First stop… What is the keto diet?
You’ll see it as ‘keto diet’, ‘ketogenic diet’, ‘ketosis diet’ and so on, let’s save ourselves a few key stokes and call it the KD. According to the Ketogenic Diet Plan Resources website, a ketogenic diet plan:
“… improves your health through a metabolic switch in the primary cellular fuel source to which your body and brain are adapted. When your metabolism switches from relying on carbohydrate-based fuels (glucose from starch and sugar) to fat-based fuels and fat metabolism products called ketones, positive changes in the health of your cells occur, and this translates into better overall health. “
Sounds good, but what does ‘switching your primary cellular fuel source’ entail? Sounds a little tricky, in knowing a little about the finely tuned 'machine' the human body is (as my husband reminds me), the thought of switching anything seems like a big ask.
Filler up, fueling
Under normal conditions our body appears to happily chug along on its diet of mainly carbs (around 60%), plus some protein, and a bit of fat thrown in for good measure (so to speak). Carbs are integral in the generation of energy for activity, and for basic physiological processes. For example, the brain runs almost entirely on glucose, our eyes rely on glucose, as do muscle cells and much more. To understand the KD we need to understand what happens when carbs no longer act as our primary fuel and how we can purposefully create this situation.
What happens when our supply of glucose runs short?
When the glucose trotting about in our bodies and our stored glucose, glycogen, is depleted, the carbohydrate piggy bank is all but spent. We’ve all heard of people stuck up on snow covered peaks for days, or months on end even with nothing but a Mars bar. As the hours and days pass and the Mars dwindles to a few crumbs, in order to conserve any remaining glucose, the body undergoes an amazing adaptation, enter ketosis. Ketosis occurs when our primary fuel (yes you got it, carbs) runs low and whatever small amount remains needs to be preserved; our bodies take the bold move of switching to the use of fat for fuel. I can hear a few of you clapping your hands at the thought of this, 'tell me more' you say, but hold your horses, there’s more to it than that… groans… come on guys, didn't you expect that? We'll get to this soon.
What happens when we are in ketosis?
The process of ketosis produces ketones (also referred to as ketone bodies, of course, few things in nutrition have just one name); it's ketones that become our 'backup' fuel. If you’ve ever fasted, or gone without food for a good period of time you may have noticed a sweet smell on your breath, or someone might have noted this for you, likely you were in ketosis and what your expiring is a bi-product of ketone oxidation, acetone. 'Oh yer, I've had that happen'... yes so likely we've all experienced this.
Ketones the body produces from oxidising (burning) fat, move from our liver to other tissue, such as the brain to be used as fuel in the fuel cycles. In mobilising ketones as a fuel the body can conserve any remaining glucose or glycogen. Simple, right? But, you know me, I like to paint the whole picture, that way you can make your own informed views. So yes, we’ll need to take a closer look at ketosis and ketones.
Let’s check out the process of ketosis process
Ketones, which are produced in the liver mitochondria cells (this process is called ketogenesis), are said to be glucose-energy sparing and prevent the breakdown of proteins The three ketones are substances called acetoacetate (acetoacetic acid), this little number is quickly converted to acetone, beta-hydroxybutyric acid (βOHB) and this one is the main KB used by the body (remember this one, we’ll be talking a lot more about it soon) and acetone (yes, as in nail polish remover). Oh, and before I forget it’s worth noting that insulin inhibits ketogenesis.
In the process of producing energy our cells make acetoacetate from another energy-related compound called acetoacetyle CoA (or acetyle coenzyme A or just CoA). Under normal conditions compounds such as acetoacetate don't accumulate in the body, and are easily metabolised by our body tissue. However, when there's a short supply of glucose the body, in it's attempts to boost energy supply, the body makes too much CoA. The result is a higher rate of production of ketones, which signals to the body that ketones are in enough supply that it can, yes 'switch', and use ketones for fuel and spare glucose. All things in balance though, that's the body's ultimate goal, so as glucose continues to be in short supply and ketones build up, and in extreme cases ketones can build-up in the blood (ketonemia) and in the urine (ketonuria), which then upsets everything, 'not happy Jan'!
