Recently I began a 3-day fast, which then got extended to 5 days.
The intention was to use the “Tim Ferriss method” (described here). Essentially accelerating the shift from glucose burning to fat burning as quick as possible, avoiding the negative physical feelings associated with the transition period. (60 second video primer on ketones if you’re not familiar).
However, in the process of researching more about the measurement of blood glucose and blood ketones, I realised its possible to experiment a bit.
There has been some excellent research done by Valter Longo and his colleagues at the University of Southern California on a way to do fasts, without completely stopping eating.
Essentially, they were aware of all the health benefits associated with fasting, but wanted to tackle the problem of compliance. For most people these days, the thought of not eating for 5 days is too much to handle.
They have come up with a 5 day diet that is low enough in calories and carbohydrates, that the user gets the vast majority of the benefits from fasting.
Actually, they have patented their specific diet as prolonfmd.com – and are selling it to hospitals to prescribe to their patients. Your first thought is probably…huh? But its more about “playing the game”, and finding ways to get fasting into hospitals, than it is about money. I believe Valter has even gone as far as to pledge his profits from the endeavour to charity. For more on Valter Longo and the FMD diet – check out Rhonda Patrick’s podcast with him.
Luckily for us, we can use Valter’s research into fasting, without getting a prescription for his diet. In the paper that they published to cell.com, they describe the details of the diet:
The human FMD diet consists of a 5 day regimen:
– Day 1 of the diet supplies 1,090 kcal (10% protein, 56% fat, 34% carbohydrate)
– Days 2–5 are identical in formulation and provide 725 kcal (9% protein, 44% fat, 47% carbohydrate).
Damien, of Quantified Body figured out that this is similar to the macronutrient composition of avocados. So for example, you could have 2 medium sized avocados per day on each of the 5 days.
It doesn’t have to be avocados though, it could be anything that fits the above macros.
The other interesting piece of the puzzle, that contributed to this fast, was a paper by Dr Seyfried on treating brain cancer.
They found that if they could keep patients in what they termed “nutritional ketosis”, then they could achieve remission in some patients. Nutritional ketosis differs from simply measuring blood ketone levels, instead it measures the ratio between blood glucose and blood ketones. I’ve written in more detail here about it.
My 5 Day Fast Details
The crux of my experiment, is that adding in some calories/nutrition makes the whole process MUCH easier. And you can do it in a calculated way.
Here’s the rough breakdown of what I consumed:
- Day 1 (after 24h) – 2 tablespoons of MCT oil (C8)
- Day 2 – 2 tablespoons of MCT oil (C8) + 1 tablespoon of coconut oil
- Day 3 – 1 avocado (with Himalayan sea salt + apple cider vinegar) + 1 tablespoon of coconut oil
- Day 4 – 2 avocados (again with Himalayan sea and apple cider vinegar) + 1 tablespoon of coconut oil + 1 tablespoon of MCT oil (C8)
- Day 5 – Nothing until I broke the fast in the evening
You can see I didn’t adhere strictly to the fast mimicking diet, and was generally under the prescribed amount of calories. But was far in excess of a simple water fast.
From the end of day 1, my ketones were elevated (no doubt helped by the MCT oil). Highest they reached was about 4.4mmol/L, with blood glucose simultaneously at 2.8mmol/L.
The measurement of blood ketones and blood glucose come in useful for 3 main things: