- I get comments on my YouTube videos quite frequently
that go something like this, "I think you're wrong.
I did this and it worked for me,
so that's what people should do."
Nutrition is something that many of us
have strong opinions on, and I get it, we all have to eat.
Some are positively tribal with their opinion.
Vegans, yes, I'm looking at you.
And those of you who regularly watch my channel
know that I'm a little bit evangelical
about the whole low-carb thing,
but in this video I'm going to tell you why.
When it comes to answering important questions,
such as which is more effective for weight loss,
low-carb diets or low-fat diets,
you should ignore what Joe Blogs who lost 15 pounds
on a potato-only diet in the early 90s says,
and why you should definitely forget
what Dr. Dan Maggs has to say,
even though I'm a medical doctor,
even though I reversed my own obesity
by following a ketogenic low-carb diet.
We need to look at this little thing
called scientific evidence.
(upbeat music)
Let me tell you about the most extensive study
of low-fat diets ever conducted.
It was called the Women's Health Initiative
Dietary Modification Trial,
and it was a study of nearly 50,000 postmenopausal women
with almost 20,000 randomly chosen to go on a low-fat diet.
What was particularly impressive about this study
was the length of time that it ran for,
and it showed that after seven and a half years,
the women on the low-fat diet
had lost a greater amount of weight
than those in the control group,
and in part, due to the huge size of this trial,
they could say with confidence
that this finding did not occur by chance.
The result was statistically significant.
Great, so low-fat diets work then. Hmm.
What if I told you that the average weight loss
in the low-fat diet group was just 0.4 kilograms?
Yes, that's about a pound. Big wow.
So yes, from a scientific point of view,
it's a statistical win for a low-fat diet,
but I think common sense tells us
that one pound is a disappointing payoff
for seven years of restricting fat, right?
So should we listen to this study? No.
That's an example of cherry picking one study
that suits our agenda.
It's certainly interesting
as a piece of standalone information,
and depending on how you present the results
you can lead people to think,
"Well, yes, low-fat diets work,"
but then adding in that one data point,
the whopping 0.4 kilograms of weight loss,
changes everything.
We have a completely different perspective
when we learn just how underwhelming the results were.
It's not even a study that answers the question
we're trying to ask.
It doesn't even compare low-carb diets to low-fat diets.
It compares low-fat diets to a standard diet.
Now, we're not always fortunate to be able to find
high-quality studies that have attempted to answer
the very question that we are asking.
High-quality studies cost a lot of money to run.
The really big ones are usually related to medications.
Ultimately, a successful study would mean
that a pharmaceutical company makes a significant profit,
so it is worth them being funded.
But we do have high-quality studies in this case.
We have trials that compare low-carb diets to low fat-diets,
and from time to time new ones crop up in the news.
So how do we know whether the latest media headline
is worth paying attention to?
We don't go many weeks between headlines that read
landmark new study pits diets head to head and reveals.
Does it really matter what that study reveals?
Well, it matters to the media.
It helps them sell newspapers
and get clicks on their online pages
where they earn advertising revenue.
It also plays into how our brains work
because the human brain tends to take the newest information
and attach the most significance to it.
This is called recency bias, but it's not how science works.
Just because that study is new doesn't mean it's any better
than all of the studies that came before it.
In fact, it might be worse.
Not all studies are created equal in terms of quality.
Most of those studies simply report
that X is associated with Y.
Just because they found an association
doesn't mean that X causes Y.
Importantly, association is not the same as causation.
Randomized control trials are the gold standard
when it comes to studies,
and only randomized controlled trials
can establish cause and effect.
So in the hierarchy of evidence,
associational observational studies sit well below
randomized controlled trials,
but both of these study types sit above expert opinion.
And any new study that is published
doesn't exist in isolation.
It doesn't supersede every study
that has been done before it.
It simply adds further data to the pool of evidence
that was already available.
This is why the very highest level of evidence
comes from when we view
all of the available randomized control trial data together
without excluding studies that we don't like the results of.
Thankfully, when it comes to the question
of low-carb versus low-fat diets,
that's been made very easy for us
by our friends at the Public Health Collaboration.
They actively maintain a list
of all the randomized controlled trials
that have looked at this issue.
So what does the totality of the evidence say?
Well, there have been 67 randomized controlled trials
that have examined this issue so far.
58 of those trials reported more weight loss
in the low-carb group.
Seven of those trials reported more weight loss
in the low-fat group.
However, not all of those results reached the threshold
of a statistically significant result,
meaning that some of this
could have been down to random chance.
When we look at which of these studies
showed statistically significant results,
36 showed more weight loss for those on low-carb diets,
whereas none of the trials showed greater weight loss
for those on low-fat diets.
Now, you're welcome to go
and check that website out for yourself,
and I'll leave the link to it
down in the description below this video.
But hopefully now you at least have an idea
that when we examine all of the evidence,
it finds overwhelmingly in favor of low-carb diets
when compared with low-fat diets.
The big question is why, in the face of all this evidence,
does government advice worldwide
still focus on low-fat calorie restricted diets?
Well, maybe it's because the whole low-fat diet thing
fits in with the also frankly nonsensical view
that saturated fat causes heart disease,
but maybe it's because of what it's always about, money.
After all, big pharmaceutical companies make a lot of money
from selling pills to slow the progression of illnesses.
It's not in their interest
to have people cure their own poor health
by changing their diets.
And the big food industry spends billions annually
sponsoring high profile sporting events,
like the World Cup or the Olympics.
They don't do this to be nice.
They do this to associate their products with sports
to promote the message that we can eat what we want to
as long as we do enough exercise to burn it off.
They want us to continue to believe
the calories in, calories out mantra
so we keep buying their products.
It's these big food companies
and big pharmaceutical companies
that fund a lot of scientists and scientific studies,
and those scientists sit on the boards
who come up with these guidelines.
These companies also pay vast sums of money
to our governments in the form of taxes,
so why would our governments bite the hand that feeds them
by changing the dietary guidelines
to something that actually works?
Maybe I'm just being cynical. I'll let you decide.
If you started this video
wondering which would be the best diet for you,
hopefully the information I've presented here
will help you make an informed decision,
and if that informed decision is to start a low-carb diet
and you'd like some support with that,
then come and join my next eight-week challenge.
My team and I will support you
through everything you need to know
to be successful on your journey.
And you can find more about that challenge
by visiting carbdodging.com/challenge,
and I'll leave the link to that in the description below.
I hope you found this video helpful.
If you have, please give it a thumbs up.
That stuff really helps.
If you think this video would help someone you know,
please share it with them.
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so you see when I upload a new one.
Have a fantastic day,
and hopefully I'll see you in the next one.