Lesson video

Hi there.

Welcome to this lesson called "Energy Use" from the Health and Wellbeing Diet and Nutrition Unit.

It's Mr. Brim here, and we're gonna look at some really important information today about how what we eat and we drink and how we then go and burn calories during the day has a major impact on our health and wellbeing.

Some really useful information for everybody to know, not just those people who are interested in sport and physical activity.

Let's begin.

Alright then, so by the end of today's lesson, you should be able to explain how energy is measured and what impacts energy expenditure and energy balance.

Let's have a look at our key words: calories, calorie consumption, energy expenditure, weight and health.

Pause video here if you want to have a look at those definitions.

And it's a two-part lesson, the first of which is called understanding how we expend energy.

Okay, so I hope you knew this already, but we all need energy to live.

We're gonna learn a lot today about energy.

Even if we just rested all day long, our body needs energy to keep us alive and do important things such as keep our heart beating, maintain our body temperature, keep the brain functioning, and for growth and repair.

So even if we didn't do and anything, we just lay in bed all day long, our body would still need energy to do those four functions and more.

Now, the energy required just to keep us alive and do those things we've just seen on the previous screen is called your basal metabolic rate shortened to BMR. Now, everybody has a different BMR because everybody is different.

"What factors do you think affect someone's BMR," wonders Alex.

What do you think about that? Well, your BMR is dependent on your gender, your height, your age, and your weight.

All those four things combined result in you having your own BMR, which is different from everybody else.

For example, here we have two of our characters.

And Jun, who is a 15-year-old boy, 170 centimetres tall and weighs 57 kilogrammes, his BMR would be 1,583 calories per day just to keep him alive.

Now, calories, this is the first time we've come across this word in this lesson, but I'm sure you are familiar with the word, they are the energy units or the units used to measure energy, and it's also often shortened to Kcal.

If you look at nutrition labels on foods, you probably see Kcal.

And how about Sofia? Sofia is 15 years old, same as Jun.

She is 162 centimetres tall and weighs 53 kilogrammes.

Her BMR is 1,307 calories per day.

So as you can see, more than 200 calories difference.

Because Sofia is slightly shorter and weighs less, her BMR is less than Jun's.

Here's some more examples.

Keely Hodgkinson is 22 years old at the time of writing.

She's 170 centimetres tall and weighs 58 kilogrammes.

So her BMR is 1,372 calories per day.

Jude Bellingham is currently 21 years old, 186 centimetres tall and weighs 75 kilogrammes.

So taller, heavier, and also he is a male rather than a female.

How does that affect his BMR? Well, his BMR is 1,813 calories per day, just under 500 more per day than Keely Hodgkinson.

So we're seeing here, aren't we, how different genders, heights, weights, et cetera, affect people's BMR, the amount of energy we need just to keep us alive every day? So quick check for understanding.

Which of these will affect someone's BMR? So A, your age, B, your activity levels, C, your height, or D, your job? Well done if you said A and C.

Your age and your height will affect your BMR. Remember, this is the calories we need to keep us alive and everybody has a basal metabolic rate.

We're not talking about the calories we need then to go on and do activity.

So your activity levels in your job are calories on top of your BMR as we'll find out shortly.

We don't spend our entire day just resting or I wouldn't imagine that many people do.

So almost all of our everyday activities involve movement and so require energy for us to perform, including walking, brushing your teeth, eating.

All these everyday activities need calories because they all involve movement of some sort.

And so you are using energy to perform all these actions.

On average, all the calories you expend during the day, you burn or you use up, but we're gonna use the word expend, during the day from your BMR and your everyday activities will total up to approximately 2,500 calories for men, and 2,000 calories for women.

Now, Sam says, "There's one important way of expending energy we haven't discussed yet.

What do you think it is?" Physical activity, of course.

This is a PE lesson, isn't it? And so we are interested in physical activity.

All of your favourite sports and physical activities require energy to perform and each one of its own energy requirements, depending on factors such as how long you spend doing it, also called the duration, and how intensely you do it, the intensity of the exercise, also your personal measurements, such as your weight.

So how long you spend doing it.

