The Power of Intermittent Fasting
If you're
already off to a good start on a healthy fitness plan, and you're looking for
ways to take it to the next level, then you might want to consider intermittent
fasting. In essence this fitness-enhancing strategy looks at the timing of
meals, as opposed to those fad plans where you eat just one or two things for
several days in a row.
On
intermittent fasting, the longest time you'll ever abstain from food is 36
hours, although 14-18 hours is more common. You can also opt to simply delay
eating. For example, skipping breakfast may be just the thing to get
you off a plateau in your fitness routine. The issue of fasting is a major
shift from my typical recommendations. I've not been a major advocate for it in
the past, but as many of you who have been reading this site for years know, I
am always learning.
To that
end, I've now revised my personal eating schedule to eliminate breakfast and
restrict the time I eat food to a period of about six to seven hours each day,
which is typically from noon to 6 or 7 pm.
Our
Ancestors Rarely Had Access to Food 24/7
So it
makes sense that our genes are optimized for to this type of feeding schedule.
It takes about six to eight hours for your body to metabolize your glycogen
stores and after that you actually start to shift to burning fat. However if
you are replenishing your glycogen by eating every few hours, you make it far
more difficult for your body to actually use your fat stores as fuel.
On the
days that I exercise in the morning, I will have two scoops of Pure Power
Protein about 30 minutes after the workout to provide nutrients, especially
leucine, for muscle growth and repair. Interestingly, since adopting this
approach for the past few months I have lost two inches from my waist size and
gained three pounds, which means I have lost body fat and gained muscle mass.
Just broke 33 inches for my waist and am maintaining my 180 pounds.
A growing
body of research suggests that intermittent fasting may in fact be a key weight
loss tool. It appears particularly powerful when combined with exercise—i.e.
working out while in a fasted state. According to some fitness experts, such as
Ori Hofmekler—whose guest commentary is featured below—fasting may indeed push
your exercise program to the next level.
It can
also boost general health and longevity, but as Ori explains later in this
article, there are tradeoffs—you cannot achieve maximum fitness and maximum
longevity at the same time. You have to chose one or the other and tailor your
diet and fitness regimen to achieve your intended goal. Gender differences also
come into play when fasting, which you need to be aware of.
For the
last several months I have been experimenting and not eating breakfast and
compressing the time that I eat into a 6-7 hour window. I do this nearly every
day of the week and it has helped me drop my body fat percentage effortlessly.
Interestingly, hunger is not much of a problem as I have shifted to upregulate
my fat burning enzymes. I am convinced that having periods of 12-18 hours of
fasting is likely highly beneficial. The other variable I am currently in the
process of evaluating if dinner would be the better meal to skip. Skipping
breakfast is far easier and logistically and socially more acceptable, but
avoiding dinner might be better from a health perspective.
Boost
Fitness Results and Weight Loss with Intermittent Fasting
Exercising
on an empty stomach has been shown to have a number of health and fitness
benefits. It may even be a key to keep your body biologically young. This is most easily
accomplished if you exercise first thing in the morning, before breakfast.
Part of
the explanation for why exercising while fasted is beneficial is that this
regimen complements your sympathetic nervous system (SNS) along with your
capacity to burn fat. Your body's fat burning processes are controlled by your
SNS, which is activated by exercise and by lack of food. Another reason is that
fasting can trigger a dramatic rise in human growth hormone (HGH), also known
as "the fitness hormone." Recent research found fasting raised HGH by
1,300 percent in women and 2,000 percent in men!1
The combination
of fasting and exercising maximizes the impact of cellular factors and
catalysts (cyclic AMP and AMP Kinases), which force the breakdown of fat and
glycogen for energy.
This is
why training on an empty stomach will effectively force your body to burn fat.
Exercise and fasting also yield acute oxidative stress, which keeps your
muscles' mitochondria, neuro-motors and fibers intact. (You may have heard of
oxidative stress before in a negative light, and indeed, when it is chronic
it can indeed lead to disease. But acute oxidative stress, such as
occurs due to short intense exercise or periodic fasting, actually benefits
your muscle.)
