Lesson video

Hi there, I'm Mrs. Kemp and welcome to today's lesson.

It's titled "Imbalanced Diet: Obesity" and it's from the unit "Diet and Exercise.

" Some of the information will be completely brand new to you, but actually you might know some of this from back in primary school when you looked at healthy diets.

Okay, so let's have a look at what our outcome is for today.

I can explain the effects on the human body of consuming too much food.

We have these keywords that we will be using today and I'm not gonna read them out to you now, but if you want to pause the video, then you can.

We have three learning cycles for today.

We have "Consuming Too Much Food," "BMI," and "Effects of Obesity on the Body.

" We are gonna start with "Consuming Too Much Food.

" Let's have a look at these sumo wrestlers to start off with.

This is a sport that actually originated in Japan.

It's really, really popular in Japan.

How do you think those sumo wrestlers actually get to that size 'cause they are rather large?

So they actually eat 20,000 calories each day.

That's about 10 times the recommended daily amount for an adult.

Their life expectancy is a lot lower than the average person in Japan.

It's actually 10 years lower and that's because of the size that they are at for most of their lives.

However, because the prestige of competing as a sumo wrestler is so important in Japan, actually many families believe that it's worth it and that's why they still continue to carry on with the sport.

So when choosing our food, it is really important that we consider the amount of energy that is in that food.

We need to make sure that there is a really good balance of the amount of energy that we are taking into our bodies and then the amount of energy that we're actually using.

Think about those scales there in the picture.

We want to try to balance those two: energy input and energy output.

We do use a lot of energy all the time.

We use it for movement and growth, but in fact we even use it when we are sleeping.

Our cells still need to have all of those chemical reactions happening, even if it is at a slower rate when we're sleeping.

Modern diets are unfortunately very high in calories or often very high in calories and actually low in nutritional value.

So they don't have all those wonderful vitamins and minerals of normal food.

Ultra-processed foods, they are often very high in saturated fat, or very high in sugar, or sometimes both.

This can imbalance the amount of energy that is going in to actually what is coming out.

And these types of foods are not only linked to people putting on weight, they're also linked to certain types of diseases such as cancer.

So we should think very, very carefully when choosing this as our food and try to reduce it as much as possible.

Often they are very cheap and very accessible, which is why we find, in lots of societies, these types of foods increasing in people's diets.

Okay, onto our first check of today, which factors can affect the amount of energy a person needs?

a, activity levels b, age, or c, nationality.

Have a little think about it for a moment, but if you need more time, please do pause the video.

Okay, we've got activity levels, did you choose that one?

And also age.

Both of these things will affect the amount of energy a person needs.

The nationality isn't going to have much of a difference.

Onto our first practice of today.

Task A, you would like to get out your worksheet so that you can record your answers on there for me.

So answer the questions: number one, suggest why a sedentary teenager needs more energy per day than a sedentary person in their 40s.

Remember, sedentary means that they don't move around a great deal.

Number two, a man in his 40s changes from being very active to sedentary.

He continues to eat the same food, or same amount of food each day, how might his body change?

Number three, which types of food and drinks should we reduce or avoid in our diets to maintain a healthy weight and why?

Okay, I'll give you a little moment to think about it, but if you do need more time, please do pause the video.

Okay, did you think of all of these.

For number one, the teenager is growing and this requires extra energy, but a person in their 40s is no longer growing.

Number two, he might gain body fat and could become obese as he no longer needs to use some of the food as a source of energy, so it will then be converted into fat.

Number three, we should try to avoid highly processed foods and drinks.

You might have given an example of that instead of saying highly processed, like pizzas and crisps.

They tend to be high in fat and sugar, which can lead to an imbalance in the amount of energy we consume and what we need.

Excellent, well done.

Onto our second learning cycle of today, then, this one is entitled "BMI.

" So one way that we can tell if a person has been eating too much is to calculate their body mass index or BMI.

This is the calculation that we need to use for body mass index.

We have used it previously in the "Imbalance Diet: Starvation and Deficiency Diseases.

" If you would like to record it, it might help you for later on.

Body mass index then is equal to body mass divided by the height squared.

Remember that we really need to be careful with the types of units that we are using in order for this calculation to be correct.

So kilograms per meter squared is our body mass index.

The body mass needs to be in kilograms and the height needs to be in meters, so we must convert any units that are not in kilograms or meters for our calculation.

The BMI, then, is then used to find out if a person is a healthy weight and these are the categories that are for adults, okay?

They are not used when we are talking about children.

If the BMI is less than 18.