How do ketones improve energy supply?
As a nutritionist who was taught ketosis was always a bad thing, I struggled at first with the thought that ketosis could be a good thing, at uni we associated ketosis with a pathophysiological condition, in diabetes, ketoacidosis. Check out Table 1 below and note, ketones in a normal diet exist in the blood at not even 1 millimol per litre (m/mol) of blood. In a ketogenic diet ketones need to be around 7 m/mols, and in ketoacidosis, at the extreme end, ketones are around 25 or higher m/mols. In ketoacidosis, the acidic change in the body is not sustainable and loss of consciousness and death can occur as time goes on, most of us have seen this in movies where a diabetic (type 1, a person whose body isn't able to make insulin) goes into a diabetic coma from not having their insulin injection. A keto diet aims to induce a mild state of ketosis in order to alter fuel selection in the body.
Ketones in our blood, on any normal day, are at a much lower level than glucose, around 0.3 (mmol/l). It’s not until they reach a concentration of 4 mmol/l (the same level as glucose) that they’ll be used to produce fuel by the cells of body in a significant way, including the brain, although the liver while it produces ketones it doesn't use them for fuel. It’s thought that the upper level of ketones recommended in a ketogenic diet is 8 mmol/l (Paoli, 2014), beyond this, things tend to become less than desirable.
Ketone bodies as energy
We’ve chatted about CoA and how it’s a compound used to create energy. Ketones are pretty efficient at creating energy. Remember βOHB? Good, βOHB produces two molecules of energy currency (acetyl CoA) which buys us fuel called ATP. So, KBs produce more energy than glucose; and hence the process of ketosis leads to more ATP. And, if this weren’t enough, glucose in the blood appears to be maintained at reasonable levels during ketosis. Seems our bodies are able to make enough glucose (up to 60% of our needs) from using glucogenic amino acids (see Table 2 below ) and from the glycerol from the breakdown of triglycerides. I have to confess, while it sounds a little challenging to find the right ‘level’, ketosis isn’t as scary as I thought it was going to be.
Here’s another interesting tid bit; our little ones produce and use ketones more readily and easily than we adults, and the elderly also appear to use ketones reasonably well too. In researching keto diets you will see discussion around the evolutionary aspect, that we have ancestrally used ketones as fuel, certainly this is born out when looking at bacterial synthesis of ketones as an indicator of evolutionary factors (Newman and Verdin, 2014).
What does a ketogenic diet look like?
Tracking down an actual agreed upon ketosis diet was a tricky task, there are a lot of views on how many carbs you should eat, and of what type, how much fat, how much protein, what foods are in, what are out. Clearly there are a few takes on a working keto diet. As I've said, I feel one of the challenges for the everyday person looking to stick to a keto diet is knowing if you are actually in ketosis or not. When you talk about levels of something in the blood you are sitting firmly in a clinical realm. In trying to emulate by rough estimate a clinical situation the many individual factors will yield enormous vulnerability and variation. What I'm saying is that in my view this is a diet best attempted with professional support, but here’s a bit of a rough guide:
Some keto diets refer to ratios of the macronutrients for example 4:1 (fat to carbs), or 3:1 and so on. 20-50g of carbohydrates a day is not a great day, consider that 100g of soba noodles is 79g of carbs, 100g of dried dates has 67g of carbs, protein powder (30%) per 100g has 65g of carbs, 100g of salted corn chips gives you 58g of carbs, an apple has about 20g and a slice of bread 15g… you get the picture.
On a keto diet you are encouraged to eat:
Charlie Foundation has a huge range of recipes: https://www.charliefoundation.org/resources-tools/resources-2/find-recipes
What does the science say?
I started out looking generally at keto diet research and was overwhelmed by the amount of studies showing positives across many areas, including longevity, weight loss, diabetes, blood lipids, appetite control, satiety, epilepsy, cancer, Alzheimer’s disease, Parkinson’s disease and more, keeping in mind many of the studies are animal-based. Let me get this straight... we are saying here that eating fat makes you lose weight? Wow! Now that is a turn around!!!
