Obesity Causes and Consequences

Question 1

Which children are at a higher risk of obesity? (2)

Answer 1

. Small for date infants (controlled by in utero environment)
. Children who are overweight under the age of 5 years old, with at least one or both parents being overweight
. Also, overweight teenagers are more likely to develop into obese adults

Question 2

Which factors put some females at a higher risk of obesity? (3)

Answer 2

Pregnancy, oral contraceptive, menopause

Question 3

What is the general pattern for weight gain in males?

Answer 3

. Usually progressive increase in weight until 60s, weight stabilises between 55 and 64 years and then slowly declines
. Bit of weight gain in mid-years due to reduced activity and increased calorie intake

Question 4

Give 3 lifestyle factors that can contribute to weight gain.

Answer 4

Sleep deprivation, smoking cessation (nicotine withdrawal leads to increased hunger), drugs (e.g. antidepressants, beta-blockers etc.)

Question 5

Give 4 illnesses that induce weight gain.

Answer 5

Hypothyroidism, polycystic ovarian syndrome, Cushing’s syndrome, hypothalamic obesity (extreme insatiable appetite)

Question 6

Give 4 monogenic causes of obesity.

Answer 6

Melanocortin-4-receptor defect, POMC gene defect, leptin defect, leptin receptor defect

Question 7

What is a MC4R defect?

Answer 7

Melanocortin-4-receptor defect- associated with early onset obesity and taller than average height

Question 8

What is a POMC defect?

Answer 8

Adrenal crisis in infancy leads to hyperphagia (insatiable appetite and excess eating) and thus obesity

Question 9

What is leptin? What is the effect of a leptin gene defect?

Answer 9

Leptin is a hormone produced by adipocytes to inhibit hunger and give a sense of satiety. It signals to the brain the extent of fat in storage. Leptin defect associated with hyperphagia due to still feeling hungry and thus can lead to obesity.

Question 10

What is a leptin receptor defect?

Answer 10

Leptin not detected so brain doesn’t receive signal or being full, leads to hyperphagia and obesity

Question 11

What are ob/ob mice?

Answer 11

Mice with leptin defiency

Question 12

What are db/db mice?

Answer 12

Mice with leptin receptor defect

Question 13

What is the range for a normal BMI? What is the range for being obese?

Answer 13

Normal is 18.5-24.9

Obese is 30-39.9

Question 14

Give three ways of assessing if someone is obese.

Answer 14

BMI, waist measurement, waist to hip ratio

Question 15

What is visceral fat?

Answer 15

Deep fat in the abdominal cavity packed around organs

Question 16

Why can visceral fat be dangerous?

Answer 16

. Excess visceral fat is associated with metabolic syndrome
. Metabolic syndrome means increased risk of hypertension, hyperlipidaemia (lots of fats and cholesterol in blood), impaired glucose tolerance which can progress to Type II Diabetes, CV problems
. Visceral fat also releases cytokines and hormones that can lead to insulin resistance and endothelial cell dysfunction and inflammation

Question 17

What is considered a safe and sustainable rate of weight loss and how is this achieved?

Answer 17

. 0.5-1 kg (1-2lb) per week weight loss. This can be achieved by reducing calorie intake by 600 calories a day
. For most men, no more than 1,900 calories a day
. For most women, no more than 1,400 calories a day

Question 18

Name two diet programmes that are generally considered unsafe unless supervised and monitored.

Answer 18

FAD diet (involves fasting and cutting out certain food groups) and VLCD (very low calorie diet)

Question 19

How much exercise is recommended?

Answer 19

150 moderate exercise per week or 75 minutes intense exercise per week.

Question 20

What is Orlistat?

Answer 20

Intestinal lipase inhibitor, reduces fat absorption

Question 21

What is Liraglutide?

Answer 21

Reduces hunger by delaying gastric emptying

Question 22

How does bariatric surgery influence weight loss?

Answer 22

Maximal weight loss seen 1-2 years after surgery, then weight increase occurs, which levels off after 8-10 years

Question 23

Which organ releases ghrelin and what effect does ghrelin have?

Answer 23

Stomach, increases appetite

Question 24

Which cells release leptin and what effect does leptin have?

Answer 24

Adipocytes, decreases appetite (satiety)

Question 25

Give the organs involved in increasing and decreasing appetite.

Answer 25

. Stomach secretes ghrelin, which increases appetite

. Adipocytes, pancreas, small and large intestines secrete hormones which decrease appetite