Nutrition / Energy Balance

Question 1

causes of malnutrition

Answer 1

1. impaired access (poverty, immobility, disasters, famine, war; cultural / ethnic / traditional food preferences; poor dentition, eating disorders, anorexia)
2. impaired ingestion, digestion, absorption
3. impaired utilization

Question 2

essential macronutrients

Answer 2

*glucose
*amino acids (10 essential amino acids)
*fatty acids (linoleic and linolenic acid)

Question 3

sources of glucose

Answer 3

from sugars, starches, and complex carbs

Question 4

sources of amino acids

Answer 4

*protein
*10 essential amino acids: cannot be synthesized by must; must be acquired from the diet
*non-essential amino acid nitrogen

Question 5

sources of fatty acids

Answer 5

*from fats
*2 essential fatty acids: cannot be synthesized by body; must be acquired from diet:
-linoleic acid
-alpha-linolenic acid

Question 6

caloric contents of carbohydrates

Answer 6

4 kcal/gram

Question 7

caloric contents of protein

Answer 7

4 kcal/gram

Question 8

caloric contents of fat

Answer 8

9 kcal/gram

Question 9

caloric contents of alcohol

Answer 9

7 kcal/gram

Question 10

storage of glucose

Answer 10

*liver glycogen
*muscle glycogen

Question 11

storage of fat

Answer 11

*adipose tissue

Question 12

storage of protein

Answer 12

*muscle protein

Question 13

how are the macronutrients interconverted?

Answer 13

*all 3 macronutrients (glucose, amino acids, fatty acids) can be inter-converted by the LIVER

Question 14

post-prandial energy flux

Answer 14

*after eating a meal
*“storage mode” or anabolic mode
*anything leftover is stored as glycogen, adipose tissue, and muscle protein

Question 15

inter-prandial energy flux

Answer 15

1. mobilization of glycogen stores to support metabolism
2. minor release of fatty acids from adipose via lipolysis

Question 16

energy flux during an overnight fast

Answer 16

1. glycogen stores are gone
2. mobilization of fatty acids and amino acids; gluconeogenesis in liver

Question 17

energy balance =

Answer 17

*energy balance = caloric intake - total energy expenditure
*in disease states, we want energy balance to be NEUTRAL or POSITIVE (esp in acute illness)

Question 18

total energy expenditure (TEE)

Answer 18

30%: activity energy expenditure (AEE)
+
10%: thermic effect of food (TEF)
+
60%: resting energy expenditure (REE)

Question 19

resting energy expenditure

Answer 19

*the sum of basal metabolic energy expenditure and sedentary activities
*organ contribution to REE (LIVER 29%, brain 19%, muscle 18%, heart 10%, kidney 7%, fat < 1%)
*REE is proportional to Fat Free Mass (because fat is metabolically inert)
*REE is modified by many factors: age, gender, growth, hormones, smoking, disease, pregnancy

Question 20

physiologic factors affecting resting energy expenditure

Answer 20

*increase REE: growth, pregnancy, lactation, lean body mass
*decrease REE: aging, fasting

Question 21

pathological factors affecting resting energy expenditure

Answer 21

*increase REE: trauma/burns, inflammation, fever, sepsis, hyperthyroidism
*decrease REE: hypothermia, hypothyroidism

Question 22

thermic effect of food

Answer 22

*energy cost of absorption, digestion, and transport
*dietary fat requires 60 cal to convert to body fat
*dietary glucose requires 140 cal to convert to liver glycogen
*dietary protein requires 480 cal to convert ot muscle protein

AVERAGE TEE of a mixed meal = 200 cal

Question 23

measuring energy expenditure

Answer 23

*double labeled water
*direct calorimetry
*indirect calorimetry

Question 24

rule of thumb estimation of total energy expenditure

Answer 24

*based on:
1) BMI
2) level of activity

average = 30 kcal/kg of energy expenditure

Question 25

positive nitrogen balance

Answer 25

*requires sufficient intake of essential amino acids
AND
*requires sufficient TOTAL caloric intake (regardless of dietary protein intake)
*cannot be “forced” by intake of large amounts of protein or amino acids alone

Question 26

negative nitrogen balance

Answer 26

*negative nitrogen balance in catabolic stress can be mitigated (“protein sparing”) by giving:
-enough glucose to turn off gluconeogenesis
-enough amino acids to spare muscle protein

Question 27

clinical impact of protein/calorie malnutrition

Answer 27

*delayed post-surgical wound healing
*delayed recovery from severe trauma
*increased mortality in severe burns
*impaired immune response to infection
*increased toxicity of chemotherapy
*growth failure in pediatric patients