Lecture 19

Question 1

What is obesity?

Answer 1

When enrrgy intake exceeds energy expenditure
An abnormally high proportion of fat
A serious chronic disease
Multi-factorial disease
A disease which affects all ages, and socio-economic groups

Question 2

What is energy homeostasis?

Answer 2

Energy Balance which aims to maintain a relatively stable body weight

Question 3

What makes up energy intake?

Answer 3

Food consisting of protein, fat and carbohydrates

Question 4

What makes up energy expenditure?

Answer 4

Physical Activity
Basal Metabolic Rate
Diet induced thermogenesis?

Question 5

What is diet induced thermogenesis?

Answer 5

As soon as food consumption begins temperature increased as an attempt to burn off excess calories

Question 6

How is obesity measured?

Answer 6

Anthropometric measurements including height, weight, circumference and diameters, skinfold thickness
Isotope or chemical dilution
Body Density or Body Volume (Where the person is immeresd in water to measure volume displacement)
Imaging techniques such as MRI`

Question 7

What is BMI?

Answer 7

Body Mass Index, determined by weight in kg divided by height in meters squared

Question 8

What are the flaws with BMI?

Answer 8

It doesn’t take into account facts like gender, ethnicity or age and doesn’t take into account where the body fat is being stored

Question 9

How does where fat is stored play a role in obesity?

Answer 9

Subcutaneous fat is regarded as being good while waist and abdominal fat is regarded as being the bad damaging fat

Question 10

What are the parameters for BMI?

Answer 10

18.5-24.9= Healthy weight
25-25.9= Overweight
>30= Obesity

Question 11

What are more accurate measures of obesity than BMI but is still based of anthropometric measurements?

Answer 11

Waist circumference is used as a measure of abdominal fat risk of developing obesity is when >88cm for women or >102cm for men
Waist to hip ratio is calculated by dividing waist circumference by hip circumference risk of obesity occurs at >0.9 for men and >0.8 for women

Question 12

What are the causes of obesity?

Answer 12

Genetic component
Environmental factors
Psychological factors
Fetal Programming

Question 13

What are the potential consequences of obesity?

Answer 13

Type 2 Diabetes
Cardiovascular disease and hyper tension
Increased risks of cancer
Sleep apnoea
Gall bladder disease/gall stones
Oesteoarthritis (due to increased strain on hip and knees)
Reproductive problems
Emotional Problems

Question 14

What are the features of the worldwide obesity epidemic?

Answer 14

Obesity has increased by 1/3 in the last decade
Incidence rates are higher in Maori populations
Also occurs in children and adolescents

Question 15

What is likely to be the cause of the new worldwide obesity epidemic?

Answer 15

Genetic factors can not have changed this rapidly therefore the change is most likely to be predominantly to be dues to changes in the environment

Question 16

What are the molecular mechanisms which regulate body weight?

Answer 16

Hormones (such as leptin) and neuropeptides, these mechanisms can be highly variable among individuals

Question 17

How does leptin regulate body weight?

Answer 17

Leptin is produced by adipose tissue, an increase in leptin concentraion leads to a decrease in AP Peptide and a decrease in body weight

Question 18

Why does giving leptin to humans not always work?

Answer 18

Often there are already high levels of leptin in obese people as they have large amounts of adipose tissue, but it is ineffective as they have developed leptin resistance

Question 19

What are the key areas of the brain which control obesity in humans?

Answer 19

Hypothalamus and the brainstem which recieve hormones from both adipose tissue and the gut

Question 20

What are the short term regulators of diet?

Answer 20

Ghrelin (Hunger hormone)
CCK
PYY3-36

Question 21

What are the key neurons in in regulating obesity/diet?

Answer 21

NPY and POMC neurons

Question 22

What are some of the common mutations result in obesity?

Answer 22

Mutation in the leptin/insulin transporter
Mutation in the POMC neuron
Mutation in the MC4R neuron

Question 23

What are the results of the mutation in the POMC gene?

Answer 23

Recessive pattern of inheritence
red hair
hyperphagia
obesity

Question 24

How is obesity treated?

Answer 24

No safe, effective drugs exist
The best method is high cost, high risk surgery
Most of the focus is on prevention including things like diet, exercise, and behavior modification