With all the talk about low carbohydrate diets, you may feel like carbohydrates are the enemy. Maybe you’ve even tried following a low carbohydrate diet or are thinking about starting one. The media makes them sound very appealing, and low carbohydrate diets make all kinds of health promises.

But should you really follow one?

Today, we’ll cover the basics of what a low carbohydrate diet is, what it’s typically used for, and whether or not it’s a good idea to follow one.

What are Carbohydrates?

Carbohydrates (carbs) are one of the three macronutrients found in food and drinks. This means that although carbohydrates cannot be seen with the naked eye, this macronutrient is one of three important building block nutrients in our food supply, and is necessary for sustaining life. Foods that come to mind when most people think about carbs include rice, pasta, potatoes, bread, cereals, and pastries. As a group, these foods are know as Grains & Starches. Other foods that contain carbs include some dairy products, fruit, some vegetables and some meat alternatives.

When we eat foods that contain carbohydrates, the digestive system breaks them down into glucose (another name for blood sugar). The glucose is then absorbed and used as energy to fuel your body. Carbohydrates are the body’s preferred source of fuel.

Here’s a simple way of thinking about this:

Foods containing carbs → supply of fuel (glucose) for the body.

That fuel supply (glucose) → physical and mental energy, sustained vitality for living.

When your body isn’t getting enough of the foods that contain high amount (or any) carbohydrates, it shifts into a state called ketosis.

What is Ketosis?

Our body typically stores enough glucose to provide us with energy between meals. However, in the case of starvation (real starvation or what the body interprets as starvation), such as when we consume a low carbohydrate diet, glucose eventually runs out.

After about three to four days of carbohydrate or calorie restriction, the body needs an alternate source of fuel. Since fat is readily stored and available in the body, the body is able to breakdown and use stored fat to produce the needed alternate souce of energy called ketones. Ketosis describes the state in which the body is using ketones as its primary fuel source instead of glucose derived from carbohydrate. Ketones become abundant in the liver during this time.

What is a Low Carb Diet?

The goal of a low carbohydrate diet is to exclude or reduce carbohydrates. This is achieved by increasing fat or protein in the diet to make up for the lack of carbohydrates.

There are many different types of low carbohydrate diets, including:

  • The ketogenic (keto) diet, which is low carbohydrate, moderate protein, and high fat. The goal of the ketogenic diet is to shift the body into ketosis.
  • The Atkins diet, which is low carbohydrate, and high protein.
  • The Dukan diet, which is low carbohydrate, low fat, and high protein.

For today’s purposes, we will be focusing on the ketogenic diet.

Many foods are not allowed on a keto diet. These include:

  • Grains (e.g. cereals, bread, pasta, rice)
  • Meat alternatives a.k.a Legumes  (e.g. beans, peas, and lentils)
  • Many fruits (e.g. bananas, apples, oranges, dried fruit)
  • Starchy vegetables (e.g. potatoes, corn, sweet potatoes and butternut squash)
  • Alcohol
  • Sugary foods (e.g. chocolate, candy, baked goods, pastries, regular pop, fruit juice)
  • Certain dairy products (e.g. milk)

As you can see, the keto diet is quite restrictive, and eliminates many foods that would otherwise be part of a healthy, well-balanced diet.

What is the Keto Diet Used for?

Treatment of Drug-Resistant Epilepsy

A low carbohydrate, ketogenic diet is often used as a treatment for epilepsy that isn’t responding to treatment with drugs. Studies have shown that when used correctly, the ketogenic diet can reduce seizure frequency for people with epilepsy. When used to treat epilepsy, the diet must contain less than 10% of calories from carbohydrates. Since carbohydrate intake is so low, it’s best to follow this kind of diet under medical supervision.

Treatment of Glioblastoma

Low carbohydrate diets are still in the very early experimental stage as a possible treatment for this type of brain cancer. It has not yet been tested in humans.

What are the Cons of a Keto Diet?