Let's think about the duration.

Jun's back with us.

And if Jun runs for 30 minutes at six miles per hour, he will expand around 225 calories.

If he runs for 60 minutes at the same pace, he will expend around 550 calories.

Does that make sense? So the longer you do something, the more calories you're going to burn, even if you do it in exactly the same way.

How about intensity? If Sofia runs for 60 minutes at six miles per hour pace, she will expend around 470 calories.

What's gonna happen if she does it for the same amount of time, but more intense at a faster pace? Well, if she did that same 60 minute duration, but this time more intensely at 10 miles per hour pace, she will expend around 730 calories.

So much more calories within that same duration of time because the intensity is higher.

How about your personal measurements? Well, if two people did the same 60 minute aerobics class, so they do exactly the same movements, a person who weighs 70 kilogrammes would expend around 460 calories.

But a person who weighs 93 kilogrammes would expend around 600 calories.

So the higher weight has led to them burning more calories.

Their heavier weight means that they have to expend more energy to move their body in the same way as somebody who weighs less.

Now, all these factors to consider mean that knowing how many calories you've expended in a day is really quite difficult to calculate.

And people are increasingly using technology, such as smart watches to help them understand their energy expenditure.

So smart watches have a good go at calculating how much energy you have expenditure during the day, generally using your heart rate as an important measure to understand just how active your being and how long and how intense your activity is.

True or false: calculating energy expenditure is a complicated task due to so many factors that contribute to it? That's true, isn't it? And why is that? Well, knowing exactly how much energy you used in a day requires you to know your BMR, the energy expended in your everyday activities, plus any energy expended in physical activities, including the duration and intensity of your exercise.

This is why people are increasingly using technology to help calculate it such as smart watches.

Well done, if you said true.

Here's the task for this first section on energy expenditure.

Here are two days in Jacob's life with his energy expenditure itemised.

Here's Monday.

So his BMR is 1,600 calories.

His morning routine is 60 calories of energy.

He does a 30 minute walk to school.

That took 180 calories.

His school day included a PE lesson.

And overall, he expended 450 calories in his school day.

He then walked home from school, which is 180 calories.

He then had basketball practise in the evening, 350 calories.

He did his homework and dinner, which was 80 calories.

And that was the end of his day.

How about Tuesday, the next day? Quite a different day for Jacob.

Let's have a look.

Well, of course, his BMR is exactly the same.

Nothing's changed in his gender, his height, his weight, or his age in one day.

And so his BMR is exactly the same.

His morning routine was also the same: 60 calories.

Over this time, he got a lift to school in the car, and so sitting in the car expended just five calories.

His school day didn't have a PE lesson.

He was sat down in all of his lessons, and so just 150 calories expended during the school day.

He also got a car ride home from school, which is five calories.

He sat at home playing video games for the evening.

That was 70 calories.

And he did some homework and had his dinner, which was 80 calories.

Question for you is can you calculate the total expenditure for each day? And then once you've got those two figures, write a paragraph which outlines any major differences between the two days.

Pause the video, and once you've done that, come back to me, and we'll have a look at how Jacob's two days differ.

Okay, so the first part of the task was to calculate how many calories Jacob expended during the day.

So on Monday you should have come up with a total of 2,900 calories.

And on Tuesday 1,970.

Hopefully, you've got the same as me on that one.

Now, okay, we asked you to write a paragraph comparing Jacob's two days.

Things you might have said were, well, there were several differences, weren't there, between the two days, which resulted in a difference of nearly 1,000 calories expended by Jacob? On Monday, he was really, really active.

He had his PE lesson and he had basketball practise.

And those both used up a lot of calories.

But on Tuesday he was much more sedentary.

He didn't have PE.

When he got home, he played video games, as opposed to going to basketball practise.

There was also a big difference in how Jacob got to and from school with walking expending much more energy than going in the car.

I think what we've seen there with Jacob's two days is just how much our activity during the day affects how much energy we expend, how we choose to commute to school or to work has a major impact with Jacob burning so many more calories because he walked to school, which is of course gonna be much better for his health as well, than getting a lift in the car.

