There is a way to reduce blood sugar, improve insulin sensitivity,
reduce blood pressure, increase HDL levels, get rid of diabetes, live a
lot longer, and still be able to lose a little weight. All without
giving up the foods you love. And without having to eat those foods in
tiny amounts. Sounds like a late-night infomercial gimmick, but it
isn’t.
Before I get to the real nitty gritty of how such a thing can be
done, let’s look at a method that has been proven in countless research
institutions to bring about all the above-mentioned good things. It’s
called caloric restriction.
When researchers restrict the caloric intake of a group of lab
animals to about 30 to 40 percent of that of their ad libitum (all they
want to eat) fed counterparts, they find that the calorically
restricted animals live 30 percent or so longer, don’t develop cancers,
diabetes, heart disease, or obesity. These calorically restricted (CR)
animals have low blood sugar levels, low insulin levels, good insulin
sensitivity, low blood pressure and are, in general, much healthier
than the ad lib fed animals.
Most of the work in caloric restriction has been done on rodents,
but there is a long term study on Rhesus monkeys (17 years at this
point) that appears to confirm the rodent data on longevity and health
with CR in primates. There are no human longevity studies, but there
are a number of human studies on CR and health that show that human
subjects under CR conditions reduce blood sugar, improve insulin
sensitivity, reduce blood pressure, etc., so it stands to reason that
if humans reduced their caloric intake by 30-40 percent for their
entire lives, they would also live longer.
Caloric restriction is a terrific way to lose weight and get
healthy; problem is, it’s not much fun. When rats live out their little
ratty lives calorically restricted in their cages they seem to show
signs of depression and irritability. Primates do for sure. If primates
don’t get enough cholesterol, they can actually become violent. But, if
you’re willing to put up with a little irritability, hostility and
depression, it might be worth cutting your calories by 30 percent for
the rest of your long, healthy miserable life.
Doesn’t sound so cheery? You’re not ready to sign up yet?
Well, there is a better way.
A number of different research teams have studied a method by which
rodents can get all the health and longevity benefits of caloric
restriction without calorically restricting. And the method has been
studied in humans and seems to achieve the same health benefits and, if
an old Spanish study can be believed, maybe even an increase in
lifespan.
What is this magic method?
Intermittent fasting.
In regular fasting one goes entirely without food, which is caloric
restriction carried to the extreme. Going entirely without food in the
short term leads to improvement in health, but also leads to an
extremely short life unless the fast is aborted.
Intermittent fasting (IF) is just as its name implies: a period of fasting alternated with a period of eating.
But isn’t that what we do anyway? We eat breakfast, then fast until
lunch. Then, after lunch, we fast until supper. Then we fast all night.
Uh, not exactly.
In research settings animals that are intermittently fasted are fed
every other day, so they eat whatever they want for a day, then they
are denied food for a day. Interestingly, on feeding days most of the
animals eat a almost double the amount that their ad lib fed mates do.
Thus the IF animals eat about the same number of calories overall that
the ad lib fed animals eat, but, and this is a huge ‘but,’ the IF
animals enjoy all the health advantages that the CR animals do, and, in
fact, are even healthier than the CR animals.
Like caloric restriction, intermittent fasting reduces oxidative
stress, makes the animals more resistant to acute stress in general,
reduces blood pressure, reduces blood sugar, improves insulin
sensitivity, reduces the incidence of cancer, diabetes, and heart
disease, and improves cognitive ability. But IF does even more. Animals
that are intermittently fasted greatly increase the amount of
brain-derived neurotrophic factor (BDNF) relative to CR animals. CR
animals don’t produce much more BDNF than do ad libitum fed animals.
I practice IF, but not intentionally. Fasting and hunger kind of create a feedback loop: as you get less hungry, you eat less often, which decreases your insulin levels, which keeps you from getting hungry, and so on. I occasionally eat breakfast, but most of the time I eat once after classes (either at noon or around 3, depending on the day), then again sometime between six and bedtime. Some days that means 14-15 hours without food, some days more like 10-12, but it's definitely in light IF territory.
The Japanese do this, though they don't call it intermittent fasting. My host dad would always tell me, "Eat all you want at meals, but don't eat outside of meals. Bedtime snacks make you fat." Since dinner was at 7 or 8, this means that everyone fasted for about 12 hours a night. This may explain why the Japanese are in such good shape, considering the high carbohydrate content of their diets.
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