OBESITY

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.

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.

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

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.

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

INCIDENCE OF OBESITY

A significant proportion of the Australian population is classified as overweight or obese

PHYSICAL EFFECTS OF OBESITY

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.

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.

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?