1. Obesity

2. Obesity
Obesity occurs when the energy intake is greater than the energy expenditure through physical activity; the excess energy is stored in the body as adipose tissue.
A body weighing 10 to 19 per cent above the ideal weight is classified as overweight.
A body weighing 20 per cent or more above the ideal weight is classified as obese.
Obesity has both short-term and long-term health consequences that become more severe as the condition worsens.

3. Causes of Obesity
Obesity is not caused just by eating too much and inactivity. Other factors determine whether excess energy intake will lead to excess adipose tissue.

4. Assessment of obesity
Waist circumference and waist-to-hip ratio. These methods look only at someone's body shape and do not assess overall body fatness. Fat around the middle of the body, where the organs are, is called central obesity and is associated with a higher risk of health problems. Waist circumference can be measured and compared with standard values; in both children and adults, a large waist circumference indicates central obesity. Waist-to-hip ratio is used mainly to assess body shape in adults. The ratio is calculated as follows:
An ideal waist-to-hip ratio is about 0.7 for women and 0.9 for men

5. Assessment of obesity
Skinfold tests. Special calipers are used by professionals to measure the thickness of skin folds at particular sites on the body; these measurements are then compared with tables of normal values. This makes it possible to estimate how much of a person's weight is adipose tissue. In men, adipose tissue is normally around 15 to 20 per cent of their total body weight; in women, it is about 20 to 25 per cent of body weight.

6. Assessment of obesity
Body mass index (BMI). The BMI is calculated as follows:
CLASSIFICATION
BMI
Severely underweight
<17.9
Underweight
18–19.9
Acceptable weight
20–24.9
Overweight (grade I obesity)
25–29.9
Obese (grade II obesity)
30–34.9
Morbidly obese (grade III obesity)
40 or more

7. Incidence of obesity
A significant proportion of the Australian population is classified as overweight or obese

8. Physical effects of obesity

9. Physical effects of obesity
Obesity can cause significant health problems because of:
the extra workload for the heart in pumping blood around a larger body
considerable strain on the body's joints, particularly the knees, hips and ankles
the reduced effectiveness of the body's temperature control mechanisms
fatigue from simple physical tasks, because the body requires more energy to move.

10. Physical effects of obesity
Obesity also increases the risk of the following conditions:
diabetes mellitus
gall bladder disease
cardiovascular disease
hypertension, leading to stroke
hiatus hernia
respiratory disorders
musculoskeletal disorders (such as arthritis)
some cancers.
Many of these conditions can cause premature death.

11. Activity
Harold is 18 years old. He is 179 centimetres tall and weighs 80 kilograms. He has gained weight over the past three months after breaking his leg while playing football. His normal weight was 67 kilograms before his accident, when he was much more active with football games and regular training. He has noticed that his leg muscles have decreased in size since he stopped training, and his abdomen is larger. His waist circumference is now 85 centimetres and his hip circumference is 83 centimetres.
Calculate Harold's BMI, using his current weight and also his weight before the accident.
What weight range is ‘acceptable’ for Harold?
What would Harold's weight be if he was classified as ‘severely underweight’?
What would Harold's weight be if he was classified as ‘grade III obese’?
Work out Harold's waist-to-hip ratio. What does this indicate about Harold's weight gain?