Given the recent surge in popularity, you may have heard of low carb diets. Low carb diets are nothing new – in fact we could argue that historically, humans lived off low carb diets. To clarify, when we talk about low carbohydrate diets we are essentially referring to lower carbohydrate diets; that is, diets that consist of considerably lower carbohydrate intake then what is generally advertised via the food pyramid, food plate and typical/mainstream nutrition advice.
Some known examples of low carb diets include the Paleo diet, the ketogenic diet and the Atkins diet. Generally, a low carb diet limits your carbohydrate intake to 30% maximum of your total energy intake per day. A standard Western diet tends to incorporate more like 60% of carbohydrates per day.
Standard Western Diet
Low – Carb diets
In chemistry terms, carbohydrates are molecules made up of hydrogen, oxygen and carbon. In dietary terms, carbohydrates consist of starches, sugars and fibers found in our foods. Internally, these all act a little differently and are utilised by our bodies in different ways. Generally speaking, carbohydrates are utilised by our body to create energy molecules known as adenosine triphosphate (ATP).
When metabolised (broken down) to their simplest form, carbohydrates enter energy producing processes, known as glycolysis, the Krebs cycle and the electron transport chain to produce ATP – the body’s energy currency.
ATP
Not all carbohydrates are utilised solely for energy production. For example, resistant starches and fiber can act as prebiotics and feed our good gut bacteria in our colon (to read more about why our gut bacteria is vitally important click here). Carbohydrates, however, are not the only macronutrient our body can use for energy production. The body can also use fat for this purpose.
Basically speaking, fatty acids yield much more ATP, or energy, compared with carbohydrates. When broken down in the liver, fatty acids produce what is called ketone bodies. Ketone bodies can enter the Krebs cycle to generate ATP. Burning ketones for fuel may be seen as ‘cleaner’, in that they utilise less chemical helpers in the production of ATP (when compared to glucose). Think of it as burning a fire inside your home versus using clean natural gas to try and warm up. Both achieve the same goal, but one leaves the room dirty, with more ‘junk’ left behind.
A study by researchers at the University of Connecticut has shown that low carbohydrate diets are more effective in lowering both levels (markers) of inflammation and saturated fat in the blood. These markers included pro-inflammatory cytokines, chemokines and adhesion molecules. The lead researcher concluded that carbohydrates rather than fat exert more significance on nutritionally derived inflammation [1]. Further studies have backed these findings, finding low carb diets prevented the increase in markers of systemic inflammation, including CRP, IL6 and TNF-a. [2,3]
[1] www.sciencedaily.com/releases/2007/12/071203091236.htm
[2] https://www.ncbi.nlm.nih.gov/pubmed/26011473
[3] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5981249/
Diets low in carbohydrates greatly alter the lipid make-up of the blood. This refers to the levels of HDL cholesterol, LDL cholesterol and triglycerides – the main components associated with heart disease. Broadly speaking, we aim to have a blood lipid profile that sees a high(er) level of HDL cholesterol in comparison to low(er) levels of LDL cholesterol and triglycerides. Low carbohydrate diets promote such a profile [4,5].
One 20-year long study of over 80,000 women [4] showed that those eating a lower carbohydrate diet had a 30% lower risk of heart disease than those eating a high carbohydrate, low fat diet. Further randomised studies from OmniHeart showed that lower carb intake did a better job of lowering ‘bad’ cholesterol and blood pressure than what many considered to be a ‘healthy’ high carbohydrate diet.
[4] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4351995/
[5] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5452247/
[6] https://www.medscape.org/viewarticle/523041
Low carb diets, through multiple studies have shown to dramatically decrease the weight and body mass of overweight and obese individuals. Furthermore, when continued, the weight has been shown to stay off [7,8]. As an additional and crucial point, the weight loss occurred through fat loss – first through visceral fat then through skeletal fat deposits. This is vitally important as visceral fat refers to the fat that surrounds the organs, and poses a giant threat to mortality. Also, muscle maintenance is kept and even increased through these diets.
There are various mechanisms through which this weight loss is achieved, the main one being increased lipolysis and fatty-acid usage. Lipolysis is the process by which fatty acids are released from fat cells so that they may enter the krebs cycle to produce energy. These fat cells can be found in adipose tissue – and is the reason why we see weight loss from low carb diets.
When restricting carbohydrates, fat consumption does not translate to fat storage. It is in fact when carbohydrates and thus levels of insulin are increased that we see increased rates of fat storage within our body.
