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What is the keto diet?

Rachel Lett, RNutr.

Chief Care Officer

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Hey there 👋 Did you know that in order to survive, our cells need a constant supply of energy? Thankfully, our clever, hybrid bodies can use either glucose (by-product of carbohydrates), or fatty acids and ketones(by-product of fat) to fuel cells.

My colleague Adam is a medical doctor and last week, he wrote about how you can take control of type 2 diabetes by using ketones for energy.

Today, I want to tell you the story behind this ability that we share with all mammals and how to benefit from it.

Once upon a time 📖

For our ancestors, during times of starvation, fasting, or when carbohydrates were limited, this design was crucial for survival. Under these circumstances, their body would shift into ketosis, whereby fat is the primary fuel source.

However, unlike them, this ‘switch’ is now relatively dormant as we rarely metabolise fat for energy — these days, carbohydrates are plentiful, and we have around the clock access to food.

Additionally, society is encouraged to eat a low-fat, high-carbohydrate diet, based on the eatwell plate; which was established on the premises of skewed science.

Dietary recommendations have been based on the hypothesis from Ancel Keys that high-fat diets caused cardiovascular diseases and reinforced by economic interest from food industries — not significant, evidence-based science.

In recent times, nutrition science has revoked many of these accepted nutrition guidelines, and is leading the way in what we should eat.

Saturated fat is back on the menu as more and more evidence suggests that ketosis (blood βHB ketone level > 0.5 mmol/l) is protective against many chronic diseases and can reverse insulin resistance in type 2 diabetes.

Good news! You don’t have to starve 😀

You can reap the benefits of ketosis, without having to endure starvation. Through nutritional ketosis, we can effectively switch from being a ‘sugar burner’, to a ‘fat burner’.

This is achieved by increasing dietary fat, reducing carbohydrate consumption and eating adequate protein for our body’s needs.

That way, you’re getting the necessary macronutrients to feel satiated while sending a hormonal signal that will get you into nutritional ketosis.

As part of our therapies at Span, we leverage nutritional ketosis as a powerful tool to reverse insulin resistance for patients with type 2 diabetes.

To whet your appetite, here are a few health benefits you can expect from it:

  • Increased insulin sensitivity
  • Improved cognitive function & mental clarity — no more brain fog
  • Increased energy
  • Reduced hunger and cravings
  • Weight loss (without deprivation)
  • Reduced inflammation
  • Improved biomarkers — blood glucose levels, cholesterol, triglycerides

What happens when you transition? 🤔

Nutritional ketosis mimics fasting, in the sense that it switches from one fuel source to another.

To better understand these metabolic changes, let’s run through the physiological transition from glucose to fat metabolism.

Firstly, energy is cleaved from stored glucose (glycogen) in muscle and liver tissue (where we store about 2,000 calories worth).

After about 18–24 hours, once glycogen stores have been depleted, our bodies make glucose through a process called gluconeogenesis — this suggests that we do not need to consume carbohydrates, because we’re very efficient at making our own glucose!

However, gluconeogenesis alone can’t produce enough energy to support our powerful brains; so finally, we switch to ketone bodies— fat-burning mode, ketosis! 🔥

During ketosis, our stored or dietary fat is metabolised into fatty acids and ketones, which are used to power our muscles, organs and the brain.

Remarkably, we store approximately 100,000 calories of fat, so there’s no need to panic next time you hear your tummy growl!

How does your body respond? 🚶‍

Adapting into an efficient ‘fat burner’ takes time, and with it, you may experience some adverse side effects. Remember, these are only temporary and can be prevented or mitigated.

Set your sights on the ultimate, lifelong goal — to improve health and reverse the cause of your type 2 diabetes.

The severity of symptoms will depend on your previous diet, or how quickly you delve into nutritional ketosis. It will be easier to weather the storm if you expect to feel poorly for a few days, and equip yourself with some remedies to counteract symptoms.

Within the first few days of nutritional ketosis, your body will go through some predictable, physiological changes, that are completely normal.

As you reduce carbohydrate intake, insulin levels drop and glucagon levels rise. Working in tandem, these hormones signal the body to cleave energy from glycogen, as well as up-regulating the kidneys to excrete water and minerals (like potassium, magnesium and sodium).

