Bergdahl- Chapter 30 and 31 Flashcards
in general, what percentage of people are obese ?
1/3
who tends to gain the most weight ?
women
how much of the risk of becoming obese depends on genetic factors ?
80%
so do genes cause obesity ?
no, they instead lower the threshold for its development in a more susceptible environment
what genetic factor can be linked to obesity ?
congenital absence of leptin produced continual hunger and marked obesity in studies
what is leptin
a hormonal body weight-regulating substance produced by fat and released into the bloodstream that acts on the hypothalamus
what is the recommended amount of physical activity / day ?
30-60 min
what are the 5 specific risks of excessive body fat ?
1) impaired cardiac function from increased mechanical work
2) hypertension, stroke, DVT
3) increased insulin resistance, type II diabetes
4) renal disease
5) sleep apnea, pulmonary disease (due to added effort to move chest wall)
what are the three ways to measure fat ?
1) percentage of body mass composed of fat
2) distribution of fat in different anatomic regions
3) size and number of individual fat cells
what is the standard fat percentage for overfatness in men and women ?
men: over 20%
women: over 30%
what waist-to-hip girth ratios increase risk of death ?
men: 0.95
women : 0.8
what is central/ android-type obesity ?
fat deposits in abdominal area, internal visceral deposits
greater health risk
what are the two ways adipose tissue mass increases ?
1) fat cell hypertrophy
2) fat cell hyperplasia (number)
when you lose weight, what happens in the adipose tissue ?
shrinkage of adipocytes with no change in cell number
when you gain weight, what happens in the adipose tissue ?
enlarges existing adipocytes
what is the best way to weight control ?
following the 1st law of thermodynamics (weight loss occurs whenever energy output exceeds energy intake, regardless of macronutrient mixture)- a healthy diet, moderately reduced food intake
what brain area controls our level of weight/body fat within a tight range ?
hypothalamus
how can exercise control the hypothalamus differently than diet ?
exercise and drugs can change a person’s setpoint, but dieting has no effect. in dieting, everytime body weight decreases below the certain setpoint, there are internal adjustments that resist the change to conserve and replenish body fat
what is the biologic feedback mechanism that makes it hard to lose weight ?
when fat people lose weight, adipocytes increase their level of fat-storing enzyme, which facilitates body fat synthesis, and the fatter the person, the greater the production of the enzyme LPL
what are ketogenic diets and why are they bad ?
carb restriction while ignoring total calories (limit to 20g/day)
- this generates excess plasma ketone bodies, acidosis since fat is being used more as an energy source
- this aggravates kidneys, depletes glycogen reserves, causes dehydration, etc