When he had PE lessons and physical activity in the evening that burned so many more calories than sitting around playing video games.

So some major differences in the two days and nearly a thousand calories difference in how much energy he expended.

Lots to think about there I think.

Second part of the lesson is called understanding energy balance.

Now, we know a little bit more about how we expend energy.

Let's think about how we can balance the energy.

So here's Jacob again, and we've just seen this Monday routine.

His question to you is, "Where will I get the energy to do all this from?" Where he expended 2,900 calories, his question to you is where is he gonna get the energy to do this? Okay, now I'm sure this picture gives you a good indication if you didn't already know, but I'm sure you did, that energy comes from and calories come from the foods and drinks that we eat and drink, that we consume.

So for example, if we ate an average size apple, it would provide us with around 90 calories.

So the balance of energy through calories expended, as we've already seen with Jacob and the calories consumed, has a vital impact on things like how energetic you feel, your body composition, and your health and wellbeing.

Let's look at that in a little bit more detail.

Okay, so one way to think of it is like a set of scales, as Izzy rightly says, and so if we think of the scale as having on one side, the amount of energy going in or the amount of energy we consume, and on the other side the amount of energy that we expend or the energy going out, it will then seesaw depending on how much each total up to.

So if the calories we consume are the same as the calories we expend, the body has enough energy to satisfy your BMR and perform all the tasks that you do during the day.

That's what we call an energy balance.

So energy expended and energy consumed are the same.

It's an energy balance.

"But what will happen," asked Izzy, "if you consume much more energy than you expend?" You can see here the scale is tipped in favour of energy in.

There's more energy in than energy out.

What will happen in that case? Well, you will have something called a calorie surplus, surplus meaning more than you need or some leftover.

Plenty of energy for BMR and your tasks, but also some leftover.

So having an occasional calorie surplus won't have much impact.

Maybe you go to a party and you eat loads of food just for one day, and you end up with a calorie surplus for that day.

It's not going to be the end of the world.

It's not going to have much impact.

However, if you are regularly and consistently in calorie surplus, so sort of almost every day you are in calorie surplus, those excess calories will be stored as fat.

And what does that lead to? Well, then your body weight will increase.

If that continues to happen on a consistent basis, then you have the risk of being overweight and then obese.

And there are many associated health issues with being overweight and obese, such as developing type two diabetes.

Just to check for your understanding, which of these shows a calorie surplus? Is it A, B, or C? Well done, if you said B.

Okay, what we can see there is that there's more energy in than energy out.

The scales have tipped in favour of energy in, and, therefore, that's a surplus, isn't it? Expending more energy than you consume is called a calorie deficit.

The opposite, okay? If the deficit is too great, you may not satisfy your BMR. We can see the scales have tipped here, but what are we gonna have on either end? Hopefully, you understand this by now.

We would see a small amount of energy in and a large amount of energy out.

Okay, that's created that deficit, meaning you didn't get enough.

So not eating enough food will also have a negative impact on whether your diet includes enough of the essential nutrients you need to remain healthy and happy.

It's vital that we get all those nutrients, the carbohydrates, the proteins, the fats, the vitamins, the minerals in that you need to maintain a healthy lifestyle and be happy and healthy.

And so we must make sure that we try to stay within energy balance to make sure we're getting all the nutrients that we need.

So having an occasional calorie deficit won't have much impact.

Probably remember, we said the same, didn't we, with calorie surplus? If it just happens like once in a while, it's not gonna have a huge impact on your body.

However, if you are regularly and consistently in a calorie deficit, your body weight will decrease.

You might begin to feel tired or lethargic 'cause you haven't got enough energy.

That might lead to you being susceptible to illness.

So your immune system might suffer from the fact that you're not getting enough nutrients in your body, and you might start to suffer more illness.

And your cognitive function may suffer.

You might not be able to think as well because the brain needs nutrition too.

And so if we're not fueling the body properly, we may then lead to cognitive function.

You might be a little confused or struggle with doing cognitive tasks.

Okay, now, that's not to say that people should never have a calorie deficit or never have a calorie surplus because actually if you manage it that you have just a slight calorie deficit or a slight calorie surplus, that can be used to improve health and fitness.

