In
college, I found that if I ate only one large meal in the middle of the day, I
not only kept weight off but I felt good. With the passing years, pregnancy and
nursing, I definitely got out of that habit, but more recently gastric reflux
has me finishing dinner by 7pm or earlier. So the combination of my brother’s
and my experiences, made me take a closer look at the various articles I was
coming across on IF (intermittent fasting).
A lot
of the research has been done on animal models and looks very promising, but does
it hold true for humans? Is it different for men and women? What about people
with chronic conditions?
For centuries cultures and religions have included
fasting, such as Ramadan for Muslims, Lent for Catholics and Yom Kippur for
Jews. Buddhist and Hindus also have fast days scheduled throughout the year. In hunter/gatherer cultures, it would be feast
of famine. The change, with year round food availability, as well as “snack”
foods, appears to play a part in the high levels of diabetes among Native Americans.
Broadly
speaking IF falls into two categories:
a)
Alternate Day Fasting: Switching between days you eat more (feast) and others
less (fast). There are lots of variations on this with the most popular
appearing to be 5:2, where you fast for two non-consecutive days every week.
b)
Restricted Eating Window: Instead of restricting what you eat, you restrict the
hours you eat. Most popular is the 16/8 method. You fast for 16 hours and eat
for 8.
Research
is slow in catching up with the hype, but there are indications that IF does
help with weight loss, anti aging, diabetes risk reduction cholesterol etc. In
fact, the science of fasting has been focused more on disease prevention and
longevity then weight loss.
A
German study found that while IF does cause weight loss, it doesn’t appear to
have an advantage over conventional weight loss diets. American Journal of Clinical Nutrition
Another study of 88 obese women found that they lost more weight and improved
their health by using IF while following a strictly controlled diet. However, this
was only a 10-week study. Obesity
There
is some research that indicates that IF may help reverse type 2 diabetes, while
some animal studies say it might increase the risk.
Interestingly,
the study that has shown promise in reversing memory loss associated with
Alzheimer’s disease, implemented a 36-point program targeting life styles. One
of these was fasting 12 hours between dinner and breakfast. Reversal of Cognitive Decline.
Researchers
at Johns Hopkins School of Medicine have
found that
intermittent fasting—limiting caloric intake at least two days a week—can help
improve neural connections in the hippocampus while protecting neurons against
the accumulation of amyloid plaques, a protein prevalent in people with
Alzheimer’s disease. “Fasting is a challenge to your brain, and we think that
your brain reacts by activating adaptive stress responses that help it cope
with disease,” says Mattson. “From an evolutionary perspective, it makes sense
your brain should be functioning well when you haven’t been able to obtain food
for a while.” Johns Hopkins Health Review
The
limited research on humans does seem to show that results vary between men and
women. Some women have experienced missed periods, metabolic disturbances and
even early onset menopause. However, other women swear by it. So many variables
could be at play here, including age, whether you’ve had children, been through
menopause etc.
There
are also questions about when is the best time to fast. Some research indicates
eating earlier in the day is better than later. However, given the common
social practice of going out for dinner, this could be problematic for many.
In
short, a lot more research is needed.
All of this
noted, anyone who has diabetes; eating disorders that involve unhealthy
self-restriction (anorexia or bulimia nervosa); use of medications that require
food intake; adolescents; and pregnant or breast feeding women should not
consider IF. Further, anyone with a chronic condition needs to check with their medical
provider before trying a significant diet change and should be monitored for
its effectiveness or possible side effects.
Further
Reading
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