1. Weight Problems Topic 9.7 Animal Systems

2. We have looked at how different people have different energy requirements. But what happens if a person takes in more food than they need???? In today’s lesson we will investigate how having too much or too little food can affect a person’s health.

3. If you take in too much food (energy) then your body will store what it doesn’t need as fat. If you continue to take in extra food over a long period of time you will put on weight and you may become obese.

4. What does “obese” mean? To work out whether someone is obese or not we have to first take two factors into account: Height and weight Using this information we can work out a persons body mass index (BMI)

5. BMI To calculate a persons BMI we use the following formula BMI = Weight (Height) 2

6. For example Caroline has a mass of 48 kilograms, her height is 1.5 metres. Caroline’s BMI = 48 = 48 =21.3 (1.5) 2 2.25

7. Once we know a persons BMI we can assess whether they are healthy or not. A BMI value below 18.5 means the person is under weight. Above 35 the person is obese. Being Obese can cause lots of health problems

8. How can we lose weight? Reduce the amount of energy (food) you take in. Increase the amount of energy you use by doing more exercise. Most people do a combination of the two.

9. Starvation In some parts of the world people do not have enough to eat. This leads to starvation. People that are undernourished can become very thin as their muscles waste away. They also become more susceptible to disease.

10. Diet advise Choose Homer or Mr Burns and write down some diet advice for them.