SM165/166 Obesity Etiology and Pathophysiology

Question 1

BMI equation

Answer 1

BMI = weight (kg) / height (m) squared

Question 2

BMI categories

Answer 2

30 = obesity
>35 = severe obesity
>40 = morbid obesity
>45 = super obesity

Question 3

Do obese people eat more or less? Do they burn more or less energy?

Answer 3

Eat too many calories, actually burn more due to a higher amount of lean body mass (BMR and cost of physical activity). Overall higher energy flux.

Question 4

Why do obese people have more lean body mass?

Answer 4

Muscle is added as you gain weight to be able to handle the extra load

Question 5

When you gain weight, what is the fat/lean proportion?

Answer 5

2/3 fat mass, 1/3 fat-free mass (lean)

Question 6

What is NEAT? Is it high or low in obese people?

Answer 6

NEAT = non-exercise activity thermogenesis
The energy expended for everything that is not eating, sleeping, or intended exercise
Lower in obese people

Question 7

Changing energy expenditure concept

Answer 7

When you raise your energy balance (amount taken in - amount burned), you initially gain weight. Eventually your balance resets at the higher intake level so that you are burning more energy and you stop losing weight

Question 8

Relationship between caloric intake and physical activity

Answer 8

People with active lifestyles take in a higher amount of energy. People with mildly active lifestyles take in less. Below a certain threshold of activity, energy intake increases a lot (these are the people that are obese a lot)

Question 9

Prader-Willi Syndrome: chromosome, imprinting role (which parent?), clinical signs

Answer 9

15
Paternal allele is not expressed
Obesity, hyperphagia, retardation, hypogonadism

Question 10

Prenatal factors in obesity

Answer 10

Excessive weight gain and poor glycemic control contribute to development of obesity in the child

Increased circulating lipid levels reach the fetus and change gene regulation

Question 11

Do men or women have higher fat levels at the same BMI? Why?

Answer 11

Women - less muscle than men

Question 12

Adipokines

Answer 12

Cytokines secreted by adipose tissue

Examples: IL-6 (leads to hypertryglyceridemia) leptin, TNF-a (macrophage infiltration), adiponectin

Question 13

What kind of fat has important endocrine/metabolic activity in obesity?

Answer 13

Visceral abdominal fat within the omental cavity

Intrahepatic fat is also important

Question 14

Which adipokine goes up in obesity?

Answer 14

Adiponectin - low levels lead to insulin resistance

Question 15

Obese adipose tissue histology

Answer 15

Cells hypertrophy and release factors that recruit macrophages, leading to inflammation

Question 16

Obesity and insulin

Answer 16

Increasing levels of obesity are associated with hyperinsulinemia and insulin resistance

Improves with weight loss

Major risk factor for type II DM

Question 17

Insulin resistance causative factors

Answer 17

1) free fatty acids, 2) ectopic fat, 3) more TNFa and IL-6 and less adiponectin

Question 18

Does liposuction improve outcomes?

Answer 18

No, only removes subcutaneous fat (visceral is the one that matters)

Question 19

Effects of increased abdominal pressure

Answer 19

GERD, urinary incontinence

Question 20

Respiratory abnormalities

Answer 20

Obesity hypoventilation syndrome (OHS)

Reduced FRC, ERV, VC, and compliance of chest wall and lung

Breathing requires more energy, leads to progressive hypercapnia and hypoxemia

Also predisposes you to apnea

Question 21

Do obese people get eccentric or concentric cardiac hypertrophy?

Answer 21

Eccentric