Obesity

Question 1

Describe the energy balance.

Answer 1

There is a balance between energy input and energy expenditure. Obese and overweight people have net energy input.

Question 2

What makes up the majority of energy expenditure?

Answer 2

REE - resting energy expenditure - AKA basal metabolic rate

Question 3

How does REE change with weight loss?

Answer 3

As you lose weight, REE decreases so it becomes more and more difficult to lose more weight

Question 4

How can obesity be defined?

Answer 4

Based on weight

BMI (weight/height^2) - this varies depending on ethnicity

Question 5

What is another measure of obesity that can be used to determine risk of metabolic syndrome?

Answer 5

Waist: hip circumference

A high value indicates increased risk of metabolic syndrome

Question 6

What are the five components of metabolic syndrome?

Answer 6

Waist: hip circumference
Hypertension
Fasting blood glucose
Microalbumin + insulin resistance
Low HDL

Question 7

What waist circumferences give a major risk of CHD in men and women?

Answer 7

Men - >102

Women - >88

Question 8

What polymorphism is associated with increased risk of obesity?

Answer 8

FTO

Question 9

Describe the effect of leptin on regulating energy intake.

Answer 9

Leptin is produced in the adipocytes and communicates with the hypothalamus and lets it know how much fat is stored in the adipocytes thus controlling feeding.

Question 10

Describe the effect of insulin on adipocytes.

Answer 10

Promotes the storage of fatty acids in the adipocytes.

Question 11

What is Ghrelin?

Answer 11

Hunger hormone - when you’re hungry, the Ghrelin levels increase and tell the hypothalamus that you need to eat
Energy expenditure and satiety will DECREASE

Question 12

What is PYY?

Answer 12

Fullness hormone - this is released after a big meal

Question 13

State some complications of obesity.

Answer 13

Hypertension
T2DM
Osteoarthritis 
Cancer
Cardiovascular disease 
CIRRHOSIS

Question 14

What is the only licenced obesity medication in the UK?

Answer 14

Orlistat

Question 15

How does orlistat affect diabetes risk?

Answer 15

It decreases diabetes risk

Question 16

What new medications have been put forward for obesity?

Answer 16

GLP-1 supplements (iraglutide and saxenda)
Belviq - serotonin agonist
Contrave - suppress appetite

Question 17

State the three forms of bariatric surgery.

Answer 17

The stomach is made into the size of a thumb and the second part of the small intestine is joined to the top of the stomach.
The first part of the duodenum no longer sees food and only sees bile.
Food enters the second part of the small intestine much faster than usual.
Vagal nerves are cut by the surgeon so there are changes in perception of food and appetite regulation.

Question 18

Describe gastric bypass.

Answer 18

The stomach is made into the size of a thumb and the second part of the small intestine is joined to the top of the stomach.
The first part of the duodenum no longer sees food and only sees bile.
Food enters the second part of the small intestine much faster than usual.
Vagal nerves are cut by the surgeon so there are changes in perception of food and appetite regulation.

Question 19

What effect does bariatric surgery have on glycaemic control? What are possible mechanisms for this effect?

Answer 19

Bariatric surgery improves glycaemic control
Could be due to decrease in insulin resistance, changes in insulin secretion, changes in gut microbiota, changes in bile salt secretion

Question 20

What are the criteria for bariatric surgery?

Answer 20

BMI 30-35 with short spell of T2DM
BMI 35-40 with comorbidities
BMI > 40 with no comorbidities

Question 21

State another surgical technique used to treat obesity.

Answer 21

Duodeno-jejunal sleeve

Question 22

What are the benefits of bariatric surgery?

Answer 22

Decreased risk of cardiovascular disease
Decreased risk of T2DM
Improvement in hypertension
Reduced cancer related deaths