For example, somebody who wants to increase muscle mass will require a slight calorie surplus each day.

You need to have a bit of extra calories for your body to put on weight.

And so if you're trying to increase the muscle mass in your body, you will need a slight calorie surplus, otherwise your body won't grow to be bigger.

On the other end of the scale, literally here, somebody who wants to decrease their body weight will require a slight calorie deficit each day.

But I do mean slight and just slightly chip away every day with a calorie deficit to slightly bring down the weight in a healthy manner and not a crash diet where you just cut out all carbohydrates or all fats so that you have much less calories and you very quickly try to lose weight.

That's not a healthy way to do it.

Is this true or false: if you want to lose weight, you should stop consuming calories altogether? Yeah, hopefully you recognise that's false.

And why is that? Well, this would result in you losing weight.

However, it would also lead to many health problems. If you don't consume your BMR, for example, the calories your vital organs need to remain functioning healthily, you'll quickly become tired and susceptible to illness.

A much better method is to gradually and consistently introduce a small calorie surplus every day through physical activity and a balanced diet.

We don't want to try and do too much too soon when it comes to trying to lose weight or put on weight.

We're back with Jacob again.

Now, we know that on Monday, Jacob's very active day, he expended 2,900 calories.

And what I'd like you to do for this task is to calculate how many calories he consumed that day and whether it was a surplus, a deficit, or whether it was balanced.

We're gonna show you the calories in a minute.

Don't worry.

Write a sentence about how Jacob might feel in the short term, based on what you've just discovered.

And then write a passage explaining the consequences, should Jacob consistently achieve this energy balance in his days.

So here is Jacob's calorie consumption.

This is what he ate or drank for breakfast.

He consumed 450 calories.

He had a snack which was 200 calories.

His lunch was 550 calories.

His snack, again, in the afternoon was 250 calories.

And his dinner was 700 calories.

So that will help you now with part one especially.

Okay, pause the video here and work your way through those three tasks, and then rejoin me for some answers.

Right, so Jacob's calorie consumption is what we need to know first, isn't it, before we can do anything else? And the total was 2,150 calories, meaning he was in a calorie deficit of 750.

Okay? Because he'd had a really busy day, hadn't he? As a result of that, Jacob might feel a bit tired and lethargic the next day.

He might struggle to concentrate at school.

So his cognitive function might not be quite as he would hope.

So if Jacob is consistently in a minus 750 calorie balance, the consequences would not be good for his health.

He would lose weight quickly, and he would always be tired, lethargic, and unable to function well, cognitively.

We know he plays basketball, don't we? But he would lack the energy to go to his basketball practise or do any other sports or his PE lesson.

Jacob could find himself getting ill regularly, as his immune system would be weakened.

So being in such a calorie deficit every day is going to be bad news for Jacob.

Just one day is not such a big deal.

Okay? But hopefully the next day he gets into an energy balance again.

That brings us to the end of today's lesson.

Let's read through our summary together.

So we expend energy which are measured in calories or shortened to Kcal, throughout the day, even when we're at rest.

The body requires a minimum amount of calories per day to function, and that's known as their basal metabolic rate.

All activity also expends energy with sports and exercise expending lots of energy depending on the duration and intensity.

Now, a person's age, their gender, their height and their weight also impacts their BMR, and energy expenditure.

Finally, we provide our body with energy by consuming food and drink.

The balance of calories expended and calories consumed can have major implications for our health and wellbeing.

Okay, so I hope that was a useful lesson for you to have a good introduction to energy use, and energy consumption, and energy expenditure.

I'd say the next step there is to learn how exactly a balanced diet should look in terms of the nutrient that you need to make sure that you are getting a healthy, balanced diet.

As I said at the start, this is really useful information for everybody.

We all consume food.

We all expend energy.

We all have a BMR. And so this is not something specific to sports people or those people who are physically active.

In fact, everybody could benefit from knowing a little bit about this.

So share this information with people who you feel might benefit.

I'll look forward to seeing you in another lesson soon.

Bye-bye.