The list of benefits go on to include a decline in type two diabetes, reversing kidney damage as well as diabetic nerve damage, improved blood lipid profiles and cardiovascular outcomes. There are increasing studies, at this stage mostly animal-based, suggesting that a KD may potentiate some chemotherapies, and reduce growth of some tumors, for example glioma. One of the challenges in cancer therapies is to cut the supply of energy to the cancer cells (they use glucose), it seems that a keto diet affects the energy source for tumor cells and inhibits their growth, tumor cells aren’t able to metabolise ketones for energy, thereby improving survival rates (Woolf & Scheck, 2015).
The alternative fuel production process appears to be the key to many of the beneficial outcomes. Some have gone as far to suggest that ketones are “super fuels”. It's still early days and there are suggestion of even more benefits to this seemingly impressive fuel option called ketones, well specifically β-hydroxybutyrate. For example, ketones may to act as signals that influence the inhibition of compounds involved in disease processes at a gene transcription level (Newman & Verdin, 2014), enter epigenetics. If you're totally into the techy side of things, ketones appear to influence at least two cell receptors, and inhibit a class of compounds (HDACs) that interfere with gene expression, when allowed to party HDACs have a role in risk of cancer.
Are there any downsides?
Keto diets aren’t necessarily ideal or right for everyone. Issues range from the impact of 'dieting' or dietary restriction in terms of body dysmorphia, along with other outcomes, for example we know yo-yo diets can lead to weight gain over the long term as well as negative health outcomes. Aside from the challenge of the restriction, some report feeling heady and struggling to focus as the brain adjusts to a different fuel source, which can compound the challenge of the change. Other side-effects that might influence compliance include feeling sluggish, nausea, bad breath, constipation and altered sleep patterns.
Some studies have shown that individuals on a high fat diet, may experience increased levels of lipopolysaccharides crossing into the bloodstream. Increased levels of LPS have been linked to numerous health conditions including colon cancer.
There was some debate over discrepancies in findings of weight gain and weight loss. It appears that the composition of the macronutrients in a ketogenic diet may be at play here, specifically the percentage of protein (Newman & Verdin, 2014). In lowering both carbs and protein (in some ketogenic diets as low as 5%) this puts total fat intake at a whooping figure. Keeping in mind a high-fat diet alone doesn't seem to exhibit the same benefits as a high-fat keto diet (Newman & Verdin, 2014). A KD if your vegetarian or even more so vegan could be pretty darn tricky, and on the whole your diet could be very limited. Oh and there was some discussion of increased oxidative stress under a KD, but all in all it’s either too early or the negatives are just not there.
Making sense of it
The question it seems is how you stay in a state of ketosis? Unless you have a handy thing-a-mobob that measures your blood ketones it might be a bit hit and miss. As a nutritionist I've waged a bit of a war with my 'variety' mantra in order to see past it and look objectively at this 'diet', and on that, here at Cadence Health we are pretty none-diet. In saying that, we believe that most diets offer some benefit, whether it’s by virtue of cutting out the %*^#, or just trying new foods or ways of eating.
I have a friend who is on a self-imposed low-carb diet, he happily admits to eating two eggs and bacon for brekky each day, some cheese and tuna for lunch, and a chop for dinner. Yes, he misses many foods, mouth-watering fresh fruit for one, although he does have some fruit at times. He admits it's a low-carb diet, not a no-carb diet, and enjoys a good tipple, but he rarely eats vegetables or grains. The nutritionist in me is screaming with every fibre (no pun intended) to encourage him to eat more variety, more colour, more produce, more fibre. I worry about his vitamin C, about his antioxidant compounds, and so on. But, he is looking great and reports he feels great, and at just 50, he says he hasn’t felt this good in years, his blood cholesterol is all fine and he feels well.
So it's over to you, be informed and make a choice that works best for you. Oh and BTW, we are not funded by any organisations, this article is written from an objective and educational view point. And, seek medical advice if you’re not feeling tip top or want to have a really concerted go at a KD.
This article is not intended to replace medical advice, always seek suitably qualified support when you feel unwell or are looking to restrict your diet.
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