Ch 8 Energy Balance and Body Composition

What is energy balance?

When energy intake = energy expended.

Result: stable body weight.

What happens during energy imbalance?

weight changes occur (gain or loss)

Changes in fat, water, lean tissue, bone minerals

How many kcals are in 1 lb of fat?

3500 kcals

What is the recommended rate of healthy weight loss?

1-2 lbs per week

Aim to lose 75% fat and 25% lean body mass

Starvation

protein and fat loss is 50% /50%

Adipose (fat) tissue is NOT

metabolically active

muscle tissue IS

metabolically active, even at rest

Can hold more kg/l

Apetite

desire to eat how much and how often

hunger

physiological need for food

triggered by nerve signals in hypothalamus

What horomone stimulates hunger?

Ghrelin

What hormone increases satiety?

Leptin

What nutrient is most satiating 

Protein

Satiation

• Stomach stretches in response to food

• CCK released 

• Fullness signals to brain STOP EATING

What environmental factor decreases food intake?

Heat

Which environmental factor increases food intake?

Cold

What are the three components of energy expenditure?

• Basal metabolism

• Physical activity

• Thermic effect of food.

Fructose is an apetite

stimulant

Which foods are satiating

High fiber foods

What sends strong satiety signals but aren’t satiating themselves 

High fat foods 

Thermogenesis

generation of body heat;meausre amount of energy expended

What is basal metabolic rate (BMR)?

The rate of energy used for life-sustaining activities while at rest.

What percentage of energy is used for BMR?

50-65%

What affects BMR?

Age, height, sex, body composition, fever, stress, temperature, fasting, hormones, smoking, caffeine, sleep.

What is the thermic effect of food/ (TEF)

Energy used to digest and absorb food

~10% of total energy expenditure.

What is the most variable form of energy expenditure?

Physycal activity

What is BMI, how is it calculated?

BMI = weight (kg) / height² (m²)

it estimates weight relative to height.

What are the BMI classifications?

Underweight: <18.5

Healthy: 18.5–24.9

Overweight: 25–29.9

Obese: ≥30.

Central obesity?

Fat stored around organs (visceral fat) linked to higher disease risk.

What is adaptive thermogenesis?

Calories burned when conditions in the body are dramatically changed. 

What waist circumference indicates increased health risk?

 Females: ≥35 inches

Males: ≥40 inches

Subcutaneous fat

stored in hips and thighs, more cardio protective (pear shape/gynoid)

2 places fat is distributed

Visceral and subcutaneous tissue

what health risks are associated with underweight?

Infertility, menstrual irregularities, osteoporosis, low disease resistance

Healthy weight?

Enough adipose tissue required to meet basic needs but not to incur risks.]

weight ALONE notindicator of health 

Health risks associated with excess body fat?

Increased risk of CVD, diabetes, cancer, reduced life expectancy.

what is metabolic fitness

A measure of health that considers cardiovascular and metabolic health, not just weight.

Can someone be overweight and metabolically healthy?

Yes, fitness and health vary across the BMI spectrum.

Pro of BMI

quick

best to asses populations, not individuals 

Cons of BMI

Only method used to classify body weight in clinical setting

stigmatizing

inaccurate measure of overall body health

Misleading for thin/fat bodies