Low carb diets restrict carbohydrates, principally in wheat, rice, corn, potatoes and sugar.
Instead, you eat a higher proportion of natural fats found in fresh produce like meat, oily fish, avocados, eggs, nuts and butter. Fats are not sourced from fried or processed junk food.
These diets have been used for over a century and there are over 20 studies demonstrating the superiority of Low Carb diets over Low Fat diets for weight loss and the treatment of type 2 diabetes.
Let’s look at the science and myths.
MYTH 1: CARBS ARE ESSENTIAL FOR ENERGY
There are essential fats (fatty acids) and proteins (amino acids) which you cannot manufacture in your body so they must come from the diet. However, dietary carbohydrates, which are broken down to glucose, are the only ‘non’ essential macronutrient in the diet.
Yes, your brain needs glucose to function, but that doesn’t mean you have to eat it. Your body has a clever way of making its own glucose in the liver when required (a process called gluconeogenesis).
From an evolutionary perspective, it makes sense. As a species, we evolved to cope with extended periods of fasting. The body can cleverly switch to using an alternative fuel source called ketones, produced when the body starts burning its own fat stories. It’s a state called nutritional ‘ketosis’.
MYTH 2: KETOSIS IS DANGEROUS
Ketosis is often confused with another medical situation, called ketoacidosis. It sounds similar, but ketoacidosis is a complication of uncontrolled diabetes, which can be fatal, a far cry from a state of nutritional ketosis.
Even babies, soon after they are born, are in a natural state of ketosis.
MYTH 3: EATING FAT WILL MAKE YOU FAT
While fat has more “calories” than carbs per gram, it’s what happens in the body that matters. Unlike fat, carbohydrates (particularly refined carbs) are a potent stimulator of your fat-storing hormone, insulin.
Consistently high insulin levels means a consistent tendency to keep fat stored. That’s when those kilos creep up on you until one day you discover the spare roll around your waist (also known as the “insulin” roll).
Also, fat meals keep you fuller for longer so you end up eating less food. Whereas, refined carbs keep you “always hungry”, a phenomenon recently described by Harvard Doctor David Ludwig.
So, eating fat won’t “make you fat” because it controls satiety and reduces your requirement for (fat-storing) insulin.
MYTH 4: LOW FAT IS BEST
There is now ample evidence that the demonisation of fat has been misguided. UK researchers analysed all of the studies which were available to the US committee before the introduction of the 1977 US dietary fat guidelines. Of the 6 high quality trials that were available, none of the dietary fat interventions made a difference.
“There was no evidence whatsoever from these trials to support the ‘low fat’ mandate” said lead author and obesity expert, Dr Zoe Harcombe.
Nevertheless, the committee forged ahead. It instituted guidelines recommending population-wide dietary fat restriction, which was widely adopted by other western nations.
Fast forward several decades and we’re now confronted with a tsunami of diabetes and obesity, much of it blamed on the erroneous low fat, carbohydrate-rich diet.
The slow realisation that many fats are healthy is seen in the embracing of the high-fat Mediterranean diet and in the latest iteration of the US Dietary Guidelines where they removed the cap on total fats in a healthy diet.
MYTH 5: SATURATED FAT WILL ‘CLOG’ YOUR ARTERIES
Despite several major clinical trials and analyses failing to demonstrate a link between saturated fat consumption and heart disease, the myth still persists.
Saturated fat is often talked about in isolation, but the reality is that food contains a mixture of different kinds of fats. For example, health authorities encourage consumption of “mono-unsaturated olive oil” but it actually consists of about 14% saturated fat. Even 50% of the fat in breast milk, is saturated fat.
Recently, top cardiologist and former president of the World Heart Federation, Prof Salim Yusuf addressed a group of doctors at a Cardiology Update meeting. “Contrary to common beliefs, the current recommendations to reduce saturated fats have no scientific basis”, said Prof Yusuf.
He presented the latest unpublished findings of a large ongoing study involving 140,000 people in 17 countries, which showed the higher the fat consumption, the lower your risk of heart disease. Conversely, the higher your carbohydrate consumption, the higher your risk of heart disease. Yet, this is the advice our health authorities have been recommending to people for decades.
CHALLENGES MOVING FORWARD
Should everyone go on a low carb diet? It’s a personal choice, but there are distinct advantages in its overall palatability and role in controlling hunger and weight loss.
There are doctors in the US and the UK who have been ignoring the current dietary guidelines and recommending Low Carb diets to people for years, some for over a decade.
However, in Australia, we’ve seen some examples of health practitioners castigated for issuing this very advice. Dietitian Jennifer Elliott and orthopedic surgeon, Dr Gary Fettke have reportedly been sanctioned for giving low carb dietary advice to their own patients.
Perhaps there might be less resistance in this country following the recent publication of a robust study by Australia’s leading scientific organisation, the CSIRO.
“The most amazing benefit of the low-carbohydrate diet was the reduction in the patients [with type-2 diabetes] medication levels, which was more than double the amount than the volunteers following the lifestyle program with the high-carbohydrate diet plan”, says the lead investigator, Associate Professor Grant Brinkworth.
These researchers are now suggesting that the dietary guidelines need a rethink.
While the study from the CSIRO confirms original work completed by Westman and colleagues a decade ago, it may be that the high profile of this organisation and the motivation to promote its new book will help to initiate change.
Change takes time. Lets hope it doesn’t come at the cost of another rise in largely avoidable, lifestyle related diseases like type 2 diabetes and obesity.