L11 Physiology of appetite and weight

Question 1

What methods can be used to measure weight?

Answer 1

BMI
Waist circumference
Skin-fold thickness
Bioelectrical impedance analysis
Ethnicity specific cut-offs

Question 2

What are the BMI measurements?

Answer 2

<18.5 - underweight
18.5 - 24.9 - overweight
30-39.9 - obese
≥40 - morbidly obese

Question 3

What is the definition of obesity?

Answer 3

A BMI above 30 kg/m2

Question 4

What are some consequences of obesity?

Answer 4

Metabolic syndrome
Type II diabetes
Cardiovascular disease
Respiratory disease
Liver disease
Cancer
Reproductive dysfunction 
Joint problems
Psychological morbidity

Question 5

What is metabolic syndrome?

Answer 5

Cluster of closely - associated cardiovascular risk factors

Question 6

What is metabolic syndrome associated with?

Answer 6

BMI > 30
Visceral obesity
Dyslipidaemia
Hyperglycaemia
Hypertension

Question 7

What is the underlying pathophysiology of metabolic syndrome?

Answer 7

Insulin resistance

Increased free fatty acids
Pro-inflammatory cytokines

Question 8

What are the risk factors for type II diabetes mellitus?

Answer 8

Age
Obesity
Family history
Ethnicity

Question 9

Why is the prevalence of type II diabetes mellitus increasing?

Answer 9

Ageing population
Increasing obesity which is becoming more common in younger population
Increased detection / diagnosis
Increased survival

Question 10

Describe cardiovascular disease

Answer 10

Metabolic syndrome plus:

• Increased blood volume & blood viscosity
• Increased vascular resistance
• Increased hypertension
• Increased left ventricular hypertrophy
• Increased coronary artery disease
• Increased stroke

Question 11

Describe respiratory disease

Answer 11

Obstructive sleep apnoea
Hypoxia / hypercapnia
Pulmonary hypertension

Question 12

Describe GI / liver disease

Answer 12

Non-alcoholic fatty liver
Non-alcoholic steatohepatitis
Gallstones
Reflux

Question 13

What can non-alcoholic fatty liver and steatohepatitis progress to?

Answer 13

Cirrhosis
Portal hypertension
Hepatocellular cancer

Question 14

What types of cancers can be caused by obesity?

Answer 14

Breast
Endometrial
Oesophagus
Colon
Gallbladder
Renal
Thyroid

Question 15

What are the mechanisms of cancer associated with obesity?

Answer 15

Increased insulin
Increased free IGF-1
Increased oestrogen
Adipo-cytokines
Reflux

Question 16

What are the symptoms of PCOS?

Answer 16

Oligomenorrhoea
Hirsutism
Acne

Question 17

What are the consequences associated with PCOS?

Answer 17

Subfertility
Endometrial hyperplasia
Insulin resistance

Question 18

What are some of the effects of obesity on the reproductive system?

Answer 18

PCOS
Male hypogonadism
Adverse pregnancy outcomes

Question 19

What is the effect of obesity on joints?

Answer 19

Osteoarthritis

Gout

Question 20

What are the psychological effects of obesity?

Answer 20

Depression

Eating disorders

Question 21

Describe the genetic causes of obesity

Answer 21

Rare: obesity-associated syndromes such as Prader-Willi and Bardet-Biedl

Common: polygenic, susceptibility genes, heritability of weight

Question 22

Describe the environmental causes of obesity

Answer 22

Diet: high fat, low sugar, socioeconomic factors

Physical activity: 20-50% of total energy expenditure, socioeconomic factors

Question 23

Describe the relevance of the gut microbiome in obesity

Answer 23

Differences in gut bacteria between those with obesity / type II DM and health individuals
Transplantation of faecal matter alters insulin sensitivity

Question 24

Describe the role of leptins in obesity in the human

Answer 24

A leptin deficiency or mutation of the leptin receptor can cause obesity

Increased leptin concentration is associated with increased fat
Possibly leptin resistant
Possible decrease in CNS transport of leptin

Question 25

What does CCK do?

Answer 25

Induces satiety which inhibits eating

Question 26

What does ghrelin do?

Answer 26

Induces eating

Question 27

What does PYY do?

Answer 27

Inhibits eating for up to 12 hours

Question 28

Describe changes in diet to help lower weight

Answer 28

Diet
500-1000kcal energy deficiency
Low energy density: decreased saturated fat, decreased sugar, increased fruit and veg
Decreased portion sizes
Decreased snacking
Structured meals / meal replacements

Question 29

Describe changes to physical activity to help lower weight

Answer 29

Exercise 7 days a week
- 30 min moderate / high intensity
- 60 min low intensity
10,000 steps per day
Exercise will increase health regardless of weight loss

Question 30

Describe the mechanism of orlistat

Answer 30

Binds and inhibits lipases in lumen of the gut
Prevents hydrolysis of dietary fat into absorbable free fatty acids / glycerol
Excrete 1/3 dietary fat

Question 31

What are the adverse effects of orlistat?

Answer 31

Flatulence, oily faecal leakage, diarrhoea

Decreased absorption of fat-soluble vitamins

Question 32

What is the best 1st line agent for overweight / obese patients with T2DM?

Answer 32

Metformin

Question 33

Describe laparoscopic adjustable banding

Answer 33

Restrictive only

Inject / withdraw saline to adjust diameter of the band

Question 34

Describe roux-en-Y gastric bypass

Answer 34

Restrictive
Malabsorptive
Alterations in gut hormone and bile acid flow which contribute to weight loss

Question 35

What are some consequences that can occur due to roux-en-Y gastric bypass?

Answer 35

Micronutrient deficiencies

Dumping syndrome

Question 36

What are the disadvantages of surgical treatment for obesity?

Answer 36

Perioperative mortality / morbidity
Long-term follow up
Some weight re-gain
Expensive

Question 37

Describe the NICE guidelines for bariatric surgery in 2006

Answer 37

After failure of other options if:
-BMI > 40kg/m2
- BMI > 35 with co-morbid conditions
First line if BMI >50

Question 38

Describe NICE guidelines for bariatric surgery in T2DM

Answer 38

Expedite bariatric surgery if BMI > 35

Consider surgery if BMI > 30

Question 39

Describe the NICE guidelines for bariatric surgery in 2013

Answer 39

Must have been obese for at least 5 years

Must engage with non-surgical weight loss programme for 12-24 months first