Body Energy Balance

Front 1

What is meant by energy balance?

Back 1

Energy balance is the relationship between energy intake vs. output. Intake is the # of kcal we consume from food. Output is the kcal expended due to exercise, food processing, and body functions.

Front 2

What are the consequences of changing the balance between intake and output?

Back 2

If the intake > output, then we have weight gain. This is called positive energy balance. It results from eating more or exercising less.
If the intake < output, then we have weight loss, or negative energy balance. This happens through eating less or exercising more.
But if intake=output, we have energy equilibrium, which means the body has a constant weight.

Front 3

What is a bomb calorimeter? And what does it measure?

Back 3

It is a device used to measure the energy content of food. It does it by measuring the change in temperature of water as it increased due to energy output. We get energy output by igniting/burning the food through electrical charges. Side note: Remember that the body does not completely digest all fod and that it is unable to oxidize N for energy.

Front 4

Define hunger and appetite and how each influences food intake.

Back 4

Two factors that influence food intake and amt. are hunger and appetite.
HUNGER - is defined as the physiological desire to eat, when it is time to refuel. This is a complex process that involves hormones, neurotransmitters and physiological changes (moving nutrients in and out of cells)).
APPETITE - the psychological desire to eat; can occur in absence or presense of hunger; and it related to pleasant sensations associated with food.

Front 5

Define satiety and satiation and how each influences food intake.

Back 5

The other two factors that affect food intake and amt are satiety and satiation.
SATIATION - hormonal, physiological, and neural signsls that say "stop eating"; it develops during meal as a result of sensory stimulators and distention of stomach; proteins, carbs, and then fats in that order contribute to fullness
SATIETY - is the prolonged feeling of fullness between meals. It is a result of nutrient metabolism, which means eating fat prolongs satiety, but does not stimulate satiation.

Front 6

Describe the roles of hormones in regulating food intake.

Back 6

Acruate Nucleus Hormones:
These hormones reduce appetite when released: A-MSH and CART
These hormones stimulate appetite when expressed: NPY and AgRP

These hormones are affected by:
insulin-an increase suppresses NPY(desire to eat)

Other hormones affect hypothalamus directly:
leptin: fat cell hormone that tells I'm full. Stop eating. And so inhibits release of AgRP and in its place produces anorexigenic hormones
GI hormones like ghrenlin: Peptide hormone produced by stomach rises before eating and falls after eating. It stimulates releases of orexigenic hormones NPY and AgRP that trigger desire to eat.
PPY: inhibits NPY receptors, thereby reducing feeding

Front 7

Describe the roles of neurotransmitters in regulating food intake.

Back 7

Look above.

Front 8

Describe the roles of the hypothalamus in regulating food intake.

Back 8

The hypothalamus manages the regulation of food and satiety. It is THE CHIEF. It links temperate and eating behavior by making us eat in cold temperatures. It also houses the neurotransmitters that influence eating behavior through the direct or indirect effects by hormonal and neurological factors and drugs. In a region called the arcuate nucleus, two sets of neurons receive signals to release or express hormones. Other receptors. In another part, there is a receptor called the MC4R receptor that receives signals to increase or decrease feeding.

Front 9

What is resting metabolic rate? How is it measured? How is it estimated?

Back 9

In order to describe energy output for basal metabolism, we needed a value. That value is called the REE and we have that in kcal/day, or as the RMR. We can measure this through direct and indirect methods or estimate it with calculations like the Harris -Benedict equations and the abbrebiated method to estimate REE.
In the Harris-Benedict equation, the factors are age, height, weight, and gender. The ab. method use 1.0 for men and 0.9 for women to accomate men's more lean body mass.

Front 10

What factors increase and decrease RMR?

Back 10

The ones that INCREASE are: fever, physical stress, growth, high lean body mass, smoking, caffeine, large surface area, hyperthyroidism.
The ones that DECREASE are: aging, fasting, low lean body mass, hypothyroidism (thyroid hormone production is slow).

Front 11

What is direct calorimetry and give examples of measurement techniques.

Back 11

We measure the amt. of heat (or energy output) with the change in water temperatures. Heat production correlates directly w/ amt. of ATP the individual is using. For this, we need a metabolic chamber.

Front 12

What is indirect calorimetry and give examples of measurement techniques.

Back 12

This is measuring the CO2 production and/or O used. We can estimate the ATP being used, because as it is being used, CO2 production is a result at the same time. Plus, we also consume O. Examples are collecting respiratory gases through face mask and so and the doubly labeled water.

Front 13

What is considered the "gold standard" method for measuring energy expenditure? And why?

Back 13

The Doubly Labeled Water Method. Not only is in convenient, portable, it gives accurate results. Here, the subject drinks water with nonradioactive isotopes of H and O that are labeled. The O is excreted as: H2O and CO2 whereas the H is excreted as H2O. This measurement is easy. We look at where these isotopes go so we get a good idea of CO2 production. Its limitations are that it cannot give info about individual days or activities. With this method, scienist use the differencebetween the rate of H loss and O loss to calculate CO2 output and determine TEE.

Front 14

Define each of the components of energy expenditure and the relative contribution of each to total energy output. What factors influences each?
BASAL METABOLISM

Back 14

Basal metabolism - is all the types of energy we use just to function. It is 60-75% of total energy expenditure, giving us the most contribution. Age, gender, degree of muscle development, genetics, hormone levels, fever, and body size affect the REE.

Front 15

Define each of the components of energy expenditure and the relative contribution of each to total energy output. What factors influences each?
PHYSICAL ACTIVITY

Back 15

Physical activity - anything we do w/ out bodies beyond rest. It is the most variable of the 3 components and makes up 15-30% of total energy expenditure. Factors that influence this component of TEE are: energy cost of activity, body size (more E needed to move bigger person), and NEAT.

Front 16

Define each of the components of energy expenditure and the relative contribution of each to total energy output. What factors influences each?
THERMIC EFFECT OF FOOD

Back 16

Thermic effect of food - the energy it takes to digest, absorb, and transport the nutrients that we consume. It makes up less than 10% of the total energy expenditure. Factors include: protein and carbs require more energy to be stored becuz they need to be converted and macronutrient composition like amt. and variety.

Front 17

How can total energy expenditure or the TEE be estimated?

Back 17

It can be ESTIMATED very easily.
1. Find the resting energy using the gender factor.
2. Add on the activity factors (pg. 322).
3. Add on the thermic effect of food (this is 10% of the REE + Physical Activity).

Front 18

What factors are included in the EER equations?

Back 18

In the EER, or the Estimated Energy Requirements, the following factors are taken into consideration: Age (in years), Physical activity factor, Weight (in kg), Height (in m), and gender.

For the Harris-Benedict Equations, the factors are age, height, weight and gender.