Recently I wrote a post about cleanses and detox diets that had this comment:
You say that skipping a meal occasionally, juicing for a few days or fasting for a day is beneficial..says who? Do you have evidence of that?
That was from Heather Carey.
Okay, so here goes.
But of course, I’ll start with a disclaimer: I’m not a doctor! Nothing I say constitutes medical advice. Nothing I’m going to write should be interpreted as a specific diet recommendation, just condensed info to allow you to think about your health in a meaningful way.
Starvation and Health: Connecting the Dots
All living organisms are equipped to survive in periods of stress. Maybe long periods of time. The basic mechanisms of biological survival are very well conserved, and many of the pathways involved in energy utilization, aging, and cellular degradation have a high degree of similarity throughout the biological kingdom. Not just in primates, but in mice, flies, yeast, and in some cases even bacteria. For example it’s estimated that insulin (the chemical primarily responsible for storing energy) is at least 1 billion years old.
One of the best established facts in medical literature is that dietary restriction (reducing calories by about 20-40%) promotes longevity and reduces your chances of cancer, diabetes, and most other forms of the metabolic syndrome. This has been known for about 30-40 years and has broadly proven to be true in all organisms it’s been tested on, including humans.
When your body is put under physiological stress it’s forced to recycle old proteins into new ones, eat up organelles that are no longer serving any purpose, and reduce the hormones that make your cells want to grow.
In science literature this effect is called autophagy, and it’s probably an irreplaceable component of good health. All these effects are the same reason exercise is good for you too, but it’s counter-intuitive to think that our eating habits can trigger the same sorts of effects since “Three meals a day” has been beaten into our heads since birth.
Life Used to Be Random
Most of the volatility our instincts have been conditioned towards have been sucked out of everyday life, for better or worse. Our body’s mechanisms for energy conservation were formed when food availability couldn’t be taken for granted, and we simultaneously had to make our energy last us as long as possible but still be ready on a moment’s notice in case something dangerous happened.
Eating and exercise were non-linear, fractal, and difficult to forecast. Not anymore.
The Forgotten Fuel
The human body can live up to 40 days without food. Your muscles store enough glucose to last about 2 days.
When your body senses that food is scarce it begin turning your fat tissue into a compound called beta hydroxybutyrate (BHOB). Utilizing BHOB for fuel used to be thought of as a bad thing since the only time people seemed to use it was when diabetics went into ketoacidosis, which happens when your body can’t produce enough insulin so it can’t stop secreting glucagon, which causes your body to inject ketone bodies into the blood, which makes it more acidic. Drastic changes in your body’s acidity level aren’t good, so BHOB was thought of as a toxin.
However, that’s an extreme case that happens due to disregulation. Under normal conditions of scarcity utilization of BHOB is normal and healthy. In many ways it’s more efficient than glucose since it gets turned into ATP more efficiently and your heart in particular has an affinity for BHOB as a fuel source.
Alzheimers and dementia are beginning to be seen as “type 3 diabetes,” and it appears that brains that are overfed on glucose lose their ability to respond to insulin. In fact one of the most foolproof ways to treat alzheimers to make the brain more “ketogenic” so it can split its fuel consumption between glucose and BHOB.
BHOB is the fuel source of starvation.
Fasting and Starvation is Good for Cancer
Anyone who’s experienced a loved one that has cancer knows that chemotherapy can be just as dangerous as the disease itself. Chemotherapy drugs by their very nature are toxic and it’s hard to make sure they only treat the cancer cells.
Valter Longo is a scientist at UC Davis who showed mice with a wide variety of cancers respond much better to chemotherapy (ie, the good cells don’t go with the bad) if they’ve been starved for 2-3 days before undergoing treatment.
This “starvation priming” effect has been replicated in the other animals we usually do tests on (nematodes, fruit flies, c. elegans), and the effects have all been the same. In fact, one study found that the survival rate for “good” cells improved over 1000x with a little bit of starvation!
These sorts of treatments are beginning to get rolled out on humans and so far the results are promising.
Humans Have Been Fasting for 1000’s of Years
Every religion that I know of has some sort of ritualistic fast that requires its members to deliberately do without various types of food. They all differ in their flavor, but all center around a few common principles.
Basically they replicate the non-linearity and randomness of food consumption that’s so important to our health but hard to come about in our day-to-day lives.
I believe in the horror stories about people who try and “binge” diet and things go totally awry. I’m inclined to believe they get half the story wrong, not all of it. A little bit of timely deprivation can do the body a lot of good, but it’s what they eat afterwards that messes everything up.
What’s The “Right” Amount for This Sort of Thing?
So far this article is about 1000 words strong with me yapping about the various benefits of deprivation and that leads to the natural question:
How much should I do this for myself, if at all?
The important point here is that the benefits are non-linear. This means the most important ones occur occur in the early phases of the process, not at the end. It’s the flipping of the switch that’s useful, not the days and days of struggle afterward. Benefits usually taper off after a few days and it eventually becomes harmful if it goes on for too long.
A little bit of deprivation does the body a lot of good, but too much will make you weak.
In most studies the fasting will happen for 2-3 days, but that doesn’t mean that’s the “right” amount of time for everyone. There is no one size fits all for this sort of thing, just best to do what feels comfortable (but not too comfortable!) for you.
Personally, I just try and mindfully skip a meal from time to time and/or plan a few days when I’ll have a nice breakfast and refrain from food until after sunset.