[7] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6038311/
[8] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2716748/
Ketone bodies have been demonstrated as excellent fuel sources for the brain. They exert neuroprotective and cognitive enhancing effects, whilst protecting against neurological conditions such as epilepsy, Alzheimer’s, dementia, Parkinson’s and minimising damage from traumatic brain injuries. [3,9,10]
To add to this, ketosis seems to favour the conversion of glutamate to GABA, promoting a calm state, and warding off excitotoxicity – a phenomenon associated with anxiety, tension, restlessness and brain fog. [11]
[9] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1940242/
[10] https://www.ucsf.edu/news/2017/09/408366/how-ketogenic-diets-curb-inflammation-brain
[11] https://www.psychologytoday.com/blog/evolutionary-psychiatry/201104/your-brain-ketones
Lower carbohydrate diets will drastically reduce the amount of insulin excreted, and lower our blood sugar levels, keeping them at a healthy, stable level. This has far reaching effects, including significantly lowering the risk of developing diabetes (which itself has far reaching consequences) and regulating our hormones.
Low carb diets exert significant effects on our hormones that regulate appetite, hunger and satiety (feeling full). Low carb diets see a fall in ghrelin (the hunger hormone), whilst rising levels of CCK (the feeling full hormone). This may contribute to it’s effectiveness in promoting weight loss.
Metabolic syndrome refers to the presence of three of the five following conditions: high blood pressure, high fasting blood glucose, expansive waist line (central obesity), high levels of triglycerides, low levels of HDL (good cholesterol). All of these conditions are indicative of under-expressive mitochondria.
Mitochondria are the cell’s powerhouses – the site at which most of the ATP (energy) is generated. If these mitochondria underperform, or are low in numbers – we experience disease. Low carb diets not only enhance the efficiency of mitochondria – but increase the number of mitochondria themselves [12].
[12] https://www.ncbi.nlm.nih.gov/pubmed/30027365
Mitochondria (in red)
This is a rare condition in which blood ketones reach a dangerously high level. It is extremely rare (even if you eat a low carb diet and are in ketosis), unless you are a type 1 diabetic. A type 1 diabetic’s body produces a high level of ketone bodies due to its inability to utilise glucose for energy, as the insulin needed to get glucose into the cells for energy production is not present in type 1 diabetes.
The ‘keto flu’
As our bodies begin to shift their major fuel source from carbohydrates to fat, we may experience flu like symptoms, mainly a bit of nausea. These symptoms are a little rare to experience, but do exist, and usually do not persist past a week or two.
Some common myths of low carb diets
“Carbohydrates are our bodies preferred fuel source; that’s why they are chosen first over ketone bodies for energy.”
In a way, this is true, as the body will utilise carbohydrates before it will turn to fat for fuel. However, to say this is indicative of preference is a little misleading. For example, if we ingest alcohol, our body will burn the alcohol for fuel before it will look to burn carbohydrates. If by this reasoning, we then go on to say that alcohol is the body’s preferred fuel source, we are being misleading.
“Eating higher fat will raise my cholesterol / High fats and cholesterol cause heart disease”
The ratio of our HDL to LDL cholesterol is usually seen as (one of) the major markers risk of heart disease. That is to say that high levels of LDL as compared to low levels of HDL (and high levels of cholesterol overall), greatly increase the risk of developing heart disease. With that being said, the effect of dietary cholesterol on our blood cholesterol is negligible at best. Furthermore, high levels of HDL cholesterol are extremely beneficial due to the role they play. HDL takes cholesterol from the cells, blood and tissue and delivers it back to the liver, preventing a dangerous level of cholesterol to be in circulation. Cholesterol is vitally important to every cell in our body, and is vital for hormone production.
As a generalisation – there is still much to learn about cholesterol within the health paradigm. New insights into atherosclerosis and heart disease are showing that the “cholesterol and saturated fats are bad” mantra is long becoming an obsolete assertion. The bandwidth of focus is narrowing in on systemic inflammation as the root cause, or to put another way – heart disease and fatty plaques, though they contain cholesterol, cannot exist in an environment void of inflammation.
“Brains prefer carbohydrates”
Though only taking up 2% of our body weight, our brains are oxygen and energy hogs! It is true that the brain does use glucose for fuel, but can however – utilise ketone bodies, a process that exerts many more benefits than its sugary counterpart. These benefits can be seen in the ‘enhance brain functioning’ section of this article.
“What about the food pyramid/plate?”
The science and clinical trials (or lack thereof) that lead to the common food pyramid/suggestions may be described as questionable at best. Since the inception (1988) of these illustrated suggestions, intake of fats drastically reduced, with a coupled increase in carbohydrate intake. An odd parallel phenomena associated with this introduction was the steady increase in diabetes, obesity and instances of heart disease. This food pyramid came about through the interplay of politics, industry bias, ego and basically put – bad science. To illustrate this point – the current Australian Dietary guideline actually has a picture of a crumpet in its ‘eat most’ foods category. This topic is far too big a discussion for a paragraph in a blog entry, and perhaps will be added as its own article at a later date.