Why do you wait to eat on workout
days?
“I think that unless you’re trying to gain mass or compete in Crossfit
for example, everyone should exercise fasted. We evolved in that
condition. You wouldn’t have run or chased animals right after a meal.
My reason for exercise is cardiovascular health and to burn fat. You
do that best with no food floating around in your system. All morning,
I’ll use the stored glucose in my body for energy. By the time I hit the
gym, I’ll have mostly stored fat left to burn, and will dispose of the rest
of my glucose. Then after the workout, the carbs (glucose) I consume
replenish glycogen rather than being converted to fat tissue.”
There are a lot of variations on how to
fast. I’ve seen fasting limits of 24 or 36
hours. What’s the longest fasting period
you’ve seen?
“The longest fasting period was 300 and something days. This was an
obese man trying to lose weight, under medical surveillance. You have
that fat in your body, and you can just keep losing it. He was taking in
nutrients and electrolytes and being monitored. This was a very extreme
circumstance, but long fasts are possible to do.
One of my favorite books is The Perfect Health Diet by a husband and
wife duo (Paul Jaminet and Shou-Ching Jaminet). It’s probably the best
book on nutrition I’ve seen.
They point out studies which say 16 hours is a good fasting time period
where your body begins initiating autophagy. They bring up that you
can fight infections better with a little autophagy. Infectious diseases
don’t want us to clear out our bodies, so rejuvenating our cells has a
positive effect on the immune system.
I’m interested in the relationship between
exercising and fasting. Is there any in-
stance of becoming too tired from lack
of food?
“No, I wouldn’t worry about being too tired at all. If your whole goal
is to build muscle, then fasting can be tough. However, it’s still doable
depending on how long your eating window lasts and what you eat.
If you aren’t eating enough protein or enough carbs for energy, then
you’re going to have trouble building muscle.
If a weightlifter is looking to go up in muscle size and isn’t worried
about taking on fat with muscle as bodybuilders do, then it’s better
to just eat all the time and not engage in fasting.
The body is always practicing autophagy to some degree, except maybe
not the hour after Thanksgiving dinner.
Your body is pretty smart. The processes which kick in when you fast
happen for a reason, so taking advantage of those changes makes sense.
There’s another cool thing that fasting does. When you calorie restrict
daily, there’s a concern about your resting metabolic rate changing. But
according to research described by Nephrologist Dr. Jason Fung, when
you shrink your eating window and fast, you still get a lot of benefits
of less body fat without lowering your metabolic rate. This is different
than when you restrict total calories, then your metabolic rate declines
to conserve energy. So it becomes difficult to lose fat.”
However, I think for longevity of health, it’s better for most people to
participate in a fasting window as often as possible.”
The Intermittent Fasting Glossary
EATING WINDOW – The length of time each day where fasting is not
practiced and calories may be consumed.
ANABOLIC STATE – A condition of the human body where tissue obtains
energy for growth and maintenance.
GLUCOSE – Simple sugar that the human body uses as energy.
GLYCOGEN – A storage of carbohydrates in the body.
MACRONUTRIENTS – A type of food (fat, protein, carbohydrate) required
in large amounts in the human diet.
4
HYPOGLYCEMIC – The condition of having low blood sugar.
METABOLIC RATE – The rate of metabolism or the amount of energy
used over a period of time.
INSULIN – A hormone that regulates the amount of glucose in the blood.
Lack of insulin causes a form of diabetes.
KETOGENIC – A low carbohydrate state which forces the body to burn
stored fat.
VITAL SIGNS Volume 13 • Issue 2