Regardless
of when you choose to exercise, remember that you need to eat 30 minutes after
your workout, which will effectively break your fast. If you exercise in the
late morning or early afternoon, you could break your fast by including 20
grams net protein from a fast-assimilating source like a high-quality
whey protein concentrate 30 minutes before you start your exercise, and then
have another recovery meal 30 minutes after.
Intermittent
Fasting for General Health and Longevity
There's
plenty of research showing that fasting has a beneficial impact on longevity in
animals. There are a number of mechanisms contributing to this effect.
Normalizing insulin sensitivity is a major one as insulin sensitivity is
critical for the activation of the mTOR pathway, which along with IGF-1 plays
an important part in repairing and regenerating your tissues including your
muscles and thereby counteracting the aging process. The fact that it improves
a number of potent disease markers also contributes to fasting's overall
beneficial effects on general health. For example, modern science has confirmed
fasting can help you:
- ·
Normalize
your insulin sensitivity, which is key for optimal health as insulin resistance
(which is what you get when your insulin sensitivity plummets) is a primary
contributing factor to nearly all chronic disease, from diabetes to heart
disease and even cancer
- ·
Normalize
ghrelin levels, also known as "the hunger hormone"
- ·
Promote human
growth hormone (HGH) production, which plays an important part in health,
fitness and slowing the aging process
- ·
Lower
triglyceride levels
- ·
Reduce
inflammation and lessening free radical damage
While
much of the research is profoundly positive, questions have been raised about
certain studies where results in human subjects have been less than ideal.
Below, fitness expert Ori Hofmekler delves into some of the pitfalls that
plague some of the human studies on intermittent fasting, which make the results
of such studies unreliable. He also offers a few caveats to successful IF, such
as the necessity to avoid the standard American diet when you do eat, as
your body requires high quality nutrients when you're doing intermittent
fasting. He also reviews some of the gender differences, and why you need to
decide on a goal—either maximum fitness, or maximum longevity.
Guest
Commentary by Ori Hofmekler
Studies
on animals reveal that intermittent fasting (IF) can improve health and extend
lifespan similar to calorie restriction. Both regimes have shown to protect
against diabetes, cardiovascular disease, neurodegenerative disorders and
cancer. Animals on IF have demonstrated some major physiological changes,
including:
·
Decreased
plasma insulin
·
Decreased
blood sugar concentrations
·
D blood
pressure
·
Decreased
heart rate
·
Enhanced
immune function
·
Reduced
body fat
Human
Trials on Intermittent Fasting
That's
how animal respond to a low feeding frequency. But what about humans? Is the
human body programmed for a low meal frequency? Only a few experimental studies
have tested the effect of intermittent fasting (IF) on humans. Apparently there
have been conflicting reports concerning the results.
There
were some indications of adaptation issues among subjects who did not become
'habituated' to the low meal frequency – particularly the alternate day
fasting. Subjects seemed to feel increased hunger and desire to eat, and a
decreased feeling of fullness during these trials.
The one
meal per day's results were particularly confusing, as they indicated that
though some health improvements were attributed to that regimen, they were only
marginal, and they came along with both adverse and beneficial side effects
such as increased blood pressure, increased cholesterol (good and bad),
decrease in circulating triglycerides, decreased cortisol, and decreased body
fat, respectively.
Overall,
the findings showed only modest changes in body composition, decreases in some
cardiovascular risk factors, and some improvements in cognitive function. These
seem like minor benefits compared to the dramatic results shown in animal
studies.
Why Do
Results from Human IF Trials Differ from Animal Studies?
Though a
possible explanation could be that the human response to fasting is different
than that of animals, the real reason seems to be in the studies themselves.
Apparently, a couple of design flaws have rendered some of these studies unfit
for IF trials. Take a look for instance at the initial human study on reduced
meal frequency by the American Society for Nutrition – three meals per day
versus one meal per day.
That
study had two notable flaws:
1. The subjects on the one meal per
day were force-fed a fixed amount of calories, often despite their spontaneous
tendency to stop eating due to the feeling of fullness.