5, they're underweight.

If it's between 18.

5 and 24.

9, they are a healthy weight.

Anyone between 25 and 29.

9 would be overweight.

Between 30 and 39.

9, they would be obese, and 40 or more will be severely obese.

There are actually some limitations to this BMI calculation and sometimes people can end up being in a different category to actually what is really representative of that person's body fat.

For example, a professional sports person, they've actually got a really high level of muscle tissue in their bodies and muscle tissue does weigh a lot when that person gets on the scales.

So they end up having a slightly skewed BMI, and actually what they end up with is saying that they are overweight or potentially even obese when in fact they don't have a great deal of fat in their body.

There are some other options to the BMI.

This one tends to be really popular with kind of nutritional scientists, so the people that are really looking into nutrition and health, and this is the waste-to-height ratio.

The reason that we're really interested in this one is because actually we store a lot of fat around our middles and this is when it's really associated with quite high risk of developing certain diseases later on.

We'll talk about that in our final learning cycle.

So what they do here is that they will measure a person's weight and height and you have to measure that in the same unit.

So it could be that they're both in centimeters, it could be that they're both in meters.

Divide that waist measurement by the height measurement.

A ratio of 0.

5 or higher means a person has an increased risk of health effects associated with obesity, okay?

We will be discussing what those health effects are in our later learning cycle.

There is another one, and for this you need an instrument, you need something called a caliper.

Calipers are super cheap.

So lots of people do use this.

Often they'll use this in gyms.

And what they do here is they pull a fold of the skin away from the body and they use the calipers to measure the thickness of that fold of skin.

They need to do this in at least three different areas.

They might do your tummy, they might do your thighs, they might do your underarm, okay?

The measurements are then inputted into an online skinfold measurement calculator, so you need to be online for this, to work out a person's body fat percentage, okay?

And then you can tell whether or not that person is healthy.

So these are two other options that we could use for BMI.

Okay, so let us have a go at calculating BMI.

A 43-year-old woman is 154 centimeters and has a mass of 83 kilograms.

Calculate her BMI.

We will need to use the fact that 100 centimeters is 1 meter because remember, what we need to do first is we need to convert our centimeters into meters.

To do that, we take the 154 centimeters, that is her height, and we divide that by 100 and that gives us 1.

54 meters.

We can then square her height in meters and 1.

54 squared is equal to 2.

3761 meters squared.

If we then put that into our equation to calculate BMI, we get 83 divided by 2.

3761 and that will be equal to 34.

9 kilogram per meter squared.

We then use our table from earlier that told us the categories and that tells us that this lady is obese.

Okay, I'd like you to have a go at this one for yourself.

So a 24-year-old woman is 161 centimeters and has a mass of 103 kilograms.

Calculate her BMI.

Remember that 100 centimeters is equal to 1 meter.

I'll give you a little bit of time to think about it, but if you need more time, please do pause the video.

Okay, so first of all, we needed to convert our centimeters into meters and that gives 161 divided by 100 which gives us 1.

61 meters.

We can then square her height in meters and that is 1.

61 squared, and that gives us 2.

5921 meters squared.

If we put that into our equation for BMI, then, we get 103 divided by 2.

5921, which gives us a number of 39.

7.

If you look that up in the table from earlier, we can see that that person is severely obese.

Okay, let's have a practice at using this table.

Can you use the table to decide which person is a healthy weight?

Is it the person with the BMI of 42.

3, b, the BMI of 23.

5, or c, the BMI of 25.

6?

I'll give you a moment to think about it, but if you do need more time, please pause the video.

Of course, it's b, the person with the BMI of 23.

5.

I hope you got that right.

Well done.

Let's go on our second task of today, task B.

Again, you can find this on your worksheet so please do get it out so you can record your answer.

Rishi is a 25-year-old professional athlete who has recently had a full medical.

He was told his BMI is 31.

5 and therefore, he's classed as obese.

What advice would you give to Rishi?

Consider whether his BMI is too high and other checks he could have carried out by professionals.

I'll give you a moment to think about it, but if you need more time, please do pause the video.

Okay, let's have a little look at what kind of advice we could have given Rishi then.

So Rishi is a professional athlete and therefore, his muscle mass may be affecting his BMI.

Before changing his diet, Rishi should have his body fat measured in a different way by a professional.

For example, his waist-or-height ratio or his skinfold measurements.

If either of these tests still report that he has excess body fat, then he should try to reduce his energy intake in his food and eat a more balanced diet.

