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Nutritional Science Series 11: Keto Fasting

Intermittent fasting is a practice that often accompanies ketogenic protocols as it a mechanism to increase ketone production and support fat loss. As the name implies, intermittent fasting is where one abstains from eating for varying periods of time. This may sound obscure against a doctrine of reference where we have learnt to eat at least 3 square meals a day and have frequently been told the maxim of ‘Breakfast is the most important meal of the day.’

Over the course of our nutritional science series, we have now learnt that any consumption of food results in a metabolic response in our body to convert the foods to ‘usable’ energy. When we ingest carbohydrates (and in some instances excess protein), insulin-release is a resultant response. In instances where there is excess energy (glycogen) available, the function of insulin is to advise the body to store this energy as fat for later use– a profoundly intricate and clever ancestral bodily mechanism to protect humans against periods of famine. The challenge is however, that times have rapidly changed since our ancestors were hunting and gathering for food and times of famine are very rare for us in the 21st Century.

To add to this, many of us ‘over consume’ against our body’s real energy requirements- with the result that we have excess energy in our systems that is then converted to fat deposits. When this happens, the role of insulin is to protect the fat in the fat deposits and it essentially ‘turns off’ the body’s ability to access it for fuel. For many of us, this is where our challenge lies in terms of the body being ‘stuck’ in a cycle of not being able to access fat stores, with the result that our body composition, is not optimal and we ‘pick up weight.’

A ketogenic lifestyle is one way in which we have now seen how fat metabolism can be increased. Once you are keto adapted, intermittent fasting is another way to expedite ketone production as fasting lowers insulin levels to increase fat burning. The longer the time we reduce energy intake, the more time the body has to activate energy use from fat stores.

Eating windows

There are many different protocols to fasting and it is important that you find one that fits and works for your body– this can be tested by how you feel or by self-quantification measures of monitoring your glucose levels and ketone production (purchase a ketone/ glucose meter from Made To Thrive). Either way, the protocol is to implement a fasting period followed by a feeding window. This window period of caloric consumption can vary but it is very important that irrespective of the eating window, the caloric value that is consumed, is the same and it goes without saying, that the food consumption, is within the keto macronutrient profile (high fat, less than 50grams of carbohydrate per day).

The longer you can fast for, the more beneficial for your body and the quicker the time your body will take to get into ketosis.

Types of fasting

My colleague, Dr Jockers, lists a number of popular fasting options. Whichever one you select, it is important to assess an application of how fasting may fit into your schedule and family engagements- if you are unsure as to which one to follow, be sure to consult a practitioner:

  • Near-24 hour fast: electing to eat once a day (often at night time) and conducting a water/ coffee fast in between. This is often referred to as OMAD fasting (one meal a day)
  • 4-hour window fast: The first meal of the day is enjoyed at 15h00 and the last meal of the day is finished by 19h00
  • 8-hour window: A fast in the morning with the first ‘breaking’ for a meal at 12h00 noon and the second meal is finished by latest 20h00
  • Alternate Day Fasting is another fasting regime where no food is consumed for 24 hours every alternate day

As you can see, there are many different fasting protocols that can be applied. Either way, the consumption of water to remain hydrated is primary in any fasting application.

Selecting the best fasting approach is all dependent on you and what you feel is manageable and possible for your lifestyle- as well as how your body responds. Contact us if you would like to book a keto consultation or if you would like to quantify your keto and fasting progress by measuring your ketones. Made To Thrive stocks and distributes blood ketone meters for you to monitor your success. Get in touch if you would like to purchase a unit.

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