HS 251 - Energy Needs & Utilitzation

Positive Energy Balance & what it causes

Energy intake is more than energy expended

Weight gain - increased muscle mass & adipose tissue

What time periods is positive energy balance? (3)

pregnancy, childhood, adolescence

Negative Energy Balance and what does it cause?

energy expended (activity) more than energy intake

weight loss - body intake reduced (fat loss, muscle loss, loss of glycogen & bound water)

How much % does basal metabolic rate (BMR) take up in total daily energy expenditure (TDEE)?

50-70%

What are the 3 main components of the body’s energy needs?

1. Basal metabolic rate (BMR)

2. Thermic effect of food (TEF)

3. Thermic effect of exercise (TEE)

Thermogenesis

production of heat by body

Adaptive thermogenesis

body regulation of heat production

Basal Metabolic Rate (BMR)

energy to meet the body’s basic physiological needs

How does body composition affect BMR?

lean body mass (muscle) more metabolically active

How does age affect BMR?

BMR declines with age in adult years

How does pregnancy affect BMR?

higher BMR in pregnancy (about 15% higher)

How does gender affect BMR?

biological females have higher % body fat, smaller body size

How does body size affect BMR?

more surface area & heat loss, higher metabolic need

How does genetics affect BMR?

similar metabolic rates within families

How does emotional and physical stress affect BMR?

hormone response & healing increase BMR

How does thyroid hormones affect BMR?

low thyroid = low BMR

higher thyroid = higher BMR

How does nutritional status affect BMR?

starvation & fasting lower BMR

How does environmental temperature affect BMR?

body heat regulation metabolically expensive

How does caffeine & nicotine intake affect BMR?

slight increases w/ caffeine, more so with drugs

What is used instead of BMR since it is difficult to measure?

Resting metabolic rate (RMR)

Thermic Effect of Exercise (TEE)

increase in muscle contraction that occurs during physical activity

What does kcals needed for TEE depend on? (3)

activity performed

duration of activity

how much you weigh

Thermic Effect of Food (TEF)

energy used for digestion and absorption

used to process macronutrients & extracts kcals from foods

About —% of kcals in food used for TEF?

10

What is TEF influenced by? (3)

• meal composition & nutrients consumed

• athletic training decreases TEF

• Weight status

What are the environmental changes that affect body’s regulation of heat production? (3)

• Stress

• Temperature

• Diet

Direct Calorimetry

measures energy expenditure by assessing body heat loss within a metabolic chamber

Indirect calorimetry

estimates energy expenditure by measuring oxygen consumed & CO2 produced within a metabolic cart

What does Mifflin-St. Joer Equation estimate? What is based on?

Resting metabolic rate (RMR)

Based on gender, height, weight, age & requires an activity factor to determine estimated total energy per day

Mifflin-St. Joer Equation - Male

10*wt(kg) + 6.25*ht(cm) - 5*age(years) + 5

Mifflin-St. Joer Equation - Female

10*wt(kg) + 6.25*ht(cm) - 5*age(years) - 161

What does glucagon promote? (3)

• Glycogenolysis (in liver)

• Lipolysis (adipose tissue)

• gluconeogenesis (in liver, from non-carb sources)

breaking down glycogen & fat, promoting glucose

What does insulin promote? (3)

• Glycogenesis (storage in liver, muscle)

• Use of glucose by cells

• Lipogenesis (conversion of excess glucose to TG)

breaking down glucose, creating glycogen & fat

Hunger

sensation indicating physiological need for food

Appetite

desire to eat off with or without the presence of hunger

Satiety

sensation of fullneed after eating

Leptin

controls hunger & satiety in stomach

Insulin (stimulates + produced by)

Stimulates: satiety

Produced by: pancreas

Leptin (stimulates + produced by)

Stimulates: satiety

Produced by: adipocytes

Peptide YY (PYY) (stimulates + produced by)

Stimulates: satiety

Produced by: small intestine

Cholecystokinin (CCK) (stimulates + produced by)

Stimulates: satiety

Produced by: small intestine

Incretins (GLP-1 & GIP) (stimulates + produced by)

Stimulates: satiety

Produced by: small intestine

Neuropeptide Y (stimulates + produced by)

Stimulates: Hunger

Produced by: hypothalamus

Ghrelin (stimulates + produced by)

Stimulates: Hunger

Produced by: stomach

What are the physiological cues that prompt release of hormones? (3)

• stomach distension

• detection of entrance of protein, fat, CHO into small intestine

• hormones communicate signal for satiety to hypothalamus

Stomach distension

stretch receptors triggered

What is leptin quantity influenced by?

quantity of fat stores

Which 2 hormones work simultaneously on the hypothalamus?

Ghrelin & Neuropeptide (both hunger)

When are ghrelin levels higher? (3)

• fasting windows

• between meals

• during sleep