Name: Most Metabolism Boosters Are BS
Uploaded: 2020-04-13T16:18:26.000Z
Duration: 12 min 6 s
Description: Thousands of YouTube videos with English-Chinese subtitles! Now you can learn to understand native speakers, expand your vocabulary, and improve your pronunciation...

Thanks to Brilliant for supporting this whole week of SciShow.

Go to Brilliant.org/SciShow to learn more.

Take a stroll into any nutrition store and you'll see displays

stacked to the ceilings with products that claim to “boost” your metabolism.

Whether they're marketed as “Metabol Burn” or “VitaGainzzzz” or something equally

there's one thing that they have in common: They don't really work.

Decades of research show that making any meaningful change in your metabolism

is really hard to do, so a powder or pill won't turn you into a calorie burning machine.

Most supplements can't really boost your metabolism,

and the actual changes we can make to it are pretty limited.

Contrary to what the supplements might lead you to believe,

metabolism isn't just the ability to burn off energy from food.

The actual claims are all over the place,

but in general when a product says it “boosts” your metabolism,

that's code for burning more calories or fat.

but even that process is affected by your physiology, like enzymes and hormones.

they use it as a broader term for all of a cell or body's processes.

Which is a pretty big concept, and not very informative on its own.

So since that's such a broad definition, researchers usually break it down into smaller components.

The biggest slice of the metabolic pie is something called basal metabolic rate,

or BMR, and it's the energy your body uses at rest.

True BMR is measured when the subject is at rest, at a certain temperature,

not digesting food, and not pregnant, because all of those things

can nudge your energy consumption one way or the other.

Fun fact: growing a whole other human inside of you changes your energy needs.

Furthermore, different parts of the body have different metabolic rates.

Gram for gram, your kidneys and heart consume the most calories,

Towards the bottom of that list is muscle and fat.

But no one is advocating taking on an extra kidney to try to raise your rate of calorie burn.

Instead, researchers focus on two tissues that we can tweak: fat and muscle.

Fat, or adipose tissue, is one of the ways your body stores energy long term,

so it makes sense that it doesn't take a lot of energy to store energy.

Muscle, on the other hand, has the opposite job.

When you exercise, it uses quite a bit of energy and oxygen,

but even at rest, its caloric needs are higher than fat.

And sure enough, people with a higher proportion of muscle mass

tend to have higher basal metabolic rates than people with more fat mass.

That is, they burn more calories per gram of body weight even when they're resting.

Now the second slice of the metabolic pie is energy used during exercise, but again, with an asterisk.

Yes, when you exercise, you use a few more calories for a short period of time,

but even a thirty minute workout burns a pretty small number of calories compared to your BMR.

So researchers also look at how exercise affects something called resting energy expenditure,

which is just a more relaxed way to measure overall metabolism than the super-specific BMR.

Multiple research groups have found that aerobic exercise,

whether it's long and slow like riding a stationary bike,

or short bursts of intense exercise like sprinting, all elevate metabolism temporarily after exercise.

Likewise, lifting weights also leaves you with a slightly boosted metabolism after the workout.

And long term, those bulkier muscles are probably what make the biggest difference in your metabolism.

One 2008 study on diet and exercise in overweight women found that resistance training

allowed participants to keep their metabolisms elevated even after the diet,

while the ones who just cut calories ended up slowing their metabolisms.

But even if you're not hitting the gym, you still have the third slice of the metabolic pie:

non-exercise activity thermogenesis, which makes for a neat acronym.

It encompasses all of your day-to-day, moving-around-but-not-exercising activities,

like walking around the house, or doing the dishes, or watering the plants.

That adds up to a good chunk of metabolism, but it varies a lot depending on your lifestyle.

Now this last way our bodies burn calories actually has a lot to do with how we eat calories.

It takes energy to digest, absorb, and get rid of food,

so we call those calories the thermic effect of food.

High-protein foods take a bit more work to digest than others,

so your steak has a higher thermic effect than a bag of chips.

But even something like ice water has a thermogenic effect

thanks to our bodies warming it up, which takes energy.

Now, it's easy to think of our meat sack bodies as simple calorie-burning engines,

but metabolism happens at the cellular level,

which is where supplements might claim their products work.

For instance, after eating and digesting a piece of fruit,

the simple sugar glucose is released into your bloodstream.

This is our bodies' main energy currency.

But it still needs to get into the cell so that cellular machinery can turn it into usable energy.

And it's a big molecule by cell standards, so it doesn't just seep right in.

a hormone that binds to receptors on our cells and shuttles glucose inside of them.

Without insulin, we could still digest food and get glucose into our bloodstream,

but we wouldn't be able to process it into energy since it couldn't enter the cell,

which is exactly what happens in diabetes!

Your body either can't make enough insulin, or has trouble importing enough sugar into cells.

But glucose isn't the only nutrient our body uses for fuel.

And chances are that if a product is marketed as a metabolism booster,

Now, fat is utilized in a complex chain of chemical events that I'm not gonna explain here.

But at rest, your body typically doesn't use fat for energy.

whereas the glucose that's floating in your blood is ready to use right away.

Before resorting to breaking down fat, your body will typically tap

the stored glucose in your muscles and liver, called glycogen.

And to complicate things further, your body never only uses fat or only glucose as a fuel source.

So hopefully you're starting to see that your metabolism has lots of moving pieces to it,

and if a product says it can change your metabolism, that's a pretty bold claim.

Despite the lack of evidence backing them, pharmacies still keep these products in stock,

even as some researchers have voiced concerns about their safety.

These products are available over the counter, at least in the US,

but they're not regulated as tightly as proper pharmaceuticals.

Subtitles ListPlay Video

Most Metabolism Boosters Are BS

process

deprivation

metabolism

evidence