13. Obesity

Question 1

What are thrifty genes?

Answer 1

• Genes which enable individuals to efficiently collect and process food
• Deposit fat during periods of food abundance
• Done in order to provide for periods of food shortage

Question 2

Which part of the brain is associated with the satisfaction of the need for food?

Answer 2

• Satiety centre
• Located in the ventromedial nucleus of the hypothalamus
• If damaged - produces uncontrollable hyperphagia and obesity

Question 3

Which part of the brain is associated with hunger?

Answer 3

• Feeding centre
• Located in the lateral hypothalamus
• Stimulation - eat whether hungry or not
• If damaged - hypophagia and weight loss

Question 4

What does Neuropeptide Y stimulate?

Answer 4

• Feeding

• rich in tyrosine

Question 5

What does Glucagon-like peptide stimulate?

Answer 5

• Satiety factor

* Stops eating

Question 6

Where is leptin synthesised and what does it do?

Answer 6

• Synthesised in fat
• Tells hypothalamus how much fat you have
• Inhibits hunger

Question 7

Why does a lack of fat result in less/no periods?

Answer 7

• Fat tissue produces LH

* Lack of fat => lack of LH => lack of periods

Question 8

What metabolic factors can coseggregate to increase the risk of obesity?

Answer 8

• Waist circumference (men > 102, women > 88), if omental fat > peripheral fat
• Type II diabetes
• Hypertension
• HDL count (men < 1.0, women < 1.3)
• Fasting glucose (>6.0mmol)

Question 9

How have dietary patterns changed to increase weight gain?

Answer 9

• Increased fat
• Decreased carbohydrates - important for energy storage and satiety
• Therefore, reduced satiety

Question 10

Which hormone that comes from the ileum and colon is important in the control of satiety?

Answer 10

Peptide YY

Question 11

What are the complications of obesity?

Answer 11

• Increased morbidity and mortality
• Economic & psychological costs
• Increased CVD, GI disease, endocrine, gynaecological & obstetric etc.

Question 12

How can obesity be treated?

Answer 12

• Lifestyle, diet and exercise
• Difference between ideal + actual outcome of weight loss - psychological barrier - failure over long term
• Pharmacological intervention for long term
- Orlistat
- GI lipase inhibitor - reduction of fat absorption
• Gastric bypass - prevents calories coming into contact with duodenum
• Gastric banding - reduces size of stomach - earlier satiety