- If you've watched my videos before,
you'll know that I'm a fan of low-carb diets,
having lost 30 kilograms in 2016 to reverse my own obesity.
So you'd probably think I'm going to say yes,
of course carbs cause weight gain.
Wouldn't it be nice if it was that simple?
The notion that carbs cause weight gain
seems to fall pretty fast when you speak to somebody
who regularly eats giant bowls of pasta
whilst remaining stick thin.
And I think we all know someone like that.
So, if it's not carbs that make us fat,
then it must be eating too many calories, right?
In that case, it's just a case
of creating a calorie deficit and you'll lose weight.
But if eating less and moving more worked as advertised,
weight loss would be easy
and we wouldn't have an obesity epidemic.
So which is correct?
Well, there's been some recent developments in this area
which help shed some light on the issue, so let's find out.
(upbeat rock music)
The debate over what causes weight gain has raged for years.
There are two main theories about why we gain weight
and both suggest different solutions
to how we should go about losing weight.
The first is the energy balance model
which states if you eat more calories than you burn,
you'll gain weight,
irrespective of where those calories come from.
The second is the carbohydrate-insulin model
which says no, the source of those calories is important
and the consumption of carbohydrates
is the primary driver of weight gain.
AKA, carbs make you fat.
We're going to look at both of these in this video,
but I want to stress one thing from the outset.
Neither attempts to fully explain weight gain.
Many other factors may also contribute,
for example, education levels, food literacy,
media consumption, exposure to food advertising,
social pressures to consume various foods,
the social acceptability of obesity, levels of employment,
female employment, the type of employment,
and a tendency towards increasingly sedentary jobs,
cost of food ingredients, cooking skills,
perceived lack of time for cooking,
the availability of convenience foods, the smoking rates,
alcohol consumption, levels of recreational activity,
peer pressure, the use of medication, stress,
emotional eating, access to opportunities to exercise,
the cost of physical exercise, genetics,
and breast feeding to name just a few.
We're talking about the central premise here.
For example, here is the British obesity system map
which attempts to piece
all these different factors together.
It's complicated, right?
But has energy balance at the center
of all these other factors listed contributing to it,
but at no point mentions the impact
of dietary carbohydrate consumption.
The carbohydrate-insulin model wouldn't eliminate
all that other stuff around the outside,
it would just replace the middle bit.
So we're talking about the central premise today,
not every single factor.
Let's start by looking at the energy balance model.
You're probably very familiar with this
as it's the one that has been dominating
the public health message for many years now.
It states that a calorie is a calorie
and excess calories will cause weight gain
regardless of whether those calories come from proteins,
fats, carbohydrates, or alcohol.
The energy balance model implies that over consumption
of highly processed, energy-dense foods
is the cause of obesity
as well as people living increasingly sedentary lives.
It suggests that all you need to do to lose weight
is create a calorie deficit
by simply eating less and moving more.
Suppose it was this simple,
indeed, obesity should have been an easy condition to cure.
Unfortunately, rates of successful weight loss
through calorie restriction are shockingly low.
If you've ever been obese or overweight,
I want to ask you a question.
Have you ever managed to maintain weight loss
beyond three months by calorie restriction alone?
I'm going to pin a comment at the top of the comments section.
Just take a second to answer yes or no.
It's not exactly a scientific survey,
but I'd be willing to bet
that there will be more nos than yeses.
The public health message
that we need to eat less and move more
has been a catastrophic failure
as evidenced by the increasing levels of obesity.
Typically, a calorie-restricted diet
is low-fat because gram for gram
fat contains more calories than carbohydrates.
Therefore, we can consume
a larger quantity of food for fewer calories.
And this message has been supported
ever since the introduction
of the low-fat dietary guidelines in the 1970s.
Yet, in the most extensive long-term study
of its type ever completed,
nearly 20,000 women assigned to a low-fat diet
for seven and a half years lost less than 0.4 kilograms.
That's not even a pound.
And here's the thing,
we all know that calorie restriction works initially,
but after a few weeks, your body fights back.
The energy balance model fails to consider
that your body senses it's being calorie restricted
and it mounts a response.
The hormones that control your hunger start to increase
and you begin to feel more hungry.
Your metabolism starts to slow down
and so you conserve energy.
It gets harder and harder to stick to the eating plan
or to go out for that run
and you probably feel miserable and starving.
The energy balance model makes weight gain and loss
a physics problem, energy in and energy out,
and fails to address the biology
of how our bodies actually work.
The worse thing about the energy balance model
is that it puts the responsibility for failure
back onto the individual.
It says that it's your fault
if you've failed to lose weight.
You should have managed to cut your calories more.
You should have exercised more.
You lack willpower.
So why does this message persist?
I love this quote by Henry Mencken.
"There's always a well-known solution
to every human problem, neat, plausible, and wrong."
And I really think that applies here.
Firstly, I think that public health organizations
love to give out a simple message
and they don't come much more straightforward
than eat less, move more.
Secondly, because many of us have experienced
that it works in the short term,
we have this instinct that it must be true.
It's easier to blame our willpower
than to challenge the status quo.
