Week 8: Obesity

Question 1

What is Obesity?

Answer 1

A condition in which the body’s energy stores are too large

Question 2

What BMI defines obesity?

Answer 2

> 30

Question 3

Why is metabolic syndrome a large problem in obese people?

Answer 3

Combination of clinical disorders: insulin resistance and leptin resistance.
- both are dysfunctions in hormone signaling
Disrupts ability to regulate weight

Question 4

What causes obesity?

Answer 4

By consuming too much fat and sugars and then not burning(using) the energy. This then leads to the body storing the extra energy as body fat.

Question 5

What cases account for most cases of obesity? and the least?

Answer 5

Chronic energy imbalance accounts for most cases of obesity in genetically susceptible individuals.
Metabolic disorders or disease account for only ~1% of obesity cases.

Question 6

What is the obesity susceptibility gene?

Answer 6

fat mass and obesity associated gene(FTO)
This gene may influence food intake and satiety(Bouchard 2008)

Question 7

Are there familial factors to obesity?

Answer 7

Children of obese parents do not have major defects in energy expenditure compared to those from non-obese parents
But, genetics x environment a vital factor

Question 8

What is an obesogenic environement?

Answer 8

an environment that makes unhealthy choices the easy choice.

Question 9

What is creeping obesity?

Answer 9

The slow but gradual gain of body fat over a prolonged period of time.
BMI 30 - excess 383 kcal day
BMI 40 - excess 1000 kcal day

Question 10

What is thermogenesis?

Answer 10

The body’s generation of heat

Question 11

What are the 3 factors that add up to total energy thermogenesis?

Answer 11

Basal Metabolic Rate (BMR)
Thermic Effect of Food (TEF)
Total Activity Thermogenesis (TAT) (EAT + NEAT)

Question 12

What is basal metabolic rate?

Answer 12

Minimal rate of metabolism needed to sustain life

Question 13

What is the thermic effect of food?

Answer 13

Energy cost of digestion
10% of food energy

Question 14

What is the total activity thermogenesis? What is EAT vs NEAT?

Answer 14

Exercise activity thermogenesis
- the energy cost of exercise (EAT)
Non-exercise activity thermogenesis
- energy cost of non-exercise activities (NEAT)

Question 15

What is important about predictive equations?

Answer 15

Based on mass
but
Do not differentiate between fat mass and muscle mass.
Precision is increased by modifiers.

Question 15

How much energy does each thermogenesis factor contribute to energy burned?

Answer 15

BMR = 60-80%
TEF = 10%
TAT 20–40%

Question 16

What is the equation for BMR?

Answer 16

Male = (15.3 x bodyweight(kg)) + 679 kcal
female = (14.7 x body weight) + 496 kcal

Question 17

What is the equation that factors in muscle mass? what is the name of these formulae? Why are these important?

Answer 17

katch-McArdle Forula (BMR)
= 370 + (21.6 x lean body mass)
Cunningham Formula (RMR)
= 500 + (22 x lean body mass)
- these are important because muscle mass is more metabolically active than fat mass.

Question 18

What is the Harris -benedict formula?

Answer 18

BMR x 1.25 = total caloric intake for moderately active people
x 1.5 for very active people

Question 19

What is adaptive thermogenesis?

Answer 19

Defined as the regulated productions of heat in response to environmental changes in temperature and/or diet; increase/decrease metabolic inefficiency
- hormonally regulated (adipose secreted hormones)

Question 20

Explain how the bidirectional negative feedback system affects thermogenesis.

Answer 20

It will slow body mass reduction during caloric deficit.
Slows body mass increase during caloric surplus.

Question 21

Explain the findings in the Levine (1999) study. Role of NEAT in Resistance to Fat gain in humans.

Answer 21

Fed subjects more food. the calculated weight gain was 7kg. The average weight gain was only 5kg. Ranged from 1.4-7.2kg. Changes in EAT were prohibited to limit change.
The large variability in inter-individual NEAT best explained fat gain.

Question 22

What is the role of adipokynes?

Answer 22

Enter circulation and interact with various brain centers. (hypothalamus)
They regulate adaptive thermogenesis.
- modify appetite.
- modify activity (EAT and/or NEAT)

Question 23

How does leptin work in the body?

Answer 23

There are circulating levels equivalent to adiposity.
provides information to brain regarding energy storage
Increased leptin secretion initiates negative feedback
- decreased appetite, increased activity

Question 24

Leptin Deficiency is not the problem. So why is leptin important?

Answer 24

Leptin Resistance is the main problem since leptin deficiency is so rare. Hypothalamus will not provide negative feedback when leptin is released. Leading to increased food intake and decreased energy expenditure.

Question 25

How does leptin resistance occur?

Answer 25

Due to chronically high leptin levels. This occurs from high adiposity tissue levels. This links obesity with metabolic syndrome.

Question 26

What prevents leptin resistance?

Answer 26

Physical activity.

Question 27

What are the macronutrient suggestions to target weight loss?

Answer 27

Decrease fat intake
Decrease simple carbs
Increase complex carbs

Question 28

What is recovery like following high intensity exercise?

Answer 28

Fat oxidation increases as body restores CHO
not an effective process

Question 29

What type of exercise produces a better increase in proportional kcal intake?

Answer 29

Moderate intensity exercise produces proportional increase in kcal intake.

Question 30

HIIT vs MICT programs. Which one caused a more significant fat mass and waist circumference decrease?

Answer 30

No significant difference however HIIT may be more time efficient. Running is better than cycling.

Question 31

REPS or STEPS? WHY?

Answer 31

isolated muscles produce a low normalized power, not doing much work
work time is low when doing resistance training
running will burn more energy.