Topic 4 - Obesity a growing problem

Question 1

Defining obesity

Answer 1

Simplest method in adults = BMI and measuring waist circumference
• Some limitations - but good relationship between these measures and health risk

Question 2

BMI – Body Mass Index

Answer 2

• Measures body mass not fat
• Correlates well with health risk:
BMI > 25 associated with ↑ risk of CHD, diabetes, gall bladder disease, high blood pressure and high cholesterol
BMI: W (in kg)/ H2 in M

Question 3

Classification of obesity

Answer 3

40 kg/m2 = Class 3 severe morbid obesity

NB: different ranges apply for Maori and Asian people

Question 4

Waist circumference

Answer 4

• Measures location of body fat
• Can also use waist : hip ratio
Defining obesity in children
♀>80cm ♂>94cm = Increased Risk
Substantial risk
♀ > 88cm ♂ >102cm

Question 5

Defining obesity in children

Answer 5

• Cannot use BMI in kids - use BMI for age charts
• Overweight = 85th -95th percentile
• Obese = > 95th percentile

Question 6

Children: weight and waist

Answer 6

•5% ‘underweight’
•72% ‘normal weight’ 
•17% ‘overweight’
•6% ‘obese’
Waist:
•On average, 1 in six has a waist girth greater than recommended

Question 7

Factors influencing obesity

Answer 7

* Genetic
Leptin
Thrifty gene
Prenatal effects
* Environment
Total kJ & Fat
Food prefs
Satiety
Alcohol
Exercise
* Behavioural
Education
Culture
Mood
TV watching
Social norms

Question 8

Factors influencing obesity all factors

Answer 8

• Physiology – BMR, muscle, hormones, pregnancy, activity
• Social – Choice, sedentary lifestyle, more eating out, discrimination
• T echnological – Leisure, work, “fat-pill”, functional foods, nutragenomics
• Economic – Large retailers dominate food supply chain, foods for profit,
advertising pushing consumption • Environmental
– Urbanisation, 24 hour access to energy dense foods, all year access to “all foods”, car use
• Political – Threat of litigation in relation to foods, advertising; fat tax; BUT no
proven National success stories • Cultural
– How do we see ourselves? Expectations about food, diet and physical activity are formed, shared and changed.

Question 9

TV and Obesity

Answer 9

• TV viewing more strongly related to obesity than physical activity patterns and diet.
• Less than 2 hours per day recommended.

Question 10

Managing obesity - strategies

Answer 10

Medical: medications, surgery - inhibit, surgery - restrict
Environment: Exercise, ‘diets’ - fad or other, lifestyle change, VLCD
Social: Education, culture change, counselling, portion sizes, food supply change

Question 11

Response of the food industry

Answer 11

• Compliance with food labelling
 – Kilojoules and calories
 – Serving size
- Problems:
- confusing food claims e.g. 97% fat free/low fat
- diet varieties = over consumption?
- What is a serve e.g. yoghurt, MMs

Question 12

What about the food industry ?

Answer 12

• Application of new technologies
 – Low and no fat foods with good mouth feel
 – Sterol margarines
• Greater range of foods 
– 1000 products in 1950s 
– > 15 000 products now
• Positive role models 
– Eg Wiggles promote
healthy food eg weet bix 
– Eg Shrek custard
– Problems: ? Fresh fruit and vegie role models

Question 13

Positives from the food industry

Answer 13

• Light meals/ smaller serves / pre-pack
• Low GI foods and recognition
• Low Na campaign for packaged foods
• Availability of nutrient comp data
• Specialised foods eg low fat / etc
• Fortification eg DHA/ folate etc