But, perhaps more cynically,
it's a message that suits fast food and soft drinks brands
because it says you can eat what you want
as long as you exercise enough.
It puts the responsibility on the individual
and takes it off the corporations.
Brands have spent billions promoting this message
through clever marketing campaigns
such as associating their products
with major sporting events.
They've also sponsored scientists to push this message
in the scientific literature
and to sit on boards that decide public health policy.
Follow the money.
Now let's now look at the alternative,
the carbohydrate-insulin model.
The carbohydrate-insulin model of weight gain
suggests that over consuming foods high in carbohydrates,
especially those that the body absorbs rapidly,
causes fat storage.
It suggests that the reason for this
is that carbohydrate consumption
stimulates insulin production by the pancreas.
This signals to our fat cells to take up whatever glucose
is not immediately required for energy
from the bloodstream and turn it into fat.
Already, we can start to see how this is more aligned
with how our bodies actually work
and we have numerous examples
showing the effect of insulin on weight gain.
When we start someone on insulin injections for diabetes,
one of the significant side effects is weight gain.
Similarly, whenever we prescribe medications
that stimulate the body to produce more insulin,
they result in weight gain.
Occasionally, people develop tumors that secrete insulin,
called insulinomas, which cause weight gain.
And then if we look at it
from completely the opposite angle, in type 1 diabetes,
when the pancreas suddenly stops producing insulin,
patients present with rapid weight loss.
All of these examples highlight the important role
that insulin plays in promoting weight gain.
It suggests that the solution to the issue of obesity
is to restrict the intake of carbohydrates.
This low-carb diet results in lower insulin levels
and creates conditions in the body where we can lose weight.
And it works, it's worked for me,
it's worked for my clients, but more importantly,
we've got loads of high-quality scientific evidence
showing that low-carb diets are superior to low-fat diets.
There is a complete list of all these studies
on the Public Health Collaboration website
if you'd like to go and look at them for yourself.
So why isn't this routinely accepted as the status quo?
Even though it makes a lot more sense
and is more aligned with our biology
than simply restricting calories,
people frequently criticize this way of thinking
about weight gain and weight loss.
Well, on the face of it, there are a few problems.
There are numerous examples of populations
with high white rice consumption yet low levels of obesity.
This is known as the Asian Paradox.
These populations are frequently used as a reason
why the carbohydrate-insulin model must be false.
So why do these populations
usually have relatively low levels of obesity?
There are multiple different interpretations of this.
Remember, many different factors can impact obesity levels.
These populations are typically
subsistence farming societies
with exceptionally high physical activity levels.
This may offset the impact of high carbohydrate consumption.
Additionally, there have been plenty of studies
which have compared high-carb diets against low-carb diets
which show that when you correct for calories,
there's no difference in weight loss.
These studies are fascinating
and I always have people in the comments of my videos
who roll out these studies
to justify why low-carb diets are not superior.
But the vital thing to remember
is that these are calorie-controlled studies.
What these studies don't tell us
is the effect on our appetite.
In the real world, we're not controlling for calories
as we do in scientific feeding studies.
Because they control for calories,
these studies fail to understand that low-carb diets
have a significant effect on hunger.
Ghrelin is a hormone produced primarily in the stomach
which signals to our brains that we're hungry.
Ghrelin levels are significantly lower
in those on low-carbohydrate diets.
Similarly, leptin, a hormone produced by our fat cells,
is also found to be lower
in those on a low carbohydrate diets,
suggesting an improvement in sensitivity to this hormone.
Then we have very low-carb or ketogenic diets,
where the body begins to produce ketones.
This alternative fuel source may inhibit appetite directly.
The experience of myself and many others
is that they're less hungry when on low-carb diets
and, therefore, naturally calorie restrict.
Because we have low insulin levels,
our fat stores can give up their energy between meals
like they're supposed to.
People often drop from three meals a day plus snacks
to two or even one meal a day
simply because they're less hungry.
This is a game changer.
And yes, there are several other criticisms
of the carbohydrate-insulin model
which I'm not going to go into in this video
because they're very academic.
But if you'd like to learn more,
I will point you in the direction
of a fantastic review article by Doctor David Ludwig.
David is a professor of nutrition
at the Harvard School of Public Health.
He authored a very detailed 2021 review
in The American Journal of Clinical Nutrition
that addresses these concerns.
So for those of you who want to dig deeper on this topic,
I'll put that link in the description
along with all the other references
that support what I'm saying in this video.
The carbohydrate-insulin model, by its very name,
mainly looks at the role
of glucose in triggering an insulin response.
But glucose isn't the only carbohydrate we consume.
We need to look much more closely at the impact of fructose,
AKA the fruit sugar here,
because it helps us to explain
some of the shortcomings in the carbohydrate-insulin model
that I mentioned earlier.
For many thousands of years,
humans consumed fructose
amounting to between 16 and 20 grams daily,
mainly from fresh fruits.
More recently, Westernization of diets
has resulted in significant increases in added fructose,
leading to typical daily consumptions of 85 to 100 grams.
This represents a fivefold increase
in what we used to consume.
