is a low-carb diet better than a low-fat
diet for fat loss let's talk about that
how's it going guys my name is richie
kirwan and today we're going to talk
about one of the greatest nutrition
rivalries of all time you see people
always want to know which is the best
approach be it conventional versus sumo
deadlifts it's conventional by the way
cardio versus weights weights one's
hands down vegan versus carnivore
personally i'm a big fan of the kearney
vegan diet and today we're going to talk
about the difference between low-fat and
low-carb diet approaches and which if
any is better for fat loss along the way
we'll also talk about how our body
stores and burns fat and how weight loss
and weight gain happen before i go any
further i want to point out that i'm not
going to recommend any specific diet in
this video in my opinion one of the most
important factors of any diet is
someone's ability to enjoy it and stick
to it long term that means that the diet
one person can stick to really easily
may be very different from a diet that
someone else enjoys and can adhere to if
you take anything from my videos i
really hope you learn that you don't
have to restrict yourself to believing
in one single dietary approach for
everyone humans don't work that way and
neither do diets so first off i think
it's a good idea to talk about how we
actually burn fat in the first place our
body fat is called adipose tissue and
one of its main functions is to store
energy in the form of triglycerides a
triglyceride is a molecule made up of
three fatty acids joined to a molecule
of glycerol triglycerides or fats are a
really great way of storing energy
because they can store a lot of energy
compared to other macronutrients one
gram of triglycerides or fat stores nine
calories whereas one gram of either
protein or carbohydrates stores only
about four calories meaning they're less
than half as efficient for energy
storage that said our body does store
some carbohydrate in the form of
glycogen in our muscles and liver and
uses this to maintain our blood glucose
levels when we haven't eaten and as a
fuel for high intensity exercise when we
haven't eaten in a while when blood
glucose levels are normal and when we're
not exercising intensely our body gets
energy from our body fat an enzyme
called hormone-sensitive lipase breaks
down triglycerides to glycerol and fatty
acids those fatty acids get exported out
of the fat cell and are transported in
the blood attached to a protein
transporter called albumin these free
fatty acids travel around the body to
provide fuel for cells simple right now
if we burn more fat from our fat cells
than we eat over time we lose body
weight now when we eat a meal with a mix
of protein carbs and fats something
different happens when we digest our
food protein and carbs get absorbed
directly into our bloodstream from the
gut in the form of amino acids and
sugars the increase in blood sugar and
amino acids causes our body to produce
insulin which is a really important job
it helps to bring our blood sugar back
down to normal levels because high blood
sugar for a long time can be bad for our
health so there are a few ways that
insulin brings our blood sugar back down
the first thing is it inhibits hormone
sensitive lipase so we don't get any
more fat britain this means our body has
to burn carbohydrates or amino acids
instead for energy this means your body
is in a glycolytic state burning glucose
for energy insulin also increases
storage of both glucose and free fatty
acids to help get them out of your
bloodstream glucose can be stored as
glycogen and if your glycogen stores are
at their limit then glucose can be
converted to fat in the liver and stored
as body fat free fatty acids get
converted back to triglycerides and
stored as body fat too so with this
explanation it's very easy to think holy
crap if i eat carbs and raise my insulin
then i'm going to be storing fat all the
time all i need to do is not eat carbs
my insulin will be low i'll start
burning fatty acids and i won't store
any more body fat right while that makes
a lot of sense on the surface it's
actually way too simple a way of
thinking about and completely ignores a
very important point known as energy
balance you see no matter what fuel we
use carbs or fats our body still needs
to use the same amount of energy to be
alive and active more or less if you
don't eat enough food to meet those
needs your body will be in a negative
energy balance and over time you'll lose
body fat on the other hand if you eat
more food than your body needs to burn
to survive this is called positive
energy balance that extra energy you get
from your food needs to go somewhere our
bodies in general don't like waste so
that extra energy will get stored as
either glycogen if there's room or body
fat which humans have a virtually
unlimited storage capacity for and over
time that leads to weight gain so if you
go on a carb-free diet that doesn't
spike your insulin and get most of your
energy from fat while it might be nice
to think that you won't be able to gain
body fat because you're just burning fat
the truth is different if you eat more
fat you will burn more fat but you're
burning the fat you're eating and if
you're eating more fat than you burn you
will store that extra as body fat
because you don't need high insulin to
store fat excess calories is more than
enough okay so far anything i've spoken
about is what we call the mechanism of
fat loss but how does that all play out
in practice do we have any weight loss
studies that compare low fat with low
carb well luckily enough we have a lot
of such studies so let's talk about one
of the best controlled low fat versus
low carb studies which was run by kevin
hall at the national institute of health
in the us it had 19 participants with
obesity the average body mass index was
35 and it was performed in a metabolic
ward that means that the participants
lived in the research center during the
