- How many calories do we really burn
when we're out riding our bikes?
Well we know it's a great way of losing weight,
so the short answer is, probably quite a lot.
But how do we really calculate it?
How do we know how many carbs we need to consume
while out riding, so we don't run out of energy,
and hit the wall?
- Yeah. Put simply, a calorie is a unit of energy.
So the more calories in the piece of food,
the more energy that it contains.
And to put simply again, we can work out
exactly how much energy it takes
to ride at a certain pace.
(funky music)
- Pedalling a bike requires power.
Which is measured in watts.
You can roughly assume that producing one watt of power
for an hour will burn four calories.
It doesn't sound like much,
but so, if you get 10 miles per hour on a flat road,
requires about 40 watts.
15 mph about 100.
And 20 mph on a flat road, about 210 watts.
So riding 10 miles in an hour
requires 140 calories.
15 mph 350 calories,
and 20 mph about 700.
Knowing exactly how many calories you're burning
is going to require some fairly specific technology.
Which normally means a power meter,
such as the one that Matt and I are using on today's ride.
However, they are quite a significant investment,
so an alternative is to use a flat road
to give you a rough idea of calories burned.
However, as soon as you start going uphill or downhill,
or you have a big tail wind or head wind,
that's going to vary quite considerably.
Instead then, you could get a rough idea
from your heart rate.
- Yeah, that's a really long established method
that takes into account your age, your weight,
and how long you've actually been exercising for.
Throw into the mixture average heart rate,
and you can get a really good idea
of how many calories you've burned.
- So, to give you an example,
I am 36 years old,
I weigh 70 kilogrammes,
and to average around 20 miles per hour or 210 watts
on a pan flat road, it only requires
an average heart rate for me personally
of about 140 beats per minute.
Crunching those numbers in the calorie calculator,
and it comes out at 770 calories per hour.
- So it's pretty clear then,
there's some inaccuracy here.
In fact, there's quite a lot of inaccuracy
across the board with all of these methods.
But, in particular, heart rate.
Take for example, comparing one person to the next.
Some people have a really low heart rate,
compared somebody else,
but that would have no bearing on their fitness whatsoever.
And then you've got to look at your own heart rate.
It could be changed alone depending
on your level of fatigue, or even,
the temperature of your body.
But what about power?
Surely that is actually measuring an output.
Well yes, it is, but in order to
calculate calories from power,
there is an assumption about the efficiency of your body.
Meaning, how many calories are wasted
when producing that power.
And the reason that it's only an assumption,
is because people's efficiency varies,
by up to 30 percent.
- To put that into context, that's the difference
between needing 850 calories
to cycle at 200 watts for an hour,
or just 600 calories.
That's the difference in needing three extra
of these energy gels, every hour.
Now there's one last element to complicate things.
You don't stop burning calories
when you climb off your bike.
You burn calories just to stay alive of course,
but certain types of exercise
raise your metabolic rate,
effectively making your body burn more calories,
even when you're resting in bed.
That's because high-intensity exercise
causes muscle damage, and that takes energy to repair.
- So, whilst you might burn 700 calories
by riding 20 miles in one hour,
you might find that this effort makes you burn more calories
for the subsequent 24 hours as well.
And if this is really what you want,
high intensity intervals are what you need.
If you ever want to measure exactly
the amount of calories that you burn while cycling,
you're gonna need to know the quantity
and the types of gases that you breathe out,
and the relationship between oxygen and carbon dioxide.
And as you can imagine, that would take
some pretty specialist type of equipment,
most likely taken place in a lab.
And let's face it.
Do you really need to be that accurate?
- Probably not, but knowing roughly
how many calories you're expending whilst you're out riding
is going to allow you to know how much you need to eat,
or how much energy drink you need to consume,
in order not to run out of energy
whilst you're out on your ride.
And actually any ride over 90 minutes
is going to require some kind of carbohydrate consumption,
even if your main aim is to lose weight.
And if that's the case, it's restricting calories
off the bike, that's going to be more beneficial.
- So you should go and have some cake?
- Yeah. Anyway.
- If you haven't already subscribed to
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And you can do that by clicking on the globe.
- Yeah, and if you would like to do
some high-intensity indoors, on your indoor trainer,
we've got the perfect video for you just down there.
On the other hand, if you'd like to know
where is the best place to consume food
whilst you're out on the bike,
you can find that just down there.
- And tip, it's probably a cafe.
- No, actually on the bike.
- Oh.
- Alright.