Most of that has come from added sugar
in the form of sucrose, AKA table sugar,
and high fructose corn syrup,
but also fruit juices and smoothies.
Sugar is everywhere these days.
Sweet foods and many apparently savory processed foods
contain a surprisingly large amount of sugar too.
Crucially, that big bowl of pasta that your friend can eat
without gaining weight contains starches.
The same thing is true for that white rice
in the Asian Paradox example.
Starches are broken down by our digestive system
to glucose but not fructose.
Crucially, sugar provides us with large amounts
of both glucose and fructose
in a form which is rapidly absorbed by our bodies.
The energy balance model suggests
that sugar causes weight gain
simply because of the empty calories that it provides.
But that doesn't fit in with our understanding of how sugar
actually impacts our bodies.
We've learned a lot about this in the last decade.
Firstly, we must understand that fructose
is metabolized differently from glucose.
The whole body can metabolize glucose.
In contrast, fructose is almost exclusively metabolized
in the liver where it's turned mainly into fat.
The fat that we make in our livers from fructose
tends to be stored around our abdominal organs
which is very harmful
and strongly associated with heart disease.
Continued fructose consumption
overwhelms the ability of the liver
to export that fat that it makes,
leading to fat becoming trapped within the liver.
This is a condition known as fatty liver disease.
We know that 70% of overweight people
and 75% of people with obesity have fatty liver disease.
A liver with fat stored in it is unhappy
and responds by coming insulin resistant.
Insulin resistance is when our bodies don't respond properly
to the hormone insulin.
Our cells need more than the usual amount of insulin
to get the same response as before.
Therefore a key feature of insulin resistance
is persistently elevated levels of insulin.
We've already looked at the role
that insulin plays in weight gain,
and now we find ourselves in a situation
where we've got a lot more insulin within our bodies.
These elevated insulin levels keep our bodies
in fat storage mode so any carbohydrate intake from our diet
is readily stored as fat.
Insulin levels remain elevated between meals
when they should be low.
This means we can't access our stored fat for energy
like we should be able to.
Excess fructose has started the problem
but once insulin resistance is established,
we have issues processing glucose too.
Over time, the problem can become so severe
that no matter how much insulin you produce,
your body can't control your blood glucose levels.
They start to climb and cause damage.
That's type 2 diabetes.
And you might ask why have we suddenly started
talking about type 2 diabetes?
This is a video about whether carbohydrates
cause us to gain weight.
Well, that's the point.
Insulin resistance underpins both of these diseases.
They're on the same spectrum.
Some people even call them diabesity.
So the question I set out to answer
at the beginning of this is, do carbs make you fat?
When we're metabolically healthy,
carbohydrate consumption
doesn't typically cause weight gain.
This is typically when we're young, active, and healthy,
when our bodies haven't developed insulin resistance.
Insulin is working as it's supposed to.
It surges up after a carbohydrate based meal,
then drops back down,
allowing our bodies to access stored fat between meals.
In the beginning, I mentioned that person
who can seemingly frequently eat large bowls of pasta
without gaining weight.
Well, they almost certainly
haven't developed insulin resistance at that point.
In those with healthy metabolisms,
calories in versus calories out
appears to work as advertised.
But unfortunately, in the modern world,
that doesn't last for long.
The amount of fructose we're consuming from sugar
eventually takes its toll on our metabolism
and we develop insulin resistance.
For those who are already metabolically unhealthy,
and that's the overwhelming majority of adults
and an ever increasing number of children,
the development of insulin resistance
means that carbohydrates will cause weight gain
as we effectively become intolerant to them.
Essentially, the more metabolically sick we get,
the more the impact of carbohydrates
on our bodies becomes apparent.
And we are sick.
It's estimated that 75% of adults in the USA
are metabolically unhealthy.
Here in the UK, 75% of adults over 45 are overweight.
And half a billion people have diabetes, including in China.
Remember we talked about the Asian Paradox?
Well, things have significantly changed
over the last few decades.
In modern-day China,
there is an epidemic of obesity and diabetes
caused by a significant Westernization of the diet.
So, for me, the carbohydrate-insulin model
represents a much better explanation
of why we gain weight than the energy balance model,
especially when we consider the negative impacts
of fructose from excess sugar.
Importantly, we've got a ton of evidence
that low-carbohydrate diets work,
which is why I'm such a big advocate of them.
But the other thing that is consistently shown
to improve people's weight loss results
is getting proper support
when trying to implement these changes.
It's one thing knowing which hill you need to climb up,
it's another thing actually climbing up it.
I've been helping people with this since 2016
and I've come to realize
that there is much more to this lifestyle
than simply cutting carbs.
It's why I run support program
called The Carb Dodging Challenge every few months.
In this eight week program,
we support you through all the aspects
of implementing this in your life
so you can get off to the best start possible.
I'm delighted to share
that our clients consistently get amazing results.
If you'd like to learn more about it,
please visit carbdodging.com/challenge.
I'll leave a link to that in the description.
Thank you for watching this video.
If you found it helpful, please give it a thumbs up.
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and hopefully, I'll see you in the next one, bye-bye.