Energy Balance

Question 1

Define respiratory quotient and name the quotients for carbs, protein, and fat.

Answer 1

vC02/v02

1. 0 - carbs
2. 85 - protein
3. 7 - fat

Question 2

What are the three components of total energy expenditure (TEE)? What are their relative proportions of TEE?

Answer 2

1. Basal energy expenditure (BEE) - 60-70%
2. Thermic effect on feeding (TEF) - 10-15%
3. Physical activity (EEPA) - 30-40%

Question 3

What is the major tissue determinant of basal energy expenditure (BEE)?

Answer 3

Fat free mass (FFM) aka lean mass

Question 4

Stimulation of the ____ _______ receptor can lead to the activation of uncoupling protein to increase heat production in adipose cells.

Answer 4

beta-3 adrenergic

Question 5

What is the primary hormonal determinant of BEE?

Answer 5

Thyroid hormone

Question 6

BEE drops ____% per year as a result of aging.

Answer 6

1-2%

Question 7

Foods rich in which macronutrient result in the highest thermic effect of feeding (TEF)?

Answer 7

Protein

Question 8

What are the two components of energy expenditure for physical activity (EEPA)?

Answer 8

1. Expenditure during exercise and excess post-exercise oxygen consumption (EPOC).
2. Non-exercise activity thermogenesis

Question 9

Basal energy expenditure can better adapt to ______feeding than to ______feeding.

Answer 9

Adapts better to underfeeding than to overfeeding.

Question 10

What is the non-homeostatic food intake mechanism?

Answer 10

The reward system

Question 11

Do leptin and insulin control long-term, or short-term food intake?

Answer 11

Long-term

Question 12

What nutrients do enteroendocrine cells detect and what do they send their signals through?

Answer 12

Detect carbs, amino acids, LCFAs and SCFAs. “Gut hormones” are sent to vagal neurons, spinal neurons, enteric neurons, and into fenestrated capillaries –> circulation.

Question 13

Is Ghrelin a peptide or steroid hormone?

Answer 13

Peptide

Question 14

Where is Ghrelin produced?

Answer 14

Stomach

Question 15

On what organ does Ghrelin act on?

Answer 15

Hypothalamus

Question 16

What does Ghrelin do?

Answer 16

Make you hungry

Question 17

People that are obese have _____ levels of ghrelin than people who are of normal weight.

Answer 17

Lower

Question 18

What hormone is thought to mediate the satiety gained through high protein diets?

Answer 18

CCK

Question 19

Can a very high protein diet increase risk for bone loss?

Answer 19

Yeah

Question 20

Where is CCK secreted from? In response to what?

Answer 20

Duodenum in response to protein and fat.

Question 21

What gastric effects result from CCK secretion?

Answer 21

Satiation and delayed gastric emptying

Question 22

What does CCK act on?

Answer 22

Vagus nerve

Question 23

How do high glycemic index foods result in more frequent eating?

Answer 23

The spike in insulin may actually cause hypoglycemia –> hunger

Question 24

Is there evidence to support long-term weight loss as a result of low glycemic index diets?

Answer 24

No

Question 25

Name three things that fiber does in the GI tract.

Answer 25

1. Delays emptying 2. Promotes stretch 3. Decreases the rates of absorption and digestion

Question 26

Name a benefit of delaying food digestion and absorption.

Answer 26

As food moves distally in GI tract, enteroendocrine cells become more frequent and they will secrete more GLP-1 and peptide YY (hormones)

Question 27

Where is GLP-1 made and what triggers its secretion?

Answer 27

Made by L cells in the small intestine in response to luminal macronutrient sensing and vagal input.

Question 28

What are the actions of GLP-1?

Answer 28

Delayed gastric emptying, incretin effect (glucose-dependent insulin secretion)

Question 29

Where is peptide YY made and what triggers its secretion?

Answer 29

Made by L cells in the distal small intestine and in the colon in response to luminal macronutrients.

Question 30

What are the effects of peptide YY?

Answer 30

Delayed gastric emptying, satiety.

Question 31

What three things affect the energy density of a food?

Answer 31

water, fat, fiber

Question 32

Which cells make leptin? What organ does it act on?

Answer 32

Adipose. Acts on hypothalamus.

Question 33

What does leptin do? Is its secretion proportional to fat stores?

Answer 33

Leptin is a satiety hormone. It is proportional to fat stores but people who are obese are less sensitive to the hormone.

Question 34

Non-homeostatic control (reward) is mediated by the ______ ______. Can it override homeostatic controls?

Answer 34

Limbic system. Can override homeostatic controls.

Question 35

What is the most common medical cause of obesity?

Answer 35

Polygenic

Question 36

How is leptin deficiency treated?

Answer 36

With leptin

Question 37

What is the melanocortin 4 receptor? What happens if it is mutated?

Answer 37

It is an MSH receptor somehow involved in the leptin signaling pathway. If mutated --> obesity; also associated with binge eating.

Question 38

What is ectopic fat distribution?

Answer 38

Accumulation of fat in organs

Question 39

What do FFAs and inflammatory cytokines from excess adipose do to insulin signaling?

Answer 39

They inhibit the GLUT4 receptor response.

Question 40

At what BMIs are weight loss medications indicated?

Answer 40

30 or greater or 27 or greater with comorbidities.

Question 41

When is weight loss surgery indicated?

Answer 41

40 or greater BMI (or 35 and up with comorbidities), less invasive treatments have failed, desired by patient.