Lecture 8 Flashcards
(39 cards)
What is true about obese individuals and metabolic rate?
They have high absolute metabolic rates.
Why does obesity not decrease metabolism?
- 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.
What is Obesity?
An increase in body adipose( fat) tissue mass causing a condition in which the bodies energy stores are too large.
What BMI is considered obese? Super obese?
Greater or equal to 30 - obese
Super obese- greater or equal to 50.
What is metabolic syndrome?
Due to an interruption in hormonal signalling causing insulin and leptin resistance.
Based on the clinical view, what causes obesity?
Chronic energy imbalance accounts for most cases of obesity in genetically susceptible individuals.
What causes obesity based on the National Institute of Health?
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.
Is there a obesity-suspectibility gene? If so, what is it? Is it based on genetics?
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.
What are the consequences of those who are homozygous for the FTO risk allele.
Typically will weigh 3-4 kg more and are 1.7 more at risk for developing obesity.
According to Frank Booth why are more and more people becoming obese?
We are living in an increasing obesogenic environment.
What factors make up an obesogenic environment.
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.
What is creeping obesity?
The slow but gradual gain of body fat over a prolonged period of time.
How can eating lots of food with inadequate energy expenditure affect our genes?
Good genes that turn on with exercise etc. can actually turn off.
What is thermogenesis? What makes up the body’s total energy requirement?
The body’s generation of heat.
Energy Requirement:
BMR- basal metabolic rate.
TEF- Thermic effect of food.
TAT- total activity thermogenesis.
Describe what BMR, TEF and TAT are. State the percentages of how they make total energy thermogenesis.
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.
What are the issues with BMI and why it is not always accurate.
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.
Why is the Harris-Benedict equation better than the BMR equation?
Factors in one’s activity level.
What is adaptive thermogenesis? What is it controlled by?
Biochemical and physiological changes that alter resting metabolic rate in response to a chronic change in energy intake (linear).
Controlled by adipokynes.
Why is adaptive thermogenesis seen as a survival mechanism?
Works to maintain body mass in face of long term caloric deficits and negative feedback that tries to keep weight constant.
How does adaptive thermogenesis try to keep weight constant?
When individuals consume lots of calories, their BMR and thermic effect of food increases to prevent those from gaining lots of fat.
What causes the variability in weight gain among the relationship of changing calories and BMR values?
Inter-personal variability in NEAT best explained gain in fat differences. This slows down but does not prevent weight gain.
Is active thermogensis always working?
No there is an asymptote where it no long up-regulates or down-regulates to have a constant weight.
Why are organs close to the visceral section of the trunk like the liver and kidney more susceptible to changes from adipokines.?
Individuals tend to store more fat there and therefore have a lot more circulating hormones in this area.
What is the role of leptin?
Provides information regarding energy stores. It initiates negative feedback to decrease appetite and increase activity.
