Body-Weight Regulation

Question 1

(1)What is an obesogenic
environment? (2) Its
relationship to obesity?

Answer 1

1 - environment that helps contribute to obesity
2 - excessive food intake, unhealthy habits/options, sedentary behaviour

Question 2

What are examples of obesogenic environments? (4)

Answer 2

1 - Cost of healthy foods vs. unhealthy foods
2 - Sedentary jobs
3 - Unsafe communities
4 - Food deserts and food swamps

Question 3

What is driving obesity prevalence?

Answer 3

• genetic predisposition
• obesogenic environment

Question 4

What does the term
phenotype mean?

Answer 4

Observable trait: determined by genetic traits passed on from parents

Question 5

How does environment and
genetics interact to influence
body weight?

Answer 5

When food scarce = genetics don’t influence and there is little variations in phenotypes (thin)

When highly palatable food abundant = high % obese phenotype in those genetically prone and those somewhere in the middle

Question 6

What is the difference
between food deserts and
food swamps?

Answer 6

Deserts: neighborhoods where people have limited access to healthy/affordable food

Swamps: Neighborhoods where unhealthy food options prevail over healthy ones

Question 7

What do food deserts and food swamps account for?

Answer 7

Disparities in obesity rates among low-income populations and minority groups

Question 8

What makes adipose tissue
an endocrine gland?

Answer 8

It secretes hormones (adipokines)

Question 9

What are adipokines?

Answer 9

Hormones make by fat cells that come from adipose tissue.

Question 10

What are the important roles of adipokines? (3)

Answer 10

1 - Metabolism (regulating energy intake/expenditure)

2 -Reproduction

3 - Impact risk of disease

Question 11

How are hunger/satiety
different from appetite, food
cravings, and food
aversions?

Answer 11

Hunger/satiety = physical cues that initiate/terminate eating.

Appetite/cravings/aversion = stimuli that override physical cues that govern eating (psychological) - not caused by lack of nutrients.

Question 12

Food aversion

Answer 12

More than a dislike for food (associated with unpleasant experience)

Question 13

What is the role of the
hypothalamus in energy
intake and energy
expenditure?

Answer 13

Regulates:
1. energy intake (hunger, satiety, appetite)
2. energy expenditure

by releasing neuropeptides

Question 14

How do catabolic and
anabolic neuropeptides
influences energy intake and
energy expenditure?

Answer 14

ANP - promote weight gain by increasing hunger and decreasing energy expenditure.

CNP - promotes weight loss by decreasing hunger and increasing energy expenditure.

Question 15

Name short-term meal-related
peripheral signals that
communicate hunger and satiety to
the brain?

Answer 15

Neural: Gastric distention (satiety)
Hormonal - from GI tract: Ghrelin (hunger), CCK (satiety), glucagon (satiety)
Blood glucose/insulin levels.

Question 16

How did early parabiosis
experiments help lead to the
discovery of leptin? What causes
excessive weight gain in ob and db
mice?

Answer 16

-shared circulated blood

Question 17

Explain what happens when an ob
mouse is paired with a lean mouse?
Why?

Answer 17

ob loses weight, lean no change.

ob lacks satiety signal = obese.

When ob recieve satiety signal from lean mice = weight loss

Question 18

Explain what happens when a db
mouse is paired with a lean mouse?
Why?

Answer 18

No change in db mouse, but lean mouse starves to death.

db mouse produces satiety but unresponsive (obese, hyperphagic, inactive)

Lean mouse dies b/c excessive amount of satiety signal from db mice.

Question 19

Explain what happens when an ob
and db mouse are paired? Why?

Answer 19

ob loses weight, no change in db.

db produce satiety but unresponsive - satiety reaches ob and ob loses weight.

Question 20

(1)Where is leptin produced (2)how is it impacted by a person’s
adiposity?

Answer 20

1 - adipose tissue
2 - leptin levels reflect body’s energy reserve (in proportion to fat mass)

Question 21

What makes leptin levels
increase and decrease and what
affect does this have on weight
change?

Answer 21

Large fat mass: high leptin levels signal hypothalamus that energy reserves abundant. CNP increased. lower food intake higher EE = weight loss

Small fat mass: low leptin levels signal hypo. energy reserves low. ANP released. Higher food intake lower EE = weight gain.

Question 22

What is leptin resistance and how
does it relate to people that are
obese?

Answer 22

• Diminished response to elevated leptin release. = no signal = brain perceives starvation = EI increased = weight gain.

(reproduction dysfunction)

Question 23

What is the overall effectiveness of
dieting, bariatric surgery, and
Ozempic have short-term and long-
term on body weight?