Fast-5 Diet and Lifestyle: [fast5] Fasting, exercise, and diabetes

Thursday, December 16, 2010

[fast5] Fasting, exercise, and diabetes

Hi all,

First I'd like to say, tomorrow marks two years on Fast-5 for me. Still lovin' it, not likely to ever go back! :)

Second, my doctor sent out an e-mail newsletter today with some very interesting information in regards to exercise after fasting, low-carb vs low-fat, and insulin resistance. Looks like he summed up a lot of what we talk about here and threw in a couple of studies for verification. Keep in mind, he specializes in sports medicine and nutrition so it's written with a slant towards athletes and people who may be competitive in sports.

Enjoy!
Rick

Dr. Gabe Mirkin's Fitness and Health E-Zine
December 16, 2010

Exercising on an Empty Stomach Can Both Prevent and Treat Diabetes

One of three North Americans will become diabetic because
they eat a high-calorie, high-fat diet that *blocks insulin
receptors *to prevent cells from responding to insulin (insulin
resistance) *to cause high insulin levels *that constrict coronary
arteries *to cause heart attacks. Failure to respond to insulin
causes *high blood sugar levels *that cause sugar to stick to cell
membranes *to permanently damage the affected cell *to cause
blindness, deafness, heart attacks, strokes, amputations and all
the terrible side effects of diabetes.
After just a few days on a high-calorie, high-fat diet,
cells fail to respond adequately to insulin, blood sugar levels
rise, fat deposits in your body, even in muscles, and you gain
weight. This causes your muscles to start to lose their ability
to store glycogen, the major source of efficient fuel for exercise,
and you tire much earlier during exercise.
If you exercise vigorously BEFORE breakfast, you can
reduce and even prevent these side effects. Exercising after
fasting prevents fat from being deposited in muscles and helps
muscles to make more stored sugar (glycogen), the primary efficient
fuel for exercise. A study from Leuven, Belgium shows for the first
time that "fasted training is more potent than fed training to
facilitate adaptations in muscles, and to improve whole-body
glucose tolerance and insulin sensitivity" (Journal of Physiology,
November 2010). So you are able to exercise longer and harder.
If you do not exercise during this period, you gain none of these
benefits. If you exercise after eating, these benefits are reduced
markedly (Physiology, April 2005).
When you exercise after fasting, you burn primarily your
own body fat for energy. The fat is removed from fat cells and
muscle cells. Muscle enzymes burn fat more efficiently and clear
further fat from your muscles and fat cells to make your cells
more sensitive to insulin. This reverses the cascade described in
the first paragraph.
However, fasting before exercising harms training and
competitive performance in athletes. The limiting factor to how
fast you can move your muscles is the time it takes to move
oxygen into muscles. When you fast before exercising, you burn
more fat and less sugar. Since sugar requires less oxygen than
fat to be converted to energy, your needs for oxygen are greater
to burn fat. This slows you down and tires you earlier.
The basic research that showed how muscles convert sugar
to energy was done in the 1930s by Diana's father, professor
Donald Purdie of Cambridge University in England. He worked
with Hans Adolph Krebs, who won the Nobel Prize for Physiology
or Medicine in 1953.
It is not established whether athletes should train on a
low carbohydrate diet to teach their muscles to burn sugar more
efficiently. This would help them to compete at a faster pace.
Several studies show that training after fasting increases enzymes
that turn sugar into energy. However, training with reduced sugar
stores (glycogen) can limit workouts, and this may counteract the
gains of fasting before working out.