experiment and all the food that they
ate and exercise they did was monitored
to the highest possible level it was a
crossover design which meant that all
the participants got to do both the
reduced fat high carb and the reduced
carb high fat diet for two weeks each
with a two to four week washout period
in between both diets were isocaloric
which means they had the same calories
and put the participants in a 30 energy
deficit both diets also had the same
amount of protein at about 20
in nutrition science like this it's
really important to be able to control
as many factors as possible so that you
know that any differences in results are
caused by in this case the difference in
carbs and fats so what happened well as
you'd expect on the reduced carb diet
insulin dropped more than 20 percent on
top of that fat oxidation or fat burning
increased a lot again as you'd expect
considering the participants were
getting most of their energy from fat
now at this point i'm going to remind
you that the extra fat oxidation is
going to be a combination of burning
body fat and burning the fat that they
were eating but the interesting finding
was the effect on just burning body fat
which at the end of the day is what
people care about when it comes to a
weight loss study the researchers
calculated that the reduced carb group
was burning 53 grams of body fat per day
but the reduced fat group was actually
burning 89 grams of body fat per day so
overall the reduced fat group was
actually burning more body fat now this
was just a two week study but it does
help to show when it comes to burning
body fat a calorie deficit seems to be a
lot more important than keeping insulin
low because remember that low carb group
had lower insulin but we're burning less
body fat what about longer term studies
in the real world do we have any good
studies comparing low carb and low fat
diets you bet we do professor
christopher gardner ran the diet fits
trial which compared weight loss on a
healthy low fat diet versus a healthy
low carbohydrate diet for 12 months this
was a free living experiment which means
people were living their normal lives
and we're told how to eat that means you
can't monitor what the people do or eat
as well as in a metabolic ward study but
the results are a lot more realistic
because people can't be controlled and
told how to eat in the real life this
study also had over 600 participants
which made the results a lot more
reliable all the participants were given
education on how to either lower their
carbs or fats as much as possible
depending on the group that they were in
the low-fat diet group had an average of
48 carbs and 29 fat and the low-carb
group had an average of 30 carbs and 45
fat and i know people are going to say
that's not very low carb low fat but
this is what people do in the real world
and what happened to 12 months well both
groups on average lost weight the low
fat group lost 5.3 kilos and the low
carb group lost 6 kilos on average so
they lost 700 grams more but this wasn't
statistically significant and 700 grams
over a year isn't really a meaningful
amount of weight loss either also this
study didn't look exclusively at body
fat so part of the difference could be
losses of body water which we know are
greater on low carb diets on top of that
the insulin levels of the participants
had absolutely no effect on weight loss
either what was really interesting about
this study is that it was funded by the
nutrition science initiative or nusei an
organization that pretty much has the
goal of proving that carbs and insulin
cause weight gain so the fact that their
study didn't show that was a pretty big
deal i could talk about a lot more
studies in detail but we have so many
that we even have meta-analyses of
studies a meta-analysis is when you
combine the results of multiple similar
studies to find out what the overall
effect is now there have actually been a
lot of meta-analyses comparing low-fat
and low-carb and other diets over the
years and they have more or less had the
same results one of the more recent
studies used data from 53 other studies
with over 68 000 participants and a
duration of 12 months the analysis
showed that on average the low carb
diets resulted in about
1.15 kilograms more weight loss than the
low fat diet again 1.15 kilograms over
12 months isn't a big difference when it
comes to body weight and we always have
to think how much of that difference is
body water and is there much of a
difference if any in body fat with all
the evidence that we have we can say
that when it comes to fat loss low carb
diets are probably just as effective as
low fat diets we definitely don't have
any evidence to say that low carb diets
have any magic weight loss effect and we
can also say that lowering insulin
doesn't affect weight loss either so
which should you choose low carb or low
fat well that is completely up to you
and what you prefer you see the most
important factor when it comes to
long-term body fat loss is being able to
stick to a diet if you can't stick to a
diet whatever diet it may be because you
hate the foods you're eating then you're
not going to be able to maintain that
weight loss if you want long-term
success you need to find a way of eating
that you can enjoy and stick to long
term for some people that might be lower
fat for some it might be lower carb find
what works for you and don't fall for
all the divisive and dogmatic diet
that you see on the internet every day
as long as you eat fewer calories both
low fat and low carb diets will work i
really hope that's cleared up some of
the confusion about low carb and low fat
diets as always if you have any more
questions let me know in the comments
below and let us know about your own
experience with low carb or low fat
diets and remember hit that like button
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youtube channel for more great
evidence-based nutrition information
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