ALTERNATE DAY FASTING IS NO BETTER THAN ANY OTHER FAD DIET
In his Obesity Notes blog,
Dr Arya Sharma recently reviewed a year-long randomised controlled
study by John Trepanowski and colleagues that showed alternate day
fasting is evidently no better in producing superior adherence, weight
loss, weight maintenance, or cardio-protection compared to good old
daily calorie/kilojoule restriction (which also produces modest
long-term results at best).
“It seems that every
year someone else comes up with a diet that can supposedly conquer
obesity and all other health problems of civilization. In almost every
case, the diet is based on some “new” insight into how our bodies
function, or how our ancestors (read – hunters gatherers – never mind
that they only lived to be 35) ate, or how modern foods are killing us
(never mind that the average person has never lived longer than ever
before), or how (insert remote population here) lives today with no
chronic disease. Throw in some scientific terms like “ketogenic”,
“gluten”, “anti-oxidant”, “fructose”, or “insulin”, add some level of
restriction and unusual foods, and (most importantly) get celebrity
endorsement and “testimonials” and you have a best-seller (and a
successful speaking career) ready to go.
Source
The
problem is that, no matter what the “scientific” (sounding) theories
suggest, there is little evidence that the enthusiastic promises of any
of these hold up under the cold light of scientific study. Therefore, I
am not the least surprised that the same holds true for the much hyped
“alternative-day fasting diet”, which supposedly is best for us, because
it mimics how our pre-historic ancestors apparently made it to the ripe
age of 35 without obesity and heart attacks.
The
alternate day fasting group in the year-long randomised controlled study
published in JAMA Internal Medicine had significantly more dropouts
than both the daily calorie restriction and control group (38% vs. 29%
and 26% respectively). Mean weight loss was virtually identical between
both intervention groups (around 6kg).
Purists of
course will instantly criticize that the study did not actually test
alternative-day fasting, as more people dropped out and most of the
participants who stayed in that group actually ate more than prescribed
on fast days, and less than prescribed on feast days – but that is
exactly the point of this kind of study – to test whether the proposed
diet works in “real life”, because no one in “real life” can ever be
expected to be perfectly compliant with any diet. In fact, again, as
this study shows, the more “restrictive” the diet (and, yes, starving
yourself every other day is “restrictive”), the greater the dropout
rate.
Unfortunately, what counts in real life is not
what people should be doing, but what people actually do. The question
really is not whether or not alternate-day fasting is better for someone
trying to lose weight but rather, whether or not “recommending” someone
follows an alternate-day fasting plan (and them trying to follow it the
best they can) is better for them. The clear answer from this study is
“no”. So why are all diets the same (in that virtually all of them
provide a rather modest degree of long-term weight loss)?
My
guess is that no diet (or behaviour for that matter) has the capability
of fundamentally changing the body’s biology that acts to protect and
restore body fat in the long-term. Irrespective of whether a diet leads
to weight loss in the short term and irrespective of how it does so (or
how slow or fast), ultimately no diet manages to “reset” the body-weight
set point to a lower level, that would biologically “stabilize” weight
loss in the long-term.
Thus, the amount of long-term weight loss that can be achieved by
dieting is always in the same (rather modest) ballpark and it is often
only a matter of time before the biology wins out and we put all the
weight back on.
Clearly, I am not holding my breath for
the next diet that comes along that promises to be better than
everything we’ve had before. My advice to patients is: do what works for
you, but do not expect miracles – just find the diet you can happily
live on and stick to it.”
Read more:
- Effect of Alternate-Day Fasting on Weight Loss, Weight Maintenance, and Cardioprotection Among Metabolically Healthy Obese Adults A Randomized Clinical Trial
- Dr Sharma’s Obesity Notes
- How to lose 50 pounds and keep them off (TEDx)
Dr Sharma is Professor of Medicine and Chair in Obesity Research and Management at the University of Alberta, Edmonton, Canada. He is also the Clinical Co-Chair of the Alberta Health Services Obesity Program. He has authored and co-authored more than 350 scientific articles and has lectured widely on the etiology and management of obesity and related cardiovascular disorders and is regularly featured as a medical expert in national and international TV and print media and maintains a widely read obesity blog at www.drsharma.ca.
