I get regular questions about fasting, from people trying to
lose weight, cleanse their bodies, or just learn more about ‘alternative’
practices. It’s sometimes a tough question, as fasting is a practice associated
with both life-changing healing experiences as well as horror stories, and so
there are some strong opinions out there. Additionally, fasting has a long
association with religious practices – monks, shamans and lay people the world
over have fasted for spiritual reasons since recorded history began. Finally,
it’s Ramadan, the Muslim month of fasting, so this week, I’ve opted to give my
thoughts on fasting.
Let me start by saying that there is not a lot of research
on fasting in humans – the little I have been able to turn up focuses on the
performance of athletes observing Ramadan, and a few lab studies on how fasting
affects gene expression. There is evidence that caloric restriction does increase lifespan among a wide variety of animals, but there are questions as to whether this would apply to humans as well. The most interesting research I
came across was a group of studies that indicate that fasting induces production
of a group of proteins called sirtuins, which have been characterized as
‘anti-aging’ proteins, and have the effect of increasing alertness and energy
efficiency. From an evolutionary perspective, it appears that these proteins
were induced during periods of famine, increasing our ancestors’ likelihood of finding
food and surviving to pass their genes on. They have recently become major
targets for commercial ‘anti-aging’ products.
So in the absence of a large body of research, here are some
basic ideas on fasting, based on clinical experience and sound judgment.
First of all, let me say that I am not in favor of drastic
fasting, like multi-day water fasts, multi-day juice fasts, or the perennially
popular Master Cleanse. I don’t see benefit in depriving oneself of all
calories for substantial periods of time, and I especially don’t see benefit in
consuming sugary drinks at the expense of nutrients. It’s my belief that juices
and the Master Cleanse, because they lack the mollifying effect of fiber and
protein, subject your body to the stress of a blood sugar roller coaster,
without much benefit. One of the benefits of fasting is giving the body a bit
of a ‘metabolic break’, and drinking juice causes unhealthy spikes and valleys
in blood sugar levels.
That said, I do believe that fasting can be healthy. Here
are some essential components of healthy fasting: avoidance of unhealthy foods,
mild caloric restriction to induce sirtuin proteins, reduced activity levels so
as not to stress the body, short duration to prevent negative outcomes, and
easily digestible foods consumed to break the fast.
Before I cite specific fasting practices, let me say that I
think our bodies are more complex than we understand, and that practices that
have a long cultural history are worthy of our attention. Our scientific minds
have limited understanding, and can sometimes lead us astray – low-carb dieting
is a good example – and I believe that long-standing cultural practices have
survived because they work. This is why I recommend the Mediterranean diet over
low fat diets.
I find two main healthy examples of intermittent fasting, or
periods of lean eating, in our cultural history. The traditions of both Lent
and Ramadan are associated with forms of fasting, which I believe may have more
beneficial health effects than our modern aggressive forms.
Fasting during Lent has taken many forms in the past,
including daytime fasting with evening breakfasts and abstinence from animal
products. Certainly, the abstinence from animal products for substantial
periods of time has beneficial health effects, as it provides a respite from
significant sources of saturated fat and cholesterol in the diet. In our modern
time, Lent has been associated with abstinence from meat on Fridays, a theme
that I believe can be converted into a plan for weekly fasting – caloric
restriction once a week for a set period of time satisfies the criteria I
mentioned previously for a healthy fast, and I think that we may do well to
embrace this form of fasting.
Daytime fasting, followed by breaking of fasts with
balanced, easily digestible meals is also worthy of our attention. I’d posit
that this method of fasting is effective at inducing sirtuin proteins while
also providing adequate nutrition. While this method of fasting is practiced daily
for long periods of time in Ramadan, and was practiced for long periods of time
in older Lenten traditions, I don’t think that it needs to be practiced for
long periods to be effective. Fasting once a week on occasion may be similarly
effective. Most important, I think is that the meal that breaks the fast be
easily digestible and provide a balance of protein, fat, and carbohydrates,
along with a range of vitamins and minerals.
Several years ago, I learned of the Moroccan practice of
eating harira to break the Ramadan fast, and was really inspired. Harira is a soup consisting of lentils, chickpeas, tomatoes, onions, rice, olive oil, a small amount of meat or broth, and a rich array of herbs and spices. This meal provides
a good balance of protein, carbohydrates and unsaturated fat, and is rendered
extremely easily digestible by a combination of long-cooking and the use of
spices that aid digestion and assimilation, such as ginger, pepper and
coriander. When it comes to easily digestible foods after a period of fasting, I
think harira may have it nailed.
And finally, one important oversight that I see people make
consistently is that they don’t give themselves a break while fasting, and just
keep at their normal activities. Sometimes this is difficult to avoid, but I
think it’s important to give our bodies a break while we are depriving them of
calories – maintaining a high level of activities on a low amount of calories
stresses the body physiologically, which I think is less than healthy.
My final message today is a restatement of the important
components of a fast: avoid unhealthy food, mildly restrict calories, take it
easy, keep it short, and eat gently to break the fast. Above all, keep it sane –
crashing your system is the opposite of what a fast should achieve.
