Nutrition - Chapter 7: Energy

How many calories are in each macronutrient?

Carbohydrates and Proteins: 4 kcals/g Fat: 9 kcals/g

How many calories are in alcohol?

7 kcal/gram

Catabolism

larger molecules are broken down into smaller ones; releases energy

Anabolism

small molecules are assembled into large ones (uses energy)

Energy in vs energy out

energy in: carbohydrates, protein, lipid, alcohol

energy out: - basal metabolism

- thermic effect of food

- physical activity

- = total energy expenditure

Energy Equilibrium

Energy intake equals energy expenditure, evening out body mass

Positive balance

more energy is available than expended; you can grow and replenish stores

Negative balance

energy expenditure exceeds intake; stored fuel contributes to the deficit

Total Daily Energy Expenditure (TDEE)

The number of calories used by an organism's body during a 24-hour period.

Basal Metabolic Rate (BMR)

energy used at rest to keep you alive (60 to 75% of TDEE)

Exercise Activity Therogenesis

planed exercise/workout

Non-Exercise Activity Thermogenesis

the energy expended for all activities not related to sleeping, eating, or exercise, including fidgeting, performing work-related activities, and playing

Thermic Effect of Food (TEF)

the energy expended as a result of processing food consumed

Hunger

the natural physical drive to eat, prompted by the body's need for food

Appetite

the psychological desire for food

Satiety

feeling of fullness

How do we get hunger and fullness cues?

Signals travel to and from the brain through the vagus nerve and bloodstream

What cues are sent to the hypothalamus?

stomach stretch, nutrient content, energy availability

Ghrelin

A hunger-arousing hormone secreted by an empty stomach

NPY

made in the hypothalamus to stimulate appetite in energy deficits

CCK

stimulates gall bladder to secrete bile to emulsify fats in the small intestine, gives short term fullness messages

GLP-1

hormone released after eating, promotes satiety, slows gastric emptying, enhances glucose absorption

Leptin

A hormone produced by adipose (fat) cells that acts as a satiety factor in regulating appetite (signals long term fullness)

Insulin

A hormone produced by the pancreas or taken as a medication by many diabetics

Cortisol

stress hormone that indirectly affects appetite by causing the bloodstream to redirect from rest and digest to fight and flight

body composition

the ratio of body fat to lean body tissue, including muscle, bone, water, and connective tissue such as ligaments, cartilage, and tendons

fat mass

body mass that is fat tissue (adipose tissue) that makes up energy storage, insulation, mechanical protection and endocrine function

lean tissue

muscle, bone, organs

fat distribution

- Amount of fat and distribution influenced by heredity and gender.

fat cells

cells that store nutrients (have a large reserve)

Dexascan (DXA)

bone density screening

Bod Pod

small chamber containing computerized sensors measures body composition by air displacement

BIA

sends a small electrical current through the body to estimate body fat (largely affected by hydration)

Skinfold calipers

Measure the thinkness of the fat layer on specific body sites.

BMI

Body Mass Index, a measure of body fat based on height and weight.

Lipolysis

the breakdown of fats and other lipids by hydrolysis to release fatty acids

Lipogenesis

the metabolic formation of fat

Hyperplasia

increase in cell number because fat cells are as big as possible and reach capacity

Weight Loss

fat cells shrink as fat is broken down, size goes down not number

Lipoprotein lipase (LPL)

an enzyme that hydrolyzes triglycerides passing by in the bloodstream and directs their parts into the cells, where they can be metabolized for energy or reassembled for storage.

Hormone Sensitive Lipase (HSL)

• Enzyme in the adipose cell that is responsible for the hydrolysis of triglyceride into FFAs and glycerol, which then leave the adipose cell and enter circulation

• Inhibited by the hormone insulin

Calorie Surplus

Increased calorie intake, a way to gain weight

Muscle Gain

protein synthesis > protein degradation (hypertrophy)

What are health consequences of obesity?

Strain on joints, blood sugar issues, heart strain, risk for chronic disease, reduced mobility/endurance

What happens in early days of fat release?

glycogen and associated water changes produce rapid initial weight changes

What happens in a sustained deficit?

Stored triglycerides provide fatty acids for energy (affects lean tissue as well)

How to preserve health in calorie deficit?

Maintain protein intake, resistance training, sleep (help preserve muscle)

HSL vs. LPL

HSL starts fat breakdown vs. LPL moves fat in or out of the bloodstream