2. The study's diet design was based
on the typical American diet's food ratio – high carbs – low protein – low
fiber (carbs 50 percent, protein 14.5 percent, fiber 1 percent).
The point
is: force feeding and the typical American diet's food ratio are inherently
counter-effective to IF and therefore yield misleading results in IF trials.
Here is how...
Forced
Feeding Shatters Your Adaptive Response to Fasting
Fasting
has a profound effect on your food cravings as it has shown to shift cravings toward
more subtle tasting, nutrient dense, satiety-promoting foods, which can then
lead to a spontaneous decrease in your overall calorie intake. This is probably
part of an early adaptation mechanism to food scarcity, which encourages intake
of maximum nutrients from minimum food.
And when
that adaptive response takes place, it transforms your body to become leaner,
healthier and increasingly resilient to hunger and fasting. Force-feeding
abolishes this adaptive feature.
This
means that under the study's terms, the subjects on the one meal per day plan
could not possibly adapt to that regimen. However, if they were allowed to
choose their foods freely and stop eating upon feeling satiety, they would have
probably become increasingly adept to fasting, and the study's results would
have been very different. The second flaw in the diet design was that it was
based on the typical American diet's food ratio, and that food ratio is
counter-effective to IF.
The
Typical American Diet's Food Ration Negates the Benefits You Get from IF
The
typical American diet and its high glycemic food ratio will never complement
intermittent fasting, certainly not the one meal per day. Shoving in 40 percent
of the daily calories from refined carbs alone in one sitting will affect your
insulin and your health more than when that amount is divided into three or
several meals.
Yes, if
you eat the typical American portions of chocolate, pie, milkshake or ice
cream, you'd better cut these into as many meals as possible. And note that the
typical American diet with its high carb, low protein, low fiber ratio is known
to promote hunger and weight gain; and it certainly lowers your capacity to
endure fasting.
So what
can you learn from these studies? What should be your right food ratio when
following an IF regimen? What should be your right food choices? And what
should be your right fuel food?
·
Proper Food Ratio: high protein, low carbs, high fiber. Having a low glycemic food ratio
is critical to the viability of your intermittent fasting. Your ideal ratio
would be: high protein – low carbs – high fiber. That ratio has proven to be
most effective in promoting satiety and resisting hunger. The high protein part
serves to nourish and retain your lean tissues whereas the low carb-high fiber
ratio helps optimize your insulin and sustain a healthy metabolism. This
dietary ratio has also shown to be most effective in decreasing body fat while
sparing muscle tissue.
·
Proper Food Choices: Quality protein, green and fibrous vegetables,
nutrient dense fruits, good fat. Your protein should come from chemical-free,
preferably organic whole food sources – fish, pastured eggs, legumes and dairy.
Note that dairy protein, particularly whey, isn't just ok for IF, it actually
enhances the benefits you get from fasting via its unique content of immune
supportive, anti-inflammatory, and tissue regenerating nutrients which include
bioactive peptides, leucine, and calcium.
For fiber and carbs use whole and fibrous plant foods such as greens,
cruciferous vegetables, roots, legumes, corn kernels, wild rice, oats and
barley.
To support your antioxidant and anti-inflammatory defenses, use nutrient
dense fruits such as berries, cherries, citrus, papayas and apples; other
powerful options in this category include dark chocolate (no sugar added), green tea and
quality non-denatured whey protein. Your fat fuel should come from nuts, seeds,
avocadoes, olives, extra virgin olive oil, coconut oil or whole dairy.
Fat will
Typically Accommodate Your Fasting Better than Carbs
Fat fuel
will generally accommodate your fasting better than carb fuel, as it has a
longer and more profound effect on your satiety and your ability to sustain
energy during fasting. Fat fuel increases ketogenesis – an energy pathway that
involves production of ketone bodies, byproducts of fat metabolism – known to
serve as your body's preferred fuel during fasting, when glycogen reserves are
depleted, and glucose supply is limited.
Ketone
bodies have shown to sustain brain and body functions; and incredibly, they
have also demonstrated the capacity to protect against neuronal disease,
seizures, and age related brain diseases, such as Alzheimer's, Huntington's and
Parkinson's. There are however some exceptions to the above.
