels and how that impacts cardiovascular health. We do see that with the increase in saturated fats on a ketogenic diet, many people do experience a rise in cholesterol levels, and LDL cholesterol in particular. Whether or not that rise in cholesterol has a negative impact on someone’s health will depend on a lot of factors, like the subtype of cholesterol, their genetics, smoking, food choices, stress levels, physical activity, and more. If following this diet, it can be beneficial to try to incorporate lots of unsaturated fats from fatty fish, nuts/seeds, avocados, and olive oil. You can read more about different fats here.


Poor Gut Health & Constipation

Even though this diet can include green vegetables, some nuts, and some berries, generally it is quite low in fibre. Fibre feeds the beneficial bacteria that live in our gut. It can also trap and lower cholesterol, help regulate blood sugar levels, regulate bowel movements, and keep us feeling full for longer after eating. Fibre-rich diets have been shown to improve digestive health and saturated fat rich diets have been shown to decrease the number of good bacteria in the gut. Constipation is often a side effect seen with this diet, often due to the lack of fibre and significant increase in fat and protein. One study has suggested a possible increase in a certain bacteria which may lead to a lower risk of developing Alzheimers and seizure frequency, however more research is needed in this area. In some studies, this decrease in good bacteria that was seen seemed to recover after approximately 12-24 weeks, provided that the diet was well-planned and included some fibre.


Low Bone Density

In a study completed with 28 world-class race walkers, half of the participants were put on a ketogenic diet for three weeks while the half consumed a high carb diet. Prior to the study, blood was drawn from each participant to check for markers of bone health. After three weeks, a second blood sample was drawn and tested. It was found that in those following a ketogenic diet, markers of bone breakdown tend to be higher while markers of bone formation are lower. Markers were generally unchanged in participants who followed a high carb diet. Although the reason for this observed difference is currently unknown, the study does set a foundation for establishing that the keto diet may impact our bone health. More studies are of course needed.


Exercise performance

There are mixed results on whether or not the ketogenic diet impairs or improves exercise performance. One study showed that people on the keto diet performed worse at anaerobic (short, high intensity) tasks than those eating more carbohydrates. However, the people tested were only on the diet for a short time. Earlier research has also found that short-term keto diets (between 1-7 days) are harmful to endurance capacity and the performance of extended exercise. This is likely because the body has not yet adapted to the state of ketosis at that point, also known as keto-adaptation. Other studies have shown an improvement in performance and better fat oxidation in endurance athletes who have been on the ketogenic diet for at least 3 months compared to high-carbohydrate diets.



  • Keto is a high fat, low carbohydrate diet with the goal of putting your body into ketosis by consuming less than 20-25g of carbohydrates per day.
  • There is no conclusive evidence that the keto diet is superior to a balanced diet
  • Following the keto diet long-term may have negative impacts on your physical and mental well-being


As always, nutrition evidence is continuously evolving. While more evidence may continue to emerge over the next decade about the clinical use of this diet for specific conditions, such as brain cancer, Alzheimer’s, or diabetes, it is important to remember that any restrictive eating pattern is never without its side effects and if appropriate for an individual’s specific condition, should be started with the support of a registered dietitian to ensure it is safe and adequate. We also have to consider the impact that any dietary restriction will have on your overall quality of life and relationship with food, and whether or not it is sustainable for you. 


Written by: Tamara Smallwood, Samira Razmjou, and Liz Powell, RD



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