It has been quite some time since a diet has gained as much traction as the ketogenic diet. You would be hard pressed to scroll through your various social media accounts without seeing someone’s transformative photos of their “keto journey.”  So, what is the real deal with this diet, and what are the nutritional implications of joining in?

First fats; now carbs

Those of you who lived through the 1980’s zero-fat era will likely remember that everything became “fat-free” due to the science surrounding heart disease and fat in the diet. Since then, we have learned that fat certainly has a place in the diet, and the link between heart disease and fat intake is not as simple as we once thought. 

The ketogenic diet

The ketogenic diet focuses on limiting a different macronutrient: “carbohydrates” (aka sugar or glucose). The keto diet is a very low-carb, moderate-protein, high-fat diet and stems from 1920’s research where the diet was used to treat epilepsy with some success. Today the diet is popular with individuals pursuing weight loss.

A core principle of a ketogenic diet is to limit carbohydrate intake to 15-60 grams per day. At the higher end of this range, this roughly translates to one cup of cooked rice and a small piece of fruit. This keeps the body in a state of ketosis, the process of burning fat stores rather than using glucose (or stored glycogen) for energy.

The keto diet also limits protein to ensure the body stays in ketosis. Generally, fat will make up 60-90% of calories, protein 15-20% and carbohydrates <5%.

What is going on in your body on a keto diet?

Foods that contain carbohydrates are broken down into glucose (a form of sugar), the simplest form of a carbohydrate that is taken into cells and used as energy. The body, particularly the brain, prefers carbohydrate as its primary source of fuel. The average Canadian adult consumes about 235g of carbohydrate daily. When the intake of carbohydrates is significantly limited, the body shifts into a state of ketosis and burns stored fat as its source of energy. This results in a buildup of ketone bodies in the blood which the body can then use as its primary fuel source

The breakdown of fat for fuel and creation of ketone bodies is a normal physiological response to low-carb diets. However, ketosis should not be confused with ketoacidosis, which can occur in diabetes and be fatal.

Diet details

Many foods contain carbohydrates, and these are largely restricted on a keto diet:

  • grain products (bread, pasta, rice, quinoa, cereals, etc.)
  • fruit (juices and whole fruits)
  • starchy vegetables (corn, beets, squash, potatoes, etc.)
  • milk and milk products
  • pulses
  • Alcohol

It is interesting to note that there are many variations of the keto diet circulating on the internet. The most common and simple-to-follow version is known as “the modified Atkins.” This approach limits adults to 15-20 g of carbohydrates daily (one slice of bread OR one apple OR 1/3 cup of rice), is moderate in protein and promotes a very high fat intake. 

Short-term outcomes

First and foremost, individuals who have tried the ketogenic diet often express that they feel full and satisfied throughout the day. This is due to the high amount of fat and fibre in the diet. Studies show that individuals who followed ketogenic diets saw reductions in body weight and improvements in blood lipid parameters.

In other studiesindividuals with Type 2 diabetes who followed a keto diet demonstrated improvements in blood sugar management and saw weight loss. Nonetheless, it is important to consider that due to a reduced level of calories and limited protein, a bulk of this weight loss could be attributed to loss of lean muscle mass.

In trials with athletes, results showed performance on a keto diet was often impaired due to increased demand for oxygen on the body. Interestingly, athletes often report “feeling better.” However, prior to starting the keto diet, most of the participants were skipping meals, eating high amounts of fast foods and often not eating high quality meals.Less desirable side effects of this diet can include bloating, gas, constipation, and diarrhea.

Long-term outcomes

While short-term studies have indicated some positive results, we really don’t know how the body responds in the long term. Many people find this style of eating quite hard to follow because food choices are limited. In a culture that often connects and socializes over meals, following a restrictive pattern of eating may make these gatherings stressful and unpleasant.

While some data show healthier cholesterol levels and weight loss in the initial stages of being on a keto diet, science has not been able to determine if these benefits continue in the long run. Some evidence shows that following a ketogenic diet intermittently with a Mediterranean diet has lasting weight loss effects up to one year. However, there is little data to know what happens beyond that.

For the most part, while diets studied for greater lengths of time show beneficial effects in the short term (e.g. weight loss, improved health markers), these effects may diminish or disappear one to two years down the road. 

Bottom line

The ketogenic diet certainly seems to have its perks. However, just like any pattern or style of eating that includes the word “diet,” ultimately that is what it is - a diet. Keep in mind that eating is meant to be a lifestyle, not a fix or a short-term solution.

Before starting any new eating plan, do your research, assess your goals and motivations and consider whether you can or want to eat this way for the rest of your life. Consider working with a registered dietitian who can help you meet your specific goals in a healthy and sustainable way.

 

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Barbara Winzeler, RD

Registered Dietitian

Barbara (BSc, RD) is an Edmonton-based registered dietitian and blogger for Nourish Move Thrive®. She enjoys helping her clients develop healthy relationships with food and themselves.

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