Lecture 8

Question 1

What is true about obese individuals and metabolic rate?

Answer 1

They have high absolute metabolic rates.

Question 2

Why does obesity not decrease metabolism?

Answer 2

• Organs are larger and have to harder.
• More muscle mass increases metabolic rate.
• Energy cost for digestion is higher-eating more.
• Use more heat because larger surface area.
• Higher energy cost of movement.
• Adaptive Thermogenesis.

Question 3

What is Obesity?

Answer 3

An increase in body adipose( fat) tissue mass causing a condition in which the bodies energy stores are too large.

Question 4

What BMI is considered obese? Super obese?

Answer 4

Greater or equal to 30 - obese

Super obese- greater or equal to 50.

Question 5

What is metabolic syndrome?

Answer 5

Due to an interruption in hormonal signalling causing insulin and leptin resistance.

Question 6

Based on the clinical view, what causes obesity?

Answer 6

Chronic energy imbalance accounts for most cases of obesity in genetically susceptible individuals.

Question 7

What causes obesity based on the National Institute of Health?

Answer 7

If you consume high amounts of energy, particularly fat and sugars, but do not burn off the energy through exercise and physical activity much of the surplus of energy will be stored by the body as fat.

Question 8

Is there a obesity-suspectibility gene? If so, what is it? Is it based on genetics?

Answer 8

Studies in humans and rodents have suggested that the FTO may predispose to obesity and influence food intake and or fullness (satiety).

No based on genetics- children of obese parents do not have major defects in energy expenditure compared to those from non-obese parents.

Question 9

What are the consequences of those who are homozygous for the FTO risk allele.

Answer 9

Typically will weigh 3-4 kg more and are 1.7 more at risk for developing obesity.

Question 10

According to Frank Booth why are more and more people becoming obese?

Answer 10

We are living in an increasing obesogenic environment.

Question 11

What factors make up an obesogenic environment.

Answer 11

Decline of PA through driving to work, not a lot of physical chores around the house (dishwasher). And easy availability of energy dense foods and drinks quickly.

Question 12

What is creeping obesity?

Answer 12

The slow but gradual gain of body fat over a prolonged period of time.

Question 13

How can eating lots of food with inadequate energy expenditure affect our genes?

Answer 13

Good genes that turn on with exercise etc. can actually turn off.

Question 14

What is thermogenesis? What makes up the body’s total energy requirement?

Answer 14

The body’s generation of heat.

Energy Requirement:
BMR- basal metabolic rate.
TEF- Thermic effect of food.
TAT- total activity thermogenesis.

Question 15

Describe what BMR, TEF and TAT are. State the percentages of how they make total energy thermogenesis.

Answer 15

BMR- minimal rate of metabolism needed to sustain life. (30%)

TEF- energy cost of digestion. (10%)

TAT (60%) -
1) Exercise Activity Thermogenesis (EAT) - energy cost of exercise.

2) Non-Exercise Activity Thermogenesis (NEAT)- energy cost of non-exercise activities.

Question 16

What are the issues with BMI and why it is not always accurate.

Answer 16

Does not take into account differences in metabolic activity.

Does not distinguish between lean body mass and fat body mass - important because fat free mass is more metabolically active than fat mass.

Question 17

Why is the Harris-Benedict equation better than the BMR equation?

Answer 17

Factors in one’s activity level.

Question 18

What is adaptive thermogenesis? What is it controlled by?

Answer 18

Biochemical and physiological changes that alter resting metabolic rate in response to a chronic change in energy intake (linear).

Controlled by adipokynes.

Question 19

Why is adaptive thermogenesis seen as a survival mechanism?

Answer 19

Works to maintain body mass in face of long term caloric deficits and negative feedback that tries to keep weight constant.

Question 20

How does adaptive thermogenesis try to keep weight constant?

Answer 20

When individuals consume lots of calories, their BMR and thermic effect of food increases to prevent those from gaining lots of fat.

Question 21

What causes the variability in weight gain among the relationship of changing calories and BMR values?

Answer 21

Inter-personal variability in NEAT best explained gain in fat differences. This slows down but does not prevent weight gain.

Question 22

Is active thermogensis always working?

Answer 22

No there is an asymptote where it no long up-regulates or down-regulates to have a constant weight.

Question 23

Why are organs close to the visceral section of the trunk like the liver and kidney more susceptible to changes from adipokines.?

Answer 23

Individuals tend to store more fat there and therefore have a lot more circulating hormones in this area.

Question 24

What is the role of leptin?

Answer 24

Provides information regarding energy stores. It initiates negative feedback to decrease appetite and increase activity.

Question 25

Describe leptin resistance, a hallmark of metabolic syndrome.

Answer 25

Gaining weight because leptin levels are so high that receptors in the hypothalamus stop listening to leptin. Stop controlling weight through satiety.

Question 26

Why is exercise benefical for leptin resistance?

Answer 26

Prevents leptin resistance and ensure adaptive thermogenesis keeps working.

Question 27

What is the role of adaptive thermogenesis?

Answer 27

Slows weight gain in non-obese individuals.

Question 28

What is most important for weight loss?

Answer 28

Diet oppose to exercise. Specifically kcal restriction.

Question 29

If someone is wanting to lose weight, what should their macronutrient restrictions be?

Answer 29

• Decrease fat intake to decrease calories consumed and decrease risk of developing CVD disease.
• Decrease simple CHO to avoid metabolic syndrome.
• Increase complex carbs to support exercise.

Question 30

Is adaptive thermogenesis alone enough to support weight loss?

Answer 30

No, AT can slow down weight gain but exercise is still needed to sustain weight loss or maintain weight.

Question 31

What matters more, what you eat or how much you eat.

Answer 31

It matters how much you eat because that the end of the day kCal is a unit of heat and it does not matter where it comes from.

Question 32

Why is moderate intensity exercise the most effective for weight loss or management?

Answer 32

Moderate intensity activity produces proportional increase in kcal intake oppose to rapid and non-propotional off -sets.

Question 33

Why is eating CHO important for when trying to lose weight?

Answer 33

You want to eat CHO to reduce equivalence. IN between workouts the body prioritizes CHO stores and therefore it will expend fat to make more CHO.

Question 34

Even if structured exercise does not prevent weight loss on its own, why is it still important?

Answer 34

Preservation of muscle mass during periods of energy restriction.

Question 35

How many calories do you have to burn everyday to prevent creeping obesity?

Answer 35

500 kCal

Question 36

What is the relationship between muscle mass and obesity?

Answer 36

Maintaining or increasing muscle mass helps prevent creeping obesity BUT increasing muscle mass is not effective for acute weight loss.

Question 37

Why is energy expenditure during resistance training low?

Answer 37

Small working muscle mass (usually work isolated muscles).

Work to rest ratio is low.

Overall work time is low.

Normalised power is low.
Cost of protein synthesis is low.

Question 38

What type of exercise should you do if you want to expend lots of energy? Why?

Answer 38

Running!

The rate of whole body energy expenditure is 2-3 times greater for running than for strength training.

Question 39

Even though muscle is more metabolically active than fat, why is resistance training not lead to significant weight loss?

Answer 39

Looking at the body as a whole, it only accounts for 1/4 of our energy needs as protein synthesis is a very energy efficient process.