One More Thing On Fasting
Fasting and obesity
For people that are overweight or obese, fasting is beneficial not only because they lose weight due to overall reduced calorie consumption, but their body’s defence systems get a chance to get turned on, the cleanup of cells, insulin sensitivity is improved and glucose levels come down. However, due to the poor metabolic condition many obese individuals are in, fasting supervised by a medical practitioner is highly recommended.
But what’s more interesting is that patients with certain diseases like type 1 diabetes, multiple sclerosis and cancer benefit from fasting. An especially potent combination is chemotherapy with fasting. When you mimic fasting with something like metformin which is often prescribed to patients with prostate cancer or combine it with actual fasting it helps beat the disease. Even macular degeneration (loss in the centre of the field of vision) has been shown to be slowed or even reversed by fasting.
How much is too much?
Let’s leave the different lengths and types of fasting for the next article. For now let’s just say that every time you spend some time without a caloric intake (even overnight) or reduce it significantly, the body to some degree triggers various protective processes that benefit your lifespan.
Doing a daily 16-hour fast does wonders for fat loss and mental resilience. A 24-hour fast would give your gut some extra rest and show some signs of increased autophagy, however, Dr Peter Attia says three days is probably the minimum to hit some of the physiologic benchmarks of fasting such as glycogen depletion, significant reduction of glucose and insulin that triggers autophagy and the inhibition of senescent cells, inhibition of mTOR and activation of AMPK.
After the three day mark, the autophagy almost kicks into a higher gear or so-called chaperone-mediated autophagy or the deep cleanse.
Even if you are fanatical about fasting and take periods of extended hunger very well, you don’t want to practice multi-day fasts too often or for too long and cause other damage including muscle loss. This is a stressor for the body and it is only beneficial if it’s in controlled doses. Probably 3-7 day fasts no more than four to six times per year are best. I personally aim to do a three day fast twice a year. Make sure you always play it by ear, start with shorter windows without food and look deeper into it before committing. We are all different and need an individual approach. If in doubt consult a physician before undertaking a fast longer than 24 hours.
“There can always be too much of a good thing. The point of diminishing returns has to be found for every person individually, however occasional 3-7 day fasts show the strongest results for most people. This might not be practical or even safe for some so often a version of daily or weekly caloric restriction protocol is more sustainable.”
Glucose during prolonged fasts
People mistakenly think that after 72 hours or more of consuming water only the body is completely depleted of glucose and the body runs on ketones only. Not the case.
After three days or so, the body’s glucose levels reach the new equilibrium and stop being so erratic. This flat line of glucose would rest around 3 mmol (high 50 mg/dL) and the only thing that can make it budge is exercise. Lifting weights would increase it by about 1 mmol (20 mg/dL) and then come back down slowly says Dr Peter Attia.
In a clinical trial by George Cahill, the patients consumed only water for 40 days and even at the end of the trial still maintained 3 mmol of blood glucose. How is that possible?
Your body is breaking down triglycerides into free fatty acids which are then used to make the ketones (the body’s main source of energy when there is not enough glucose). The backbone of that free fatty acid is glycerol which the liver uses to make glucose. Even a month into a fast, as much as 40-50% of the energy going to the brain of those subjects was still coming from glucose even though they weren’t consuming anything but water.
Refeeding
Breaking the fast is just as important as the fast itself. You have to make sure your nutrient intake is sufficient and of good quality, the otherwise caloric restriction will do more harm than good. What to eat is beyond the scope of this article, but generally, it is assumed that you can eat ad libitum (as much as you want) in your feeding window. Just make sure you are eating in a peaceful setting, mindfully, slowly and only until 80% full.
When refeeding on a daily caloric restriction protocol (i.e. fasting daily for 16 hours and eating for 8) it is important to stay away from big insulin-spiking foods such as white carbs, sugar and fruit. Glucose spikes will, along with giving you type 2 diabetes and cardiovascular disease, also cause glycation (stickiness of sugar to cells preventing them to work properly) and inflammation, and switch off the defensive mechanisms against disease and ageing.
Stick to high-quality protein sources, healthy fats and heaps of fresh vegetables.
Cyclic periods of prolonged fasts, intermittent fasting and occasional feasting are all important. Even days of constant snacking can be ok occasionally. The more you switch it up the more you keep your metabolism on your toes. Staying too long in one state can be harmful. A prolonged state of CR can cause muscle loss, micronutirent depletion, and hormonal imbalances, while extended periods of growth with increased IGF-1 is directly correlated with higher incidents of cancer. If all cells grow, so do cancer cells.
Kids and feeding practices
What we teach kids today is they should never go hungry. We say here is your breakfast, snack, lunch, dinner, supper, and all the candy in between. Go to bed full, wake up and eat some more. And that’s not even taking into account the poor quality of food we offer them.
The current obesity epidemic is not an issue only in making these kids overweight and completely metabolically inflexible (unable to use the excess calories on their bodies). But we are shutting off their survival genes when programing their epigenome for a feast, not famine exposing them to all the pitfalls of ageing. Their bodies are ageing quicker than they otherwise would. In the next 30-40 years we will see a dramatic increase in all-cause mortality because their clock has been accelerated.
This doesn’t mean kids should undergo the same fasting principles as for adults. But managing the quality and quantity along with the timing of food intake is crucial for their long term health and wellbeing.
Conclusion
Over millions of years, humans have evolved to survive various states of adversity. This is how we are programmed to thrive, become more resilient, have a sharper mind, better body composition and have more sex drive. The ultra-comfortable lifestyle that we have surrounded ourselves with is not doing us any favours. Find occasional states of discomfort and deprivation for yourself. Find ways to get occasionally hungry, your body will be deeply grateful.
Resources and further reading and listening:
https://www.youtube.com/watch?v=dhjZcFbKFdM
https://www.youtube.com/watch?v=9tRohh0gErM
https://www.youtube.com/watch?v=wD8reCw3Kls&t=732s