The Low Down on Low Carb

by PREKURE | Aug 11, 2022 | Metabolic Health

Unless you have been living under a rock, you’ve probably heard about low carb diets in some way, shape or form in the past few years. PREKURE’s own Chief Science Officer Prof Grant Schofield and Dietician Associate Professor Caryn Zinn have even co-authored a few books on the subject. These books delve into the science and practice of implementing a low carb diet. You can find What The Fat? What The Fast? What The Face and What The Fat? Cookbook at any good bookstore. If reading this blog post piques your interest, we definitely recommend checking them out! This blog post is a quick-fire overview of low carb diets and should not be substituted for medical advice.

What are low carb diets?

‘I’m low carb’ is a phrase we have all probably heard (or identify with). So what exactly are low carb diets? In the diet there are three main macronutrients: protein, carbohydrates and fat. For a long time it was thought that carbohydrates were essential to maintain blood sugar levels and brain function. It was thought that reducing our intake would have dire consequences and result in our blood sugar plummeting and our brain incapable of adequately functioning because the brain could only use carbohydrates for energy. This isn’t exactly the case. Fat and protein are essential because they support the milieu of biological processes within the body and restricting them can impair growth and normal hormonal function [1]. Carbohydrates, on the other hand, are not essential. The normal amount of sugar in the blood to achieve homeostasis is between 4-5 mmol/L or about a teaspoon worth of sugar. We can easily achieve this with less than the recommended 300 g of carbohydrates per day. Even so, if our blood sugar starts to drop our bodies have adapted to ensure we maintain stable blood sugar through a process known as gluconeogenesis. There are many benefits associated with low carb diets including weight loss, improved metabolic health and even improved cognitive function [1]. Research shows that low carb diets are a safe and effective treatment for type 2 diabetes and can even result in reversal of the condition [2]. You can read our blog post on this here. Today, studies are exploring how very low carb diets can be used as adjuvant treatments in diseases like cancer, Alzheimers, dementia and other neurological conditions and metabolic conditions – there will likely be many new and exciting discoveries of the power of diet in the treatment of disease in the coming years.

What types of low carb diets are there?

Let’s take a quick look at the various interpretations of low carb:

1. Atkins Diet

The Atkins diet was developed in the 1960’s by a cardiologist named Dr Robert Atkins. The diet is focused on reducing the volume of carbs consumed and focusing on protein and healthy fats. A recent systematic review revealed that the Atkins diet produces clinically significant weight loss [3]. Interestingly, there appears to be a ballooning of Atkins processed products available in supermarkets worldwide. Given what we are coming to know about the importance of the degree to which foods have been processed, it is worth considering whether a more commercial-based Atkins diet will produce the same favourable results [4, 5].

2. Low Carb Diet

While there is no universally accepted definition for low carbohydrate diets, Professor Richard Feinman in 2015 established a threshold of less than 130 g of carbohydrate per day [6]. This has been an acceptable upper threshold that many researchers and clinicians agree denotes a low carbohydrate diet. Low carb diets are intended to prioritise whole, unprocessed foods and reduce inflammatory compounds like hydrogenated seed oils and ultra-processed foods. The typical macronutrient split on a low carb diet is ≤ 130g carbs, approximately 1.2 – 1.6g protein per kg of body weight and fat comprises the remaining calories [7].

3. Keto Diet

The keto (or ketogenic) diet is a very low carbohydrate diet intended to induce a state known as nutritional ketosis [7]. Typically, our bodies use glucose (or sugar) for energy. When we reduce the carbohydrates in our diet our body uses a by-product of fat known as ketones. The most commonly known (and most abundant ketone) is beta-hydroxybutyrate and when in a state of nutritional ketosis you can expect the ketones circulating in your blood to be between 0.5 – 3mmol/L. The generally accepted threshold for carbohydrate on a keto diet is between 20 – 50g; however, it is worth noting that in practice this may vary and lower or higher volumes of carbohydrates may elicit a state of nutritional ketosis [7]. Typically on a ketogenic diet less than 10% of calories come from carbohydrates, more than 80% from fat and protein is set at a moderate level. It used to be thought that too much protein would ‘kick you out’ of nutritional ketosis but it appears that this is not the case.

4. Carnivore Diet

It’s exactly what it sounds like. The carnivore diet is the most extreme low carbohydrate diet. Usually people who follow this diet will eat only meat or may include products like eggs, cheese and yoghurt (high fat animal by-products). There isn’t an overwhelming body of evidence for this diet pattern and there are some concerns regarding the long term impacts it may have on gut health given the lack of dietary diversity and fibre.

If we were to examine them on a spectrum, Atkins and low carbohydrate diets would be less restrictive while keto and carnivores would be more restrictive. Keto may be a powerful therapeutic tool but whether such an extreme level of restriction is required for weight loss and general health, or whether a low carb diet would suffice, has not yet been determined [7].

Are low carb and keto fad diets?

Although it seems as though low carb diets sprung into existence in recent years, they have actually been around for well over 100 years [7]. In the early 1900’s very low carb diets (VLCDs) were used as the first line treatment for epilepsy and type 1 diabetes [7]. There are people who still believe that low carb diets are fads that have weak scientific evidence to back them up; however, this is not the case. There is a growing body of research that illustrates that restricting carbohydrates in the diet has positive effects on metabolic health, weight and cognitive function [7]. Reducing carbohydrate content is most effective in those with poor metabolic health (i.e. insulin resistant) because it acts as a way to reverse this process and help the cells recognise insulin once more [7]. While there are still concerns related to saturated fat and red meat consumption and their impact on the risk of developing chronic diseases like heart disease, the evidence for this hypothesis is weak [7]. It appears that high carbohydrates (specifically ultra-processed acellular carbohydrates) and poor quality meat that is high in hydrogenated fats may be the real issue. Again, we find ourselves confronted with the importance of diet quality.

What can I eat on a low carb or keto diet?

That all sounds good and well, but what do you actually eat if you are on a low carb or keto diet? And do you need to track carbs and calories? Well, research shows that increasing the amount of fat and protein in the diet often leads to a natural reduction in the amount of food eaten [7]. Scientific studies have shown that on a low carb diet, when participants are instructed to eat ad libitum (or eating till full) their total calories consumed decreases [7]. This is likely due to the satiating nature of protein and fats and (if you focus on a whole food approach) the fibre you will get from vegetables, nuts, seeds and berries. Basically, the short answer is focus on food quality rather than calories and you should find yourself in a great place.

Here’s a quick guide to what’s in and what’s out when you are looking to go low. Remember, this is just a snapshot of the types of foods you can include in your diet when going low.