Chapter 72 - Dietary Balances Flashcards
Energy Available in Food
(1) Carbs
(2) Fat
(3) Protein
(1) Calories - 4.1; Ave. Absorbed - 98%
(2) Calories - 9.3; Ave. Absorbed - 95%
(3) Calories - 4.35; Ave. Absorbed - 92%
Percentage of Energy from Average American Diet
(1) Carbs
(2) Fat
(3) Protein
(1) 45%
(2) 40%
(3) 15%
Percentage of Energy from Average Non-Western Diet
(1) Carbs
(2) Fat
(3) Protein
(1) 80%
(2) 15 - 20%
(3) 15 - 20%
Average daily requirement of protein
30 to 50 grams
Average number of proteins degraded daily
20 to 30 grams
Corn is a partial protein with inadequate amounts of essential amino acids - ; strict single diet of corn can lead to what disease?
Tryptophan and lysine
Kwashiorkor
Food legumes are partial proteins containing essential amino acids rich in (1) and deficient in (2)
(1) tryptophan and lysine
(2) methionine
Respiratory Quotient
The ratio of carbon dioxide production for every oxygen molecule utilization during the metabolism of 1 gram of (carbohydrate, fat, or protein)
Respiratory Quotient of (1) carbohydrate, (2) fat, (3) protein
(1) carbohydrate = 1.0
(2) fat = 0.70
(3) protein = 0.80
Method to determine the metabolic utilization of Carbohydrate, Fat, and Protein for different foods
Respiratory Quotient
Where after consuming a meal,
a RQ of 1 will mean exclusive carb metabolism and 0.7 exclusive fat metabolism
Since protein metabolism is normally small, a RQ between 0.7 and 1 will describe approximate ratios of carbohydrate to fat metabolism
Accurate measurement of protein metabolism can be via measuring nitrogen excretion via urea
Important findings from respiratory quotient studies
After a mixed meal
1. Carbohydrates are exclusively metabolized immediately
(RQ=1.0)
2. After 8 to 10 hrs, fats are metabolized (RQ = 0.70)
3. In times where carbs cannot be metabolized (diabetes mellitus) fats are metabolized (RQ = 0.70)
Percent of nitrogen in protein
16% or 6.25 (as 100/16)
Percent of nitrogen excretion during protein metabolism in (1) urine as urea, uric acid, and other nitrogen products and in (2) feces
(1) 90%
(2) 10%
Computation of protein metabolism (in grams) by measuring amount of nitrogen in urine
[(nitrogen in urine)*(1 + 0.1)] * 6.25
The average percentage of energy ingested that normally reaches the functional system of the cells
27%
Energy expenditure (in calories) of a (1) sedentary person and (2) athletes and laborers
(1) 2, 000 cal
(2) 10, 000 cal
The desire for food
Appetite
Neuronal Centers in the Hypothalamus for Feeding and Diet Balance
- Lateral nuclei (feeding center)
- Ventromedial nuclei (satiety center)
- Paraventricular nuclei
- Dorsomedial nuclei
- Arcuate nuclei
….nuclei of the hypothalamus
Site in the hypothalamus where multiple hormones released from the gastrointestinal tract and adipose tissue (nervous and peripheral signals) converge to regulate food intake as well as energy expenditure (from energy stores)
Arcuate Nucleus
Feeding center of the hypothalamus
Lateral nuclei of the hypothalamus
Major satiety center of the hypothalamus
Ventromedial nuclei of the hypothalamus
Lesion (destruction) in this area of the hypothalamus causes excessive food intake
Paraventricular nuclei of the hypothalamus
Lesion (destruction) in this area of the hypothalamus depresses eating behavior
Dorsomedial nuclei of the hypothalamus
Condition characterized by marked weight loss, muscle weakness, and decreased metabolism
inanition
Two types of neurotransmitters that the hypothalamus has high density of receptors for
- orexigenic substances - stimulate feeding
(o for open mouth during eating) - anorexigenic substances - inhibit feeding
(anorexia so thin not eating)
Most common known monogenic (single-gene mutation) causes of human obesity
Studies suggest it is responsible for 5% to 6% of early-onset severe obesity in children
POMC and MCR-4 receptor
Controls the actual mechanism of feeding
Brainstem
Centers of the brain that work together to control feeding and appetite
- Hypothalamus
- Amygdala
- Prefrontal cortex
Destruction of this area causes “psychic blindness” in the choice of food - loss of part of the appetite control that determines the type and quality of food it eats
(part of the olfactory system)
amygdala
FACTORS THAT REGULATE QUANTITY OF FOOD INTAKE
- short-term regulation
- long-term regulation
Theories involving blood concentrations of glucose, AA, and fats in the long-term regulation of food intake
- glucostatic theory of hunger and feeding regulation
- aminostatic theory of regulation
- lipostatic theory of regulation
Another Obesity causing condition regarding long-term regulation mechanisms of food intake
Considered a rare monogenic mutation
leptin resistance
mutation in leptin receptors
Helps maintain constant stores of nutrients in the tissues preventing them from becoming too low or too high
Long-term Regulation of Food Intake
BMI formula
BMI = (Weight in Kg) / (height in m ^2)
BMI Range for Overweight
*(WHO) 25 to 29.9
*(Asia-Pacific) 23 to 24.9
BMI Range for obese
greater than or equal to 30
Indicators for abdominal obesity (waist circumference)
Men: > 102 cm
Women: > 88 cm
Indicators for abdominal obesity (waist/hip ratio)
Men: > 0.9
Women: > 0.85
Drug that directly inhibits feeding centers in the brain
amphetamine
A sympathomimetic drug that reduces food intake and increases energy expenditure
phentermine & sibutramine
