Lesson 8

Define energy balance.

Traditional View: Energy in=Energy out

Modern view= Energy in* = Energy out ** (so much we dont know)

 The amount of energy the body derives from foods is called ________.

physiological fuel value

o Components of energy expenditure: Basal metabolism

all necessary involuntary physiological mechanisms required to sustain life like respiration, circulation, temperature regulation. 66% of energy is used. controlled by hormone thyroxine

oComponents of energy expenditure: Physical activity

anything that requires calories requires energy from food

o Components of energy expenditure:Thermic effect of food

The metabolic response to food is approximately 10% of the energy content of a meal

The TEF is typically greater for high-protein foods and for meals eaten all at once than spread out over a couple of hours

oComponents of energy expenditure: Adaptive thermogenesis

We have to spend extra energy to build tissues and hormones to cope with the extra demand

 Define basal metabolic rate (BMR). What factors raise or lower it?

all necessary, involuntary physiological mechanisms required to sustain life like respiration, circulation, temperature regulation

Age ⟶ lean body mass diminishes so this slows BMR

Height ⟶ tall, thin folks have higher BMR

Growth ⟶ periods of growth increase BMR

Body composition ⟶ with more lean tissue, higher BMR

Fever ⟶ increase

Stress ⟶ increase

Temperature (hot and cold) ⟶ increases

Fasting/starvation/malnutrition ⟶ lowers BMR

Smoking/caffeine ⟶ increases expenditure

Sleep ⟶ BMR lowest during sleep

 Define resting metabolic rate (RMR). How does it differ from BMR?

the amount of energy (in calories) your body burns at rest to maintain basic life-sustaining functions like breathing, circulation, and brain activity, as outlined on ACE Fitness.

• Basal Metabolic Rate (BMR):

• Measured under strict laboratory conditions.

• Requires an overnight stay or immediate measurement upon waking, at least 12 hours of fasting, complete physical and emotional rest, and a neutral room temperature.

• Represents the absolute theoretical minimum energy required to keep you alive.

• Resting Metabolic Rate (RMR):

• Measured under practical, less restrictive conditions.

• The subject rests quietly for a short period (e.g., 15 minutes) in a clinic or office without needing an overnight stay or a rigid 12-hour fast.

• Tends to be slightly higher (about 5% to 10%) than BMR because it includes minor background costs, such as the energy from traveling to the appointment, being awake, and slight digestive activity.

 What is the thermic effect of food, and what % of total expenditure does it account for?

10%

TEF of Macros + Energy Expended

Carbs ⟶ 5-10%

Fat ⟶ 0-5%

Protein ⟶ 20-30%

Alcohol ⟶ 15-20%

 Define adaptive thermogenesis and give examples.

the body's natural slowdown in metabolism and energy burning when you eat fewer calories or lose weight, which makes it harder to keep losing weight.

 During anabolism, what occurs?

simple molecules are combined to build larger, more complex molecules (such as proteins from amino acids or glycogen from glucose), which requires an input of energy (usually in the form of ATP

 During catabolism, what occurs?

breakdown of large, complex molecules into smaller, simpler units within living cells

 Define hunger, satiation, satiety.

• Hunger: The physical need or drive to eat caused by empty stomach signals and low energy.

• Satiation: The feeling of fullness that develops during a meal and tells you to stop eating.

• Satiety: The feeling of fullness and lack of hunger that lasts after a meal until it is time to eat again.

 Which part of the brain regulates appetite?

the hypothalamus

 Which hormones regulate appetite

ghrelin,: hunger regulating by stomach

leptin: satiation, promotes fullness

peptide YY: released by gut after a meal, works with glp1

CCK: Secreted by the small intestine in response to food, it helps signal meal termination and fullness.

 Which energy-yielding nutrient is the most satiating?

Proteins

 Define Body Mass Index (BMI) and know the formula in includes and lbs.

a measure of body fat based on height and weight

Equation: weight (lbs) / height² (inches) x 703 or weight (kg) / height² (meters)

 List BMI categories:

underweight, less than 18

healthy, 18.5-25

overweight, 25-30

obese. 30+

 Why is BMI limited as a measure of health?

BMI is based on weight/height/disease risk for individuals of European

descent (and mostly men!)

a. African American folks of all ages may have more lean tissue per pound

of body weight than Asians or Caucasians (meaning....?)

2. It is not an accurate predictor of health risk for many populations

3. It does not differentiate between lean body mass and body fat mass

a. For example, a very muscular person can have a high BMI but still have a

very low fat mass

4. And... it does not capture body fat location information

 Which methods can assess body composition

(skinfolds, DEXA, hydrodensitometry, bioelectrical impedance)?

 Which measure is used to gauge abdominal fat/central obesity?

Waist circumference and Waist to Hip Ratio

 Healthy waist circumference cutoffs for men and women.

Women: less than 35 inches (88cm)

men: less than 40 inches (102 cm)

 Define visceral fat vs. subcutaneous fat; which is riskier?

Visceral: (central) fat collected deep within the abdominal cavity (more riskier)

Subcutaneous: fat located right under the skin and can be found all around the body

 Define body composition.

a breakdown of your body's total weight into different components, primarily fat mass and fat-free mass (which includes muscle, bone, water, and organs)

 1 pount of fat contains roughly how many calories?

3500