Losing weight is hard and unfortunately your
body is sabotaging you every step of the way. Your body is a biological machine that follows
the laws of thermodynamics and needs energy and raw materials to stay alive, which is why you eat.
The energy from food is measured in calories and you need a certain amount to power your internal
machines. Your brain thinks, your heart pumps, your gut digests, your immune system immuns.
And you contract your muscles to move around. The harder a movement is, the more calories you
burn. An hour of walking burns about 260 calories, moderate swimming 430, biking 600, running 700. If you eat more calories than you burn, your
body stores them mostly in the form of fat. One kilogram, or two pounds of fat is about
7000 calories. Seems simple. To lose weight, you have to burn more than you eat,
so fat is turned back into energy. There are two ways to do this: Eating less – which
we'll cover in another video – and burning more, say by moving around aimlessly, also called
working out. We also get told early on that exercising is healthy somehow, so working
out should kill two birds with one stone. Unfortunately this doesn’t exactly work out. It's one of these frustrating experiences
where you do what you think is right only to not see the results you deserve. In
reality exercising is a bad way to burn fat. And until recently we fundamentally misunderstood
what moving around a lot does to our bodies. The Myth of the Workout A few years ago scientists began to compare
populations in industrialized societies, which sit a lot, to hunter-gatherer
communities, who move around a lot. The Hadza people in Tanzania walk an average of
9 km a day to find wild plants and hunt animals, dig for tubers, climb trees for honey,
or collect water. They can move more in a single day than an office worker in a week.
So of course, they burn more calories, right? But it turns out that the Hadza burn the same
amount of calories per day as a typical person in an industrialized country: around 1900 for
women and around 2600 for men – which doesn’t make sense at all. It’s also not their genes, since
it’s the same for other hunter gatherer tribes. So the confused scientists looked at similar
measurements in individual countries. It got even stranger: Active people who work out
regularly do burn more than inactive people. But only very little, often as low as 100
calories, the equivalent of a single apple. For some strange reason, the amount
of calories you burn is pretty much unrelated to your lifestyle. Per kilo of
body weight, your body has a fixed calorie budget it wants to burn per day. Sure, if you
want to gain muscles by pumping iron, you also need to eat more to build and sustain them or
your new muscles wither away. But in total, your body keeps your calorie budget
per unit of you, pretty stable. And to make matters worse, if you want to lose
fat your body sabotages you in small and big ways: First of all, when you begin to work out
regularly, maybe going for a run in the morning, your body may subconsciously make you move
less when you don’t pay attention. Maybe you take the elevator instead of the stairs, you
sit more when you meet your friends or you sleep longer – largely balancing out your burn
again, preventing you from burning much fat. You can overcome this temporarily: If
you do actually change your life after sitting around for years and suddenly
start working out without eating more, this is a shock to your system. You actually
do burn more calories and lose fat – so you can lose a few kilos or pounds through exercise!
But this is very short-lived. Your body adapts and burns fewer and fewer extra calories each day
until it restores its original calorie budget. After a few months you burn basically
the same amount you did when you didn’t work out. Bizarre. And now we are getting to
the actual reason why exercise is healthy. Why Your Body Is Sabotaging You So your body has a hardwired activity
budget per day that it wants to stick to. This setting evolved when humans had to
move a lot. Not because they wanted to, but because they had to find food for survival. But
when food is abundant and exercise is voluntary, what does your body do with the energy
that you are not using to move around? We are simplifying a lot here and this is
relatively new science, but in a nutshell: There are many different systems in your
body trying to do their job as well as possible. And if there’s extra energy, they
seem to use it. Unfortunately this is bad. When your immune cells detect injuries
or infections, they trigger inflammation. Fighter cells, alarm chemicals and fluids
flood into your tissue. This is crucial but it also causes damage, so it needs to be
cleaned up quickly or it can become chronic. And chronic inflammation is one of the
major contributors to many serious diseases, from cancer to heart failure. If your
immune system is on a tight budget, it has to be efficient with inflammation – with
lots of free calories though, it over commits. Another thing is that your glands produce
hormones you don’t need. Like cortisol, the stress hormone, which triggers your fight
or flight response. Crucial for survival, but if you have too much of it you get, well,
very stressed, all the time. Chronic stress is a major cause for a bouquet of health issues
including your mental state. For our ancestors who moved a lot and had to deal with sudden
bursts of activity, fleeing from a lion, attacking that bison, this cortisol was crucial
– but if you live a modern, sedentary lifestyle your body is ready for action that doesn’t
happen, hurting itself in the process. Your body evolved to move regularly and is fine
tuned to a certain base level of activity. If this activity is missing it still uses almost the
identical amount of energy, just on stupid stuff. This is why you burn almost the same amount
of calories whether you work out or not - by working out you are not doing anything extra, you
are doing what your body is literally made to do. Working out is not a magic bullet, but it seems
to restore an internal physical balance that seriously affects your body. And this is also
why regular exercise is so incredibly healthy, the evidence is incredibly clear here. It
reduces chronic inflammation and stress, it is good for your heart, may ease depression,
and makes you live longer and better. Movement is not really made
to burn your fat though. Why Humans Are So Hungry When your ancestors evolved, they had to work
hard for calories. Sometimes it would be easy and they could afford to chill out quite
a bit. But in hard times they had to move quite a bit to feed themselves, walk longer
to find prey, or dig longer to find tubers. If extra movement burned more calories this
would lead to a spiral of starvation. The less food you find, the more energy you need
to find food – which doesn’t even fill you up, because you moved more. It’s like
taking on more debt when you are in the red. It works for a while, but then you
go bankrupt and die. So for your ancestors, being able to move a lot without burning
extra calories was a matter of life and death. Ok. But this means the obesity epidemic of the
modern world is not primarily caused by laziness, but by overeating. Humans evolved
to be mad for calories. Because of our extremely hungry brains,
and our extremely useless kids. Kids are cute but unlike other species,
human kids have to be fed and cared for by adults for years before they become
even remotely useful. Because the human brain not only eats up about 20% of all
our calories at rest – twice as much as our closest ape relatives’ – it also takes
a lot of time to develop through playing, learning and honing social skills –
all the things that make us human. Our species is so extremely calorie-expensive
to maintain that we became super-efficient calorie harvesters. 5 hours of human hunter
gatherer foraging yields between 3,000 and 5,000 calories, while our ape relatives
get no more than 1,500 in the same time. And we became so good at calorie harvesting
precisely because of our big brains and years of social skill training. In a typical
ancestral tribe some members would spend the day searching for plants, others hunting
or gathering honey, others nurturing kids. And at the end of the day, we’d share the
calories so that no one would end up hungry. Being frenetic calorie harvesters seems to
be deeply part of what makes us human. It's not a bug, but a feature. But today it
seems as if that feature has turned on us – we can’t stop overproducing food,
and overeating. If you want to lose fat, food is the answer. We’ll
cover diet in the next part. So to conclude: You'll probably not lose
nearly as much fat by working out as you hoped, but you will do something more important:
give your body balance and make you more resilient and prevent or delay many of
the diseases that will make your life miserable so you can enjoy a higher
quality of life, for much longer. But physical fitness is only half the equation.
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