[Music]
Olive Oyl is 100% fat there's nothing
else in it
pancakemix on the other hand is only
about eleven percent fat and yet olive
oil is good for you and pancake mix is
not why is that as it turns out the
amount of fat we eat doesn't impact our
weight or a cholesterol or a risk of
heart disease nearly as much as what
kind of fat we eat but let's back up
what is fat if we were to zoom in on a
salmon which is a fatty fish past the
organs past the tissues into the cells
we would see that the stuff we call fat
is actually made up of molecules called
triglycerides and they are not all alike
here's one example
those three carbons on the Left that's
glycerol now you can think of that as
the backbone that holds the rest of the
molecule together the three long chains
on the right are called fatty acids and
it's subtle differences in the
structures of these chains that
determine whether a fat is let's say
solid or liquid whether or not it goes
rancid quickly and most importantly how
good or how bad it is for you let's take
a look at some of these differences one
is length fatty acids can be short or
long another more important difference
is the type of bond between the carbon
atoms some fatty acids have only single
bonds others have both single and double
bonds fatty acids with only single bonds
are called saturated and those with one
or more double bonds are called
unsaturated
now most unsaturated fats are good for
you while saturated fats are bad for you
in excess for saturated fats the story
pretty much ends there but not for
unsaturated fats the double bonds in
these molecules have kind of a weird
property they're rigid so that means
that there are two ways to arrange every
double bond the first is like this where
both hydrogen's are on the same side and
both carbons are on the same side the
second way is like this now the
hydrogen's and carbons are on opposite
sides of the double bond now even though
both of these molecules are made up of
exactly the same building blocks they
are two completely different substances
and they behave completely differently
inside of us the configuration on the
left is called sis which you've probably
never heard of the one on the right is
called trans and you probably have heard
of trans fats before they don't go
rancid there
more stable during deep-frying and they
can change the texture of foods in ways
that other fats just can't they're also
terrible for your health by far worse
than saturated fat even though
technically they're a type of
unsaturated fat now I know that seems
crazy but your body doesn't care what a
molecule looks like on paper all that
matters is the 3d shape where the
molecule fits where it doesn't and what
pathways it interferes with so how do
you know if a food has trans fat in it
well the only sure way to know is if you
see the words partially hydrogenated in
the ingredients list
don't let nutrition labels or
advertising fool you the FDA allows
manufacturers to claim that their
products contain quote zero grams of
trans fat even if they actually have up
to half a gram per serving but there are
no hard and fast rules about how small a
serving can be and that means you'll
have to rely on seeing those keywords
partially hydrogenated because that's
how trans fats are made by partially
hydrogenating unsaturated fats so let's
go back to our olive oil and pancake mix
from before olive oil is 100% fat
pancake mix is only eleven percent fat
but olive oil is mostly unsaturated fat
and it has no trans fat at all on the
other hand more than half the fat in
pancake mix is either saturated or trans
fat and so even though olive oil has ten
times as much fat as pancake mix it's
healthy for you whereas pancake mix is
not now I'm not trying to pick on
pancake mix there are lots of foods with
this type of fat profile the point is
this it's not how much fat you eat it's
what kind of fat and what makes a
particular fat healthy or unhealthy is
its shape
you