We all have this person in our life – the health nut. He or
she might be a certified personal trainer or just really addicted to exercise.
However, these people have one thing in common that really ticks you off sometimes
(or just annoys you slightly depending on how much you think they know what
they’re talking about): they are always trying to tell you the best way to exercise
and eat. Whenever this happens, which is quite often, that voice in your mind
(or at least my mind) goes, “where is he/she getting this information? Is this
actually true? Will this even work?” If the voice in your mind doesn’t say this
or something along the lines of this, you will probably not be interested in
this blog.
Chances are, the source of
information for them is someone else, who heard it from someone else, and not
from actual research. Chances are, that even if they did glimpse it from a
study (and I emphasize glimpse), the study was not done in a manner that warrants
the conclusions that were made. Chances are, you are a curious, intelligent
person like me who just wants the best information out there about health and
fitness. Sounds like you? Then follow this blog series, where I will critically
assess the scientific literature behind popular fitness advice (if any exists
at all). I will judge the body of research behind a claim using my scientific
eye, and help you assess whether the claim is actually close to the truth, and
the advice worth following.
Popular fitness advice #1: Cardio is ineffective for
weight-loss
I’m
starting my blog on this popular fitness myth that a lot of health nuts like to
hand out. It was inspired by a conversation I had with a friend who loves
cardio but hates weight-lifting. I realized that I have this conversation with
people ALL the time! Usually, I hand out the advice I was given: weight-lifting
along with cardio is most effective for weight-loss. (You probably realize by
now that yes, I am a health nut to many people). I got this advice from the
internet, probably one of the gazillion websites that give fitness advice. I
also confirmed this with a personal trainer friend of mine (my health nut, yes
it’s like a pyramid scheme, get used to it - this is the fitness industry folks). After
diving into the literature though, I think the answer is not as clear-cut as it
might seem. However, before we get deep into the science, we need to start from
the basics.
First, what is
weight-loss? I think most people think of weight-loss simply as reducing the
number on the scale. But I think most people would also like those lost numbers
to be coming from dying fat cells. This is where it starts to get complicated.
In order for scientists to do
science, we need to be able to measure something accurately and reproducibly.
However, scientists are people, and people are naturally lazy, so we like to
simplify problems (see my previous post for what can go wrong when people get
REALLY lazy).
A given experiment usually goes
something like this: an older professor or health professional got some money
to do some work about a given topic (here weight-loss and exercise). He
recruits a few young, bright, eager minds (could be undergraduates, graduate
students and/or health professionals, sometimes even high-school students) to
do the research. They write up a plan for the experiment. At least two groups
will be involved: a control group and the treatment group. In this example,
depending on how ambitious the professor is, the control group could be doing no
exercise at all or their regular routine. The treatment group will receive a
more rigorous exercise schedule to be followed. Then the professor tells the
students to do the work. They recruit some people who want to lose weight. Initially,
there might be a lot of volunteers or people interested. Some of these poor
people will be put in a control group and not achieve the goals they wanted to
achieve. These people might get mad and drop out. As the experiment continues,
some people might not be following what they are supposed to do. Some people
might get into some family issues and forget about their experiment, or simply
drop out. As time progresses, more and more people drop out, and most people
will not have followed the program to the level that the researchers would hope
for. At last, the initially eager young minds become frustrated and bitter young
minds. They might themselves quit, leaving the experiment in tatters. They
might push through all the problems and finish up the research. However, for an
experiment to be trustworthy (for us to believe that their conclusions are
justified, that what they saw is real, that the same things will occur in real
life again and again), many things need to happen. There needs to be enough difference in terms of the measurements made between the groups, and
enough people in each group, for the statistical gods to bless us with a significant
P-value (or “real”, although this
point is also arguable). Since so many people have dropped out of the
experiment, we can probably imagine that the results from this hypothetical
experiment are not trustworthy.
As you can see, a lot of things can
go wrong when doing science. Of course, everything could go smoothly and you
get great results, but this rarely happens (Murphy’s law – everything that can
go wrong, will). Luckily, scientists are not stupid. We try to circumvent these
problems before they happen by designing experiments that avoid running into
these types of issues. Most of the science done in the fitness field these days
are done using high-tech machines to accurately measure athletic performance (ex.
force output, activation of certain muscles/neural circuits) in a short time
frame. This way you get definite and reproducible measurements quickly.
However, you can’t measure weight-loss in a short time frame (unless you sit in
the sauna for a few hours).
I digress. Now that I have dealt with the
scientific sidebar, and you know what real science is like, we can deal with
the question in mind. However, things continue to be complicated.
You know when you have a family
dinner. Your mom and dad are cooking, and they have an argument over how to
cook the roast. You dad read somewhere that straight 350F for 3 hours is the
best, while your mom knows from experience that searing the meat first, then 300F
for 4 hours leads to be most tender and juicy roast. The point is, people are
very opinionated, and have very different ideas about how one should approach a
problem. Well, scientists are also people, so they also like to approach the
same question – here, what is the most effective way to lose weight – in very
different ways. This makes assessing which experiment has the most definitive
answer to the question much more difficult, because everyone wants to roast the
beef at a different temperature.
To be continued...
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