Week 8: Obesity Flashcards
What is Obesity?
A condition in which the body’s energy stores are too large
What BMI defines obesity?
> 30
Why is metabolic syndrome a large problem in obese people?
Combination of clinical disorders: insulin resistance and leptin resistance.
- both are dysfunctions in hormone signaling
Disrupts ability to regulate weight
What causes obesity?
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.
What cases account for most cases of obesity? and the least?
Chronic energy imbalance accounts for most cases of obesity in genetically susceptible individuals.
Metabolic disorders or disease account for only ~1% of obesity cases.
What is the obesity susceptibility gene?
fat mass and obesity associated gene(FTO)
This gene may influence food intake and satiety(Bouchard 2008)
Are there familial factors to obesity?
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
What is an obesogenic environement?
an environment that makes unhealthy choices the easy choice.
What is creeping obesity?
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
What is thermogenesis?
The body’s generation of heat
What are the 3 factors that add up to total energy thermogenesis?
Basal Metabolic Rate (BMR)
Thermic Effect of Food (TEF)
Total Activity Thermogenesis (TAT) (EAT + NEAT)
What is basal metabolic rate?
Minimal rate of metabolism needed to sustain life
What is the thermic effect of food?
Energy cost of digestion
10% of food energy
What is the total activity thermogenesis? What is EAT vs NEAT?
Exercise activity thermogenesis
- the energy cost of exercise (EAT)
Non-exercise activity thermogenesis
- energy cost of non-exercise activities (NEAT)
What is important about predictive equations?
Based on mass
but
Do not differentiate between fat mass and muscle mass.
Precision is increased by modifiers.
How much energy does each thermogenesis factor contribute to energy burned?
BMR = 60-80%
TEF = 10%
TAT 20–40%
What is the equation for BMR?
Male = (15.3 x bodyweight(kg)) + 679 kcal
female = (14.7 x body weight) + 496 kcal
What is the equation that factors in muscle mass? what is the name of these formulae? Why are these important?
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.
What is the Harris -benedict formula?
BMR x 1.25 = total caloric intake for moderately active people
x 1.5 for very active people
What is adaptive thermogenesis?
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)
Explain how the bidirectional negative feedback system affects thermogenesis.
It will slow body mass reduction during caloric deficit.
Slows body mass increase during caloric surplus.
Explain the findings in the Levine (1999) study. Role of NEAT in Resistance to Fat gain in humans.
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.
What is the role of adipokynes?
Enter circulation and interact with various brain centers. (hypothalamus)
They regulate adaptive thermogenesis.
- modify appetite.
- modify activity (EAT and/or NEAT)
How does leptin work in the body?
There are circulating levels equivalent to adiposity.
provides information to brain regarding energy storage
Increased leptin secretion initiates negative feedback
- decreased appetite, increased activity
Leptin Deficiency is not the problem. So why is leptin important?
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.
How does leptin resistance occur?
Due to chronically high leptin levels. This occurs from high adiposity tissue levels. This links obesity with metabolic syndrome.
What prevents leptin resistance?
Physical activity.
What are the macronutrient suggestions to target weight loss?
Decrease fat intake
Decrease simple carbs
Increase complex carbs
What is recovery like following high intensity exercise?
Fat oxidation increases as body restores CHO
not an effective process
What type of exercise produces a better increase in proportional kcal intake?
Moderate intensity exercise produces proportional increase in kcal intake.
HIIT vs MICT programs. Which one caused a more significant fat mass and waist circumference decrease?
No significant difference however HIIT may be more time efficient. Running is better than cycling.
REPS or STEPS? WHY?
isolated muscles produce a low normalized power, not doing much work
work time is low when doing resistance training
running will burn more energy.
