Energy Balance
energy in =energy out
- a shift in balance causes weight change
- rapid changes are gradual
excess energy stored as fat
- fat is used as fuel between meals
- 20% of lost weight is lean mass
- to lose 1 pound, need to expend extra 3500 kcals than your body needs
- all gets broken down to acetyl CoA and turned to fat
Appetite
Energy In: food consumption
bomb calorimetry
- as foods burn - heat, CO2 and water
-calc the cals from energy-yielding nutrients
- amount of heat/how it burns = how many cals
1kcal of energy needed to heat up 1 kg of water by 1 degree
Hunger
Satiation
stop eating, feeling of fullness
- exercise - makes you not wanna eat
Satiety
- overriding factors - stress, boredom, socialization, easy access
Energy out: components of energy expenditure
thermogenesis: production of energy - releasing heat
- basal metabolism - amount of energy body needs every day to maintain base
RMR- resting metabolic rate
BMR- basal metabolic rate. Very base rate of food you need. Measured first thing in the morning
Food consumption
thermic effect of food -> warm feeling after eating. Body needs energy to digest and absorb nutrients. Normal meal doesn’t raise too much. More w a big meal
adaptation responses
metabolism during an infection.
metabolism is higher, body is trying to keep homeostatic state
Factors influencing energy out
factors that decrease the BMR
Estimating energy requirements
influenced by:
Physical activity factors
Sedentary: typical daily activities
Low Active: 30-60 mins moderate activity
active: 60 mins or moderate activity or more
very active: 60 mins of moderate activity and 60 mins vigorous activity or 120 moderate
BMI calculation
relative weight for height BMI = weight (kg) height (m^2) underweight: <18.5 healthy weight: 18.5-24.9 overweight: 25.0-29.9 obese: 30.0+
Muscle mass
BMI doesnt include muscle mass
Body fat distribution
Fat distribution
visceral fat: the real problem for metabolic diseases
- central obesity
subcutaneious fat
Waist circumference
Indicator of visceral fat - fat surrounding organs
Health risks associated with body weight and body fat
risks associated with being underweight
fighting against wasting diseases (cancer)
menstrual irregularities and infertility
osteoporosis and bone fractures
BMI and mortality
BMI 22.5-24.9 optimal
BMI 30-34.9 = 3 years loss of life
BMI >40 = 10 years loss of life
Skin Folds
Hydro Densitometry
weight yourself on land and in tub of freezing cold water, dunk yourself completely under water
- difference between 2 weights is indicative of body volume
Bioelectrical impedance