Cases
where Dietary Fat Should Not Be Your Primary Fuel
Fat
should not be your primary fuel if you suffer from a condition of impaired fat
metabolism such as:
·
Hyperlipidemia
·
Cholesterol
disorder
·
Obesity
related insulin resistance
·
Liver
disease
The other
reason for not having fat as a primary fuel relates to your type of exercise.
If you're a power lifter or engaged in sheer strength training, fat should not
be used as your main fuel. Max strength performance requires carbohydrate fuel,
as you predominantly use your fast glycolytic fibers (Type IIB white fibers),
which are inherently carb dependent and have a very limited capacity to utilize
fat.
Beware of
Differences Between Gender, and Individual Health Goals
Gender is
another important factor in human and animal studies. Female-specific responses
to fasting raise an interesting scientific phenomenon. Researchers have been
finding evidence that there is indeed a tradeoff between virility and longevity
of organisms.
Apparently
the same genes that promote human longevity may trigger biological mechanisms
that suppress female reproductive capacity.
Hence,
fasting and intense exercise protocols, known to promote longevity, also lower
estrogen level and thereby modulate body composition and suppress female
reproductive capacity. This is apparently part of an early adaption mechanism
to primordial conditions of food scarcity and hardship, which requires
increased strength and durability on the account of reproductivity. Hence, hard
conditions are not biologically suitable times for pregnancy and child bearing.
I
discussed this issue with Dr. Marc Mattson, Prof. of Neurosciences at Johns
Hopkins University a few years ago. According to Mattson, women who fast or are
on calorie restriction, have the tendency to get leaner, become increasingly
addicted to physical exercise, and lose their menstrual cycle. Nonetheless,
they seem to gain substantial improvements in all main biological markers of
longevity – i.e. increased insulin sensitivity, increased GH secretion,
improved lipid profile, improved anti-inflammatory cytokine profile, improved
cognitive function, etc.
Note that
fasting triggers the longevity gene SIRT-1, which regulates mitochondrial
energy production along with the gene transcription promoter protein PGC-1α,
which increases mitochondrial biogenesis and density in the muscle. Yes,
mitochondrial energy utilization efficiency is a key to longevity.
One of
the most notable benefits of fasting is its profound anti-inflammatory effect.
Fasting increases production of anti-inflammatory cytokines while suppressing
pro-inflammatory cytokines such as TNF-α and IL-6. Note that pro-inflammatory
cytokines produced by fat cells (adipokines) are associated with insulin
resistance, obesity, metabolic syndrome, and a shorter life span; whereas
anti-inflammatory cytokines, such as adiponectin and IL-15, are associated with
improved insulin sensitivity, increased thermogenesis, decreased fat storage,
increased muscle regeneration and increased life span.
Finally,
in view of the current epidemic of excess estrogen in females and males, caused
by estrogenic chemicals and foods (such as petrochemicals and soy), fasting and
IF can be used as an effective therapeutic strategy to balance estrogen and
prevent related metabolic disorders and cancer.
Summary
Points
·
Don't
blindly trust human studies on IF as some of these show misleading results due
to major design flaws.
·
Don't
even think about intermittent fasting if you eat the typical American portions
of high glycemic junk food.
·
When
following an IF regimen you need to make it low glycemic and high in protein
and fiber. Eat whole foods, possibly high in dairy and whey protein, along with
nutrient dense antioxidant foods.
·
Adjust
your fuel food according to your specific condition and type of training.
·
Your
intermittent fasting regimen must make sense. The length of your fasting
intervals should be optimized to yield maximum biological impact. What really
counts is your net fasting time (period between meals minus digestion time.) It
takes your body roughly 5-8 hours to fully digest a meal and shift into a
fasting mode. Three to six hours of "not eating" between meals will
not be sufficient to put your body in a fasting mode and therefore will fail to
get you the results you're looking for.
·
The
female-specific response to fasting or intermittent fasting is no different
than the female response to intense exercise. There is indeed a tradeoff
between benefits and side effects. And the question "should women
fast" raises the same issues as the question "should women exercise
intensely".
About the Author
Additional
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