Does the time window we choose to fast matter?

"Hi, Gary, curious to pick your brain about fasting windows":

"But, importantly, the time window we choose to fast matters. Fasting in the evening and overnight, then eating early in the day is the pattern that has the most profound benefits. The research is clear that people who eat in the morning and afternoon have healthier blood lipid profiles and better blood sugar control and tend to weigh less than those who eat late in the day. And people who eat breakfast tend to have better overall nutrient intakes than those who skip it. Also, eating during the waking hours, when your mental and physical demands are highest, gives you the fuel to perform at your best."

https://www.washingtonpost.com/lifestyle/wellness/many-intermittent-fasters-skip-breakfast-heres-why-thats-not-a-good-idea

Gary replies:

The person asking about intermittent fasting is best described as an extreme adventurer. He is preparing for an immense adventure that is going to test him to his limits and more. For longer than a month, he will exercise day and night to exhaustion, often in extreme stormy conditions. He has to take with him everything he requires. He will be alone and there will be no stops for refreshments along the way. He is not ready to announce his plans so I will say no more about what the expedition will be, other than to say that it is life threatening even for the most prepared adventurer. He requires extreme fitness. Strength, endurance and general all-round physical and mental hardness are what he must possess.

Intermittent fasting has been a topic of advice and discussion. The article in question is about fasting for weight loss and for improving one's health profile. Our adventurer's needs differ. He must not lose weight; he must begin his expedition with a reasonable layer of fat, which will be a source of energy and also insulation from the cold. What he must concentrate on is turning himself into an efficient fat-burning machine. My experience tells me it takes several months to become an efficient fat burner, so he must start now: eating low carbohydrate during the day while pushing his limits of strength and endurance. Adopting a low carbohydrate way of eating for most of the day, especially when exercising is the way to go.

Unless he must lose fat weight, a low-carbohydrate diet must be energy neutral - not energy deficient. Our adventurer needs to do enormous amounts of exercise while being low carbohydrate but still energy neutral. This means cutting out foods such as rice, bread, sugar, milk, soft drinks and juice, while increasing the intake of foods that contain lots of fat and oil and quite low in carbs, such as coconut and olive oil, cream, salads, nuts, beans, eggs, fish and meat. This is actually quite easy to do because food that is high in fat and oil is very high in energy (energy dense), so it does not take much to offset the energy burned during extreme exercise. Unlike carbohydrate-based foods, the food being emphasised is high in nutrients, such as the fat-soluble vitamins. The fat-soluble vitamins are immune-boosting, which has to be a good thing during these COVID times!

Something to be aware of: excessive protein may be counterproductive, since the excess protein may end up being converted into carbohydrate.

Our adventurer must be practical. He has a family. He has children. If he is fasting during the latter part of the day, he will not be sitting at the table sharing and enjoying the evening meal with the family. There are already too many things interfering with family life nowadays, and I do not want to add another by asking to skip eating with the family. It is more practical to do any special diets during the day, while also doing the bulk of his training, then enjoy a delicious meal with his loved ones. This can include carbohydrates - even pudding; but only if he eats his vegetables! Come morning, the carbs are off the menu again until evening. I call this the "Gentle Keto Diet". You can read more about this topic here: Gentle Ketosis - some helpful guidelines