in today's video we are going to talk about how it is possible that nutrition studies keep
contradicting one another it seems like every week there's a new headline all over mainstream media
making a radical health claim a slice of bacon a day increases your risk of cancer a cup of
fruit reduces your diabetes risk olive oil can extend your lifespan sometimes these headlines
are consistent and follow a similar narrative but other times they directly contradict one another
it can be very overwhelming trying to figure out what to eat with so much conflicting information
coming at us from all angles how on earth are we supposed to know what we should be eating the good
news is that there are a few ways to tell if the claims in these headlines are worth considering
so in today's video we are going to talk about why nutrition studies keep contradicting one another
the difference between correlation and causation and how to figure out which diet is best for you
hey guys welcome back to my channel if you're new here my name is kait i'm a health coach and i post
videos on a high fat nutrient dense way of eating if you like this video please give it a thumbs up
feel free to share and make sure to subscribe make sure to follow me on instagram twitter and
facebook where i shoot new posts every single day now as i said at the start it can be very
overwhelming trying to figure out what to eat with so much conflicting information one day low carb
diets are good for weight loss the next day they don't work and aren't sustainable so which is it
we're going to start off today talking about why there's so much conflicting information when it
comes to nutrition studies then we'll get into how to tell if a source is valid or not and we will
finish off by talking about how to figure out what diet is best for you and if you do like this video
consider sharing it with a friend or in a facebook group who you think would also find it helpful
nutrition study limitations now i am not here to tell you that nutrition science is entirely
corrupt that there is some big conspiracy going on that's not what this video is going to be
about there is actually a few valid reasons why the nutrition studies we read about in headlines
often contradict one another the first reason is that it is simply not possible
to conduct long-term rigorous studies when it comes to nutrition the best types of studies
are experimental studies where researchers are in control of the variables because nutrition studies
have to be done on humans or the best type do at least you can only control people's eating habits
for so long it would be unethical to study someone in a controlled environment for 50 years let alone
10 years or even 5. but that is how long you would need to really figure out what variables of a diet
lead to what health outcomes but because you cannot do this a lot of nutrition studies last
less than six months then there is obviously the issue of finances studies like this are expensive
and the longer they go the more expensive they will be so this is yet another constraint and
then there's the dilemma of funding in order to conduct a study like this researchers need to be
funded but where is this money come from a lot of the times companies will fund a study that relates
to the product they are trying to sell with the hope that the outcome will be in their favor
for example coca-cola has very famously funded scientists who say that our obesity crisis is
due to a lack of exercise and that sugar sweetened beverages play no part at all there are of course
rules in place that are supposed to prevent conflicts of interest like this from happening
but there are also loopholes the point is that researchers are in a dilemma they need funding
in order to conduct these studies but this funding often comes from large corporations
with a vested interest now i am not saying that all nutrition studies are worthless of course
there is definitely value in a lot of them but you just need to know what red flags to
look out for when you come across an article making a big claim the first of which being
knowing the difference between correlation and causation what do i mean by this a correlation
means there's a connection between two or more things while causation means that
one thing caused another sometimes a correlation can be causation but other times not for example
ice cream sales and sunburns are co-related when ice cream sales are up more people get sunburned
but does this mean that eating ice cream puts you at a greater risk of getting burnt no it doesn't
there is another variable which is the weather on hot sunny days people are more likely to be
eating ice cream and also to be out in the sun for longer periods of time but how does this
relate to nutrition as we already discussed it is impossible to conduct long-term controlled studies
when it comes to nutrition but there is another long-term option observational studies these types
of studies look at large groups of people who are living their lives and draw connections between
factors such as their diet and health outcomes the way these types of studies collect data
is through food frequency questionnaires these questionnaires ask participants what and how often
they eat certain foods i'm sure you can already start to see some of the drawbacks
of collecting data through this method one of which being the data is based on self-reporting
participants are asked to remember and accurately record how many serves of a food they had per week
if i were to ask you how many serves of bacon you had per week over the last year do you think you