While there are some medical conditions in which the ketogenic diet can be an effective treatment, the negatives of the diet outweigh the potential positives. Here are a few of the negative sides of the ketogenic diet:

Lack of Data That Supports Sustainable Weight Loss

Low carbohydrate diets are often used as a weight loss strategy. Very low carbohydrate and ketogenic diets lead to greater weight loss in the short term (under 6 months) compared to higher carbohydrate diets. However, there is no difference in weight loss between the two diets by 12 months. In other words, there is no evidence that the keto diet supports weight loss maintenance in the long term.

Given what we know of the dangers of weight cycling (losing and regaining weight repeatedly), this is a potentially harmful effect of the keto diet.

Blood Sugar Management

Studies have shown that low carbohydrate diets can improve blood sugar management in people with type 2 diabetes in the short-term. However, studies have also shown that simply changing the types of carbohydrates consumed (to include more whole grains and high fibre carbohydrates) is also an effective strategy for blood sugar management. Plus, studies fail to show any long-term improvements in blood sugar management on a low carbohydrate diet.

Inadequate Micronutrient Intake

A study looking at a 12-week ketogenic diet found that throughout the diet, intakes of magnesium, calcium, iron, phosphorus, and potassium were less than what is typically recommended. Although blood levels of most micronutrients remained in the normal range, it is possible that if the diet went for longer than 12 weeks, that deficiencies may have occurred.

Deficiencies in these micronutrients can lead to harmful effects in the body. For example, low magnesium levels can lead to seizures and abnormal heart rhythms. Low calcium levels can lead to poor bone health, as well as heart problems. Low iron levels can lead to extreme fatigue, and poor brain functioning. Low phosphorus levels can lead to muscle weakness, bone weakening and in extreme cases, coma or death. Low potassium levels can lead to abnormal heart rhythms, muscle weakness, and even paralysis.

If aiming to follow a keto diet for any reason, it’s important to keep the averse health risks of micronutrient deficiencies in mind.

Inadequate Fibre Intake

Since the keto diet eliminates legumes, whole grains, most fruits, and many vegetables, it can be very difficult to get enough fibre. This can lead to constipation, as well as potential changes to your gut microbiota (the microorganisms, like bacteria, living in your gut that are critical to healthy digestion).

Your gut microbiota plays several important roles in the body, including vitamin production and immune system regulation. Since fibre acts as a fuel source for our gut microbes, not getting enough could be harmful to our gut ecosystem.

Increased Risk of Heart Disease

Ketogenic diets are often high in saturated fat. Several studies have shown that low carbohydrate diets like the keto diet can lead to increases in LDL (bad) cholesterol. Since high LDL-cholesterol is a risk factor for heart disease it is easy to see that this is not a desirable change.

Kidney Health

The emphasis on high-fat, animal-based foods, along with cutting out many fruits and vegetables, promotes the production of kidney stones. Studies also show that high intake of animal protein may lead to an increased risk of developing chronic kidney disease. For people with pre-existing kidney disease, high protein intake can worsen kidney function.

Increased Risk of Birth Defects

A study of 11,285 women found that women who consumed low-carbohydrate diets in the year before becoming pregnant were 30% more likely to have a baby with a neural tube defect. Low levels of folic acid, a key nutrient that protects against neural tube defects, was found to be common in mothers whose babies were affected.

Increased Risk of Osteoporosis

Studies looking at the effect of the ketogenic diet on bone mineral density (a marker of bone health) in 68 children following the ketogenic diet for the treatment of epilepsy, showed a significant reduction in bone mineral density over the course of the 8 year study. This could be because without supplementation, keto diets are often low in calcium, which is important for the building and maintenance of healthy bones.

Final Thoughts

While there are some benefits of low carbohydrate diets like the ketogenic diet for specific medical conditions (like epilepsy), there are many potential pitfalls of following such a restrictive diet. These include increased risk of heart disease, kidney disease, osteoporosis, and birth defects. It also does not provide enough of many vital nutrients, like folic acid, calcium, and fibre.

Rather than focusing on restriction, focus on nutritious foods that you can add to your diet. This includes whole grains, fruits, vegetables, lean proteins of the animal and plant variety, dairy and dairy alternatives, nuts, and seeds. By eating a variety of foods, you are ensured that your body is receiving all the nutrients it needs to keep you energized and well.

Not sure where to start? Book an appointment with our Registered Dietitian Sylvia Kerr today and get the guidance you’ve been looking for.