Moreover, water is lost through the metabolism of glycogen as every gram is packaged in 3 grams of water.

As a result, you may experience frequent urination, dehydration, and loss of electrolytes, which may accompany other symptoms like dry mouth, thirst, constipation, muscle cramps, heart palpitations, nausea, brain fog, fatigue, headache, and rapid weight loss in the form of ‘water weight’.

These symptoms can be managed by carefully replenishing fluids and electrolytes.

Here are a few things you can do to help:

  • drink plenty of water 💧
  • sip on bone broth 🍵 throughout the day (replace fluids and electrolytes)
  • up your sea salt intake and season food liberally
  • eat foods that are good sources of magnesium and potassium, like nuts, fish, avocado, broccoli, cabbage and green leafy vegetables

Additionally, make sure to eat plenty of green leafy vegetables and brassicas (like broccoli, cauliflower and cabbage) to maintain fiber intake and keep constipation at bay.

If you experience hypoglycemia, your diet and medication may need to be adjusted — contact your GP straight away.

As you withdraw from carbohydrates, your body will often respond with hunger and cravings — try to stick with it, and break the cycle as a sugar burner. Eat plenty of high-fat food to suppress hunger, and drink fizzy water with a squeeze of lemon 🍋to subdue sugar cravings.

Please, don’t feel overwhelmed or disheartened by the list of temporary side effects. These are all possible symptoms, which you may, or may notexperience. In any case, it’s important to bear in mind that they will be short-lived, and your health will be richly rewarded.

If you need support or guidance, remember that your dedicated, friendly Span team are always here to help, so don’t hesitate to contact us.

Look out for our next post where we’ll be discussing macronutrient ratios — be prepared for a diet filled with delicious fats!

Ready to jump into nutritional ketosis? 🤩

Next week, I’ll be explaining in details the steps you can take to retrain your metabolism and experience the wonderful benefits of this state.

If you’re interested in joining Span, download our mobile app on www.span.healthor contact us at to learn more.

Stay tuned 🙌🏽

I’m sure you’re curious about the science behind all this 🔬 Here are some recent medical publications about this topic:

  • The effect of insulin on renal handling of sodium, potassium, calcium, and phosphate in man. …J Clin Invest. 1975 Apr;55(4):845-55. Research Support, U.S. Gov't, P.H.S.
  • Dietary carbohydrate restriction as the first approach in diabetes management: Critical review and…The inability of current recommendations to control the epidemic of diabetes, the specific failure of the prevailing
  • Do ketogenic diets really suppress appetite? A systematic review and meta-analysis. - PubMed - NCBI Obes Rev. 2015 Jan;16(1):64-76. doi: 10.1111/obr.12230. Epub 2014 Nov 17. Meta-Analysis; Research Support, Non-U.S…
  • Metabolic Effects of the Very-Low-Carbohydrate Diets: Misunderstood "Villains" of Human Metabolism During very low carbohydrate intake, the regulated and controlled production of ketone bodies causes a harmless
  • Beyond weight loss: a review of the therapeutic uses of very-low-carbohydrate (ketogenic) diets Very-low-carbohydrate diets or ketogenic diets have been in use since the 1920s as a therapy for epilepsy and can, in
  • Insulin and the kidney. - PubMed - NCBI Nephron. 1975;15(3-5):306-26. Research Support, U.S. Gov't, P.H.S.; Review
  • Effects of different dietary approaches on inflammatory markers in patients with metabolic… Nutrition. 2016 Mar;32(3):338-48. doi: 10.1016/j.nut.2015.09.010. Epub 2015 Oct 28. Meta-Analysis; Research Support…

Additionally, a couple of interesting books:

Kalamian M. Keto For Cancer, Ketogenic Metabolic Therapy As A Targeted Nutritional Strategy. 1st ed. Vermont: Chelsea Green Publishing; 2017

Mercola D. Fat For Fuel. 1st ed. Hay House INC; 2017

Perlmutter D. Grain Brain. 1st ed. London: Yellow Kite; 2014

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