would be able to give an accurate answer the other drawback is something called the healthy user bias
people who eat healthy are also more likely to not smoke not drink exercise regularly etc
all of these factors are likely contributing to their health so it is hard to pinpoint which one
is leading to the health outcomes because of all these limitations observational studies
can only find correlations for example red meat consumption has been cited in the past as being
correlated with heart disease but as we already discussed correlation does not equal causation
these types of studies are meant to form hypotheses which researchers can then investigate
further through more rigorous trials the problem is that observational studies like this are often
the ones being cited in these flashy headlines and you will notice that these headlines are very
careful with their wording they will use words like linked to or associated with to describe the
connection between food and health outcomes and this is because they know this evidence
isn't conclusive of course you can never be 100 certain when it comes to scientific research
but you can be a whole lot more certain with experimental studies than with observational ones
so the next time you're reading an article making a radical claim check out the source and the
method of the study if it was an observational study definitely take it with a grain of salt
but if it was an experimental study yes that carries more weight but there are a few other
considerations which we are going to talk about now experimental study considerations
just because a study is a controlled trial does not mean the findings are 100 percent accurate
or applicable to everyone there are some considerations that you need to keep in mind
how long was the study if the study was only one week long that really isn't long enough to see any
significant results from a diet change something might be effective short term but not long term
let's use the example of a severely calorie restricted diet where participants were eating
less than 1 000 calories a day this is definitely an effective short term strategy to lose weight
but the catch is that after severe calorie restriction for multiple months metabolism starts
to slow down and you will have to reduce calories further in order to continue to lose weight in
this example a study that lasts for a couple of weeks or a month yes it will yield positive
results but the results are not maintainable was the study done on humans or animals
a lot of studies are done on mice and while this can be a good jumping off point the results do
not always translate for humans how many people were included in the study a study done on five
people does not carry the same weight as a study done on 100 people all other factors considered of
course did the researchers use surrogate markers or endpoints an example of a surrogate marker is
cholesterol levels if a study was trying to determine whether or not eating blueberries
for example reduces your heart disease risk they might look at changes in cholesterol levels
and determine that because cholesterol decreased the risk of heart disease decreased as well
however this might not be directly related and even though cholesterol levels lowered
if the same people still had heart attacks despite this it doesn't really mean anything
has the study been replicated are there examples of other studies with the same findings
if the conclusion of the study is meaningful it should be able to be replicated who was the study
funded by this we discussed earlier of course be wary of a study claiming that eating cereal for
breakfast is healthy if it was funded by kellogg's what diet is best for you if you've made it this
far in the video i applaud you for sticking with me it may seem overwhelming to have to fact check
every nutrition article you read and believe me i totally get that at the end of the day
we know our own bodies best and we can run experiments on ourselves and track our results i
often have people reach out to me saying something along the lines of i have been eating keto for a
year i've lost 50 pounds my blood pressure is now normal i am no longer type 2 diabetic my arthritis
has improved but my doctor is worried about my cholesterol and says i should change my diet
now cholesterol is a whole other topic for another day i do have another video where i talk about why
cholesterol sometimes goes up and ldl specifically on a ketogenic diet so i will link that above if
you want to check it out afterwards but long story short you need to look at the big picture
if you have improved a bunch of health ailments if you have lost a lot of weight if you are feeling
great clearly you are doing something right don't let some flashy headline or story about your mom's
sister's friend failing with keto or any diet for that matter dissuade you if you are feeling great
and seeing results the moral of the story is is that there is so much we still do not know about
nutrition and how it relates to our health the science is not settled on any front because as we
discussed earlier nutrition is extremely difficult to study experiment and tweak to figure out what
works best for you of course blood tests can be healthy but even a lot of the reference ranges are
not applicable to everyone anyways guys that's all i have for you today let me know in the comment
section down below what was the most outrageous nutrition headline you've ever seen your comments
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