You may have suggested things that he might want to reduce in his diet, such as ultra-processed foods, in order to make sure that we are balancing that amount of energy.

So onto our final learning cycle of today: "Effects of Obesity on the Body.

" So obesity can have many adverse effects, adverse means sort of dangerous, on our physical and mental health.

The following are all health conditions linked with obesity.

One thing is type 2 diabetes, we've got coronary heart disease, some types of cancer, stroke, depression.

Let's have a little think about one of those in more detail.

Type two diabetes, it's actually a disease whereby the patients are unable to control their blood sugar levels.

Symptoms can include things like frequent urination, so needing to go to the toilet a lot more than you do normally, but also having excessive thirst, so feeling thirsty all the time and needing to drink.

When you cut yourself, actually it takes a really long time to heal, much longer than it would do normally.

This can be really dangerous for people with type two diabetes because it can mean that they are very prone to infections from that point.

If left untreated, then, so if you don't go to the doctor and you don't get some help prescribed to you, it can actually lead to more serious problems with things with your eyes, with your heart, and also with your nerves, as part of your nervous system.

The heart then is a muscle.

Remember, it's made up of that special type of muscle called cardiac muscle, that is made up of muscle cells.

The muscle cells require a really good supply of energy in order to work.

Now actually, the heart itself gets a supply of the fuel that is needed for that energy from the coronary arteries.

And we can see that that heart there is labeled to show where those coronary arteries are, they're surrounding the surface of the heart and they bring the blood to the heart muscle.

What they're carrying in the heart, then, is that fuel of oxygen and glucose and this is needed for cellular respiration to provide energy for that heart muscle to contract.

Remember, the heart muscle contracts and requires energy, and relaxes, it doesn't require energy.

Coronary heart disease, then, which is also linked with obesity, happens when the coronary arteries that supply the heart with blood get blocked.

You can see there in the image that what's happened inside that artery is we've got a buildup of some fatty tissue.

This is going to reduce the blood flow.

We can see that there are lots of red blood cells flowing into that coronary artery and not as many getting past as it gets to that fatty buildup.

If the coronary arteries are blocked, then, like in that image, this can lead to a heart attack.

You've probably heard of heart attacks and how serious they can be.

If the blood supply to the heart is stopped, then the heart muscles can no longer receive the reactants that are needed for cellular respirations, so they're no longer going to get the oxygen and glucose that are required.

This can result in those heart muscles no longer contracting and actually dying.

If a large enough proportion of the heart becomes damaged, so a good deal of those heart muscle cells actually have died, it can cause cardiac arrest and potentially death.

Which of the following, then, can people suffer from as a result of obesity?

a, coronary heart disease, b, depression, c, high muscle mass, or d, low BMI.

I'll give you a moment to think about it, but if you need more time, please do pause the video.

Okay, did you think of both of coronary heart disease and depression?

You are right.

Excellent.

Well done.

Let's go on to our final task of today then, okay?

So please get your worksheet back out, you can record your answers on there.

Number one, you need to draw and label a diagram to show the effect of a fatty substance building up in an artery.

And number two, explain how a blocked artery may lead to a heart attack.

I'll give you a moment to think about it, but if you need more time, please do pause the video.

Okay, your picture should look something like this then.

We've got our artery and we can see that we've got our red blood cells going into our artery, but unfortunately, number two there, we've got a fatty buildup blocking that artery and so number three, as a result of that we can see that there is a narrower space for the blood to pass, and then number four, you can see that there's not actually enough blood getting through.

So there's many less cells coming out than there is going in.

Our answer to number two, then, to explain how a blocked artery may lead to a heart attack.

First point, the coronary arteries supply the heart with blood.

It's important to mention that.

The blood brings oxygen and glucose to the muscle cells in the heart for cellular respiration.

Remember that that is the fuel that is needed.

If the arteries are blocked, then not enough blood flows through them, this leads to a heart attack.

I hope you got all those points there, but if you didn't, please do add a couple of extra onto the bottom of your worksheet.

Well done.

So it's been great today and I've really enjoyed this lesson, but we have come to end.

Let's just go through some of those summary points then.

So the key learning points for today.

Not consuming a balanced diet can lead to ill health.

We need to balance the amount of energy we are taking in with the amount of energy we are using.

Body mass index or BMI is calculated from a person's height and body mass.

Consuming too much food can cause your BMI to become high and lead to obesity.

Obesity can increase the risk of developing health issues including type 2 diabetes and coronary heart disease.

Thank you so much for watching today and I hope to see you again soon.

Thank you very much.

Bye now.