Recently there has been a lot of talk about short-term fasting for weight loss. More specifically, intermittent fasting, when you eat your daily calories in a compressed period of time in one day. An 18:6 means you eat for 6 hours and fast for 18 hours. A 20:4 means you eat for 4 hours and fast for 20 hours. There are other variations, like alternate day fasts but the key is to find one that suits you. When the bulk of your fasting takes place while you sleep, it is easier to build into your life.

Personal Experience

I find the 18:6 fits well with my lifestyle. I start eating at 12 mid-day and finish at 6pm. I usually do it Monday to Wednesday. You can drink water, tea, coffee and herbal teas during the fast period without adding sugar or milk. I am in maintenance now as you all will be, when you finish the weight-loss phase.  I usually allow myself to eat when and what I fancy over the weekend, then do an 18:6 Monday to Wednesday. I tried a 3 day fast once, just to see how it felt. Religious fasts/pilgrims mention feelings of euphoria. I definitely did not feel that, I hated it and would not recommend it. The rebound to eating more food than normal, when you come off a 3 day + fast, leads to weight-gain. In addition, hunger is a stressor and we know that the stress hormone cortisol, increases blood sugars and fats which we want to avoid.


So what are the Benefits?

Fasting turns on autophagy. In this process the body starts a good clean-up of damaged cells and old fragments of viruses and bacteria, helping to eliminate them. The liver appears to benefit the most. As we age and our body is not as regenerative as it used to be, fasting can help. It may protect us from degenerative diseases. 

For weight-loss, it is brilliant in my experience and clients report the same. It helps to reduce cravings as you adapt to fasting. Give yourself time to adapt to it. We often eat out of habit or boredom rather than hunger. When you are not eating, your body is using its own stored fuel (your fat cells). We burn calories when we sleep (our Basel metabolic rate) and even more when we move.

Christiaan Leeuwenburgh, Professor & Chief, Division of Biology of Aging at the University of Florida has studied this for years and he is worth a listen to. Here is a good short You Tube video explaining autophagy


So How Long do we fast?

What I was curious about is how we know when autophagy is turned on in our bodies or how long we need to fast to experience autophagy. Are there markers in bloods that tell you the clean-up has started? Yes, there are markers but it is a complicated area and I was looking for the short answer. Having read around the subject, a fast of 16 hours + starts off the process. Practically, 16 hours is achievable and 18 hours is even better. I am recommending the 18:6,  fast for 18 hours and eat within a 6 hour window in one day.

I deliver a presentation to clients about inflammation, oxidative stress and in these presentations, I highlight the foods that provide you with protective nutrients – flavonoids, carotenoids, Vitamin A,C,E.  Eating these and fasting 18:6 is a double whammy protection. I also include recipes like the cacao breakfast shake, colourful salads, berries so that you are eating these antioxidant protective nutrients. 


It’s never just one thing, is it?

Good sleep, stress reduction, exercise and dietary antioxidants all promote autophagy combined with a reduction in calories. I promote herbal teas at night. I suggest not eating late, this helps better sleep. I encourage exercise after week 3 of the programme as most people have mastered food by then. I encourage venturing out into nature for walks, cycles and good chats. All of these factors are as important as fasting. 

This is a lifestyle change and it is multi-faceted. If we try to change everything at once, it can be just too much, so start small. The same applies to fasting. Try one day of fasting for 18 hours then try it again next week. See how you feel after it. Allow your mind and body to adapt. If it does not suit you, that is fine. You are doing enough.

Note: This article only applies to clients where I have taken a medication and health history. Fasting may not suit some people on medication.

For those who like science, there are 2 proteins that control autophagy –

  1.  Target of Rapamycin (mTOR) 
  2. Adenosine 5’-monophosphate-activated kinase (AMPK).

 mTOR is activated by you eating (growth signals, insulin and nutrients) and inhibits autophagy. AMPK senses low levels of energy (you fasting for 18 to 20 hours) and inhibits mTOR which leads to an increased activation of autophagy  There is another protein called LC3-II, and the presence of this protein confirms autophagy is taking place. P62 is another marker that can be assessed to see if autophagy is increasing or decreasing

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