Obesity

Question 1

What is obesity defined as?

Answer 1

Abnormal/excessive fat accumulation sufficient to adversely affect health and reduce life expectancy

Question 2

What BMI indicates obesity and morbidly obesity?

Answer 2

Obese >30

Morbidly obese >40

Question 3

What is the limitation of BMI?

Answer 3

Body builders/people with a lot of muscle mass have a large BMI but are not obese
Have a thin waist so use waist circumference instead

Question 4

What is the obesogenic environment?

Answer 4

• increased food intake: appetising, cheap, available, high energy density, socio-economic dependent access to healthy diet, food industry more interested in profit than public health
• less exercise: sedentary life style

Question 5

What medications are related to weight issues?

Answer 5

Mood stabilisers
diabetes medicines
corticosteroids
beta blocker
allergy relivers
drugs for migraines/seizures

Question 6

What is the effect of insulin on weight?

Answer 6

insulin makes you fat
- inhibits breakdown and release from fat cells:
decreases lipolysis rate in adipose tissue
stimulates FA and TG synthesis
increases uptake of TG from blood into adipose tissue
decreases rate of FA oxidation in muscle and liver
lipohypertrophy: enlargement of fat cells local to where insulin is injected

Question 7

What is syndromic monogenic obesity?

Answer 7

Exceptionally rare
Mental retardation, dysmorphic features, organ specific abnormalities, obesity
Prader-Willi, Fragile X are examples
1 mutation of 1 gene affecting a wide range of body functions/processes

Question 8

What is Bardet-Biedl & Alstrom syndrome?

Answer 8

Ciliopathy
2 strong links to obesity:
- primary cilium has key role in differentiation of adipocytes -> defect in adipogenesis
- cilia mediate leptin receptor signalling

Question 9

What is non-syndromic monogenic obesity?

Answer 9

1 mutation in any 1 of 12 genes

genes part of leptin-melanocortin pathway

Question 10

How do adipocytes differentiate?

Answer 10

• ciliopathies (primary cilia dysfunction)

- mutations in PPARgamma2

Question 11

What is PPARgamma2

Answer 11

Transcription factor that has a key role in adipocyte differentiation, targeted by TZD drugs

Question 12

How is obesity a heritable trait?

Answer 12

• monogenic obesity
• polygenic obesity (227 genetic variants)
• epigenetic variation

Question 13

What is the difference between apple shape and pear shaped individuals?

Answer 13

Apple shape = more visceral fat = higher risk of weight related health problem

Pear shape = less visceral fat = lower risk of weight related health problem

Question 14

How can obesity lead to type 2 diabetes?

Answer 14

• chronic inflammation
• altered adipokine levels as high leptin levels
• breakdown of fat metabolism (lipid accumulation in tissue)
• breakdown of glucose metabolism regulation

Question 15

What drugs treatments are there for obesity?

Answer 15

Orlistat - reduces amount of fat absorbed from food eaten by acting as a lipase inhibitor

Question 16

What surgery can be done for obesity?

Answer 16

• weight management course first so taught about diet/nutrition/fitness/exercise
• laproscopically after conventional treatments failed
• if morbidly obese or BMI>35 and have obesity related complications
• restrictive procedures: restrict food passage with gastric banding/vertical banded gastroplasty and sleeve gastroplasty
• malabsorptive procedures: reduce ability to absorb nutrients
• restrictive plus malabsoprtive procedures (duodenal switch, Roux-en Y gastric bypass, intragastric balloon)

Question 17

What are the main malabsoprtive surgical procedures for obesity?

Answer 17

Biliopancreatic diversion
Roux-en-Y gastric bypass

Can cause nutrient deficiencies, malnutrition, anastomotic leaks, dumping syndrome (rapid gastric emptying)