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Chapter 2
Carbohydrates, Proteins, and Fats:
The Energy Macronutrients of
Balanced Meals
Macronutrients
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Macronutrients provide kilocalories (kcal),
a measure of energy
Carbohydrate (CHO) and protein (PRO) =
4 kcal/g
Fat = 9 kcal/g
Alcohol (ETOH) = 7 kcal/g; alcohol is not
considered macronutrient
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Macronutrients (continued)
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Macronutrients are organic—they all
contain carbon
Fats contain more carbon, thus being
higher in kilocalories
Being organic, all three macronutrients are
digestible—they can break down into
component molecules
All three macronutrients contain carbon,
hydrogen, and oxygen
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Foods Generally Contain a
Combination of Macronutrients
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Carbohydrates
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Made up of glucose molecules: C6H12O6
Three basic forms:
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Two sources:
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Sugar: monosaccharides and disaccharides
Starch: polysaccharides
Fiber: indigestible polysaccharide
Plants (from photosynthesis)
Milk
Chief energy source for the body cells
(sugar and/or starch)
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Examples
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Sugar is noted with suffix “ose”: glucose = blood sugar;
sucrose = table sugar; fructose = fruit sugar; lactose =
milk sugar
Glucose and fructose = monosaccharides
Starch = polysaccharide; found in bread, peas, corn,
pasta, and potatoes
Fiber = indigestible polysaccharide found in plants;
insoluble = skin and seeds and “crunchy” components;
soluble = pulp and “gummy” components
High-fiber foods have a relatively low glycemic index
Glycemic load: a meal with a high content of CHO with
sources that are high in glycemic index (quickly enter
the bloodstream)
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Food Label Guidelines
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60% kcal as CHO (300 g per 2000 kcal)
Total CHO = sum of sugar, starch, and
fiber
Fiber goal = 25 g per 2000 kcal
Net CHO = total CHO minus fiber and 1/2
sugar alcohols
*RDA for CHO: 130 g
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Estimating CHO Content
of Plant-Based Foods
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Assess 3 aspects of sensory experience of food:
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Level of sweetness
Level of water
Density
• ½ cup fruit (sweet): 15 g CHO
• ½ cup dry grains and dry (potato, legumes) or “sweet”
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vegetables (sweet corn, sweet peas): 15 g CHO
3 cups popcorn (low density): 15 g CHO
½ cup cooked or 1 cup raw low-CHO vegetables: 5 g CHO,
(most low CHO vegetables sound odd to say, “sweet _____”)
½ cup flour (very dry): about 45 g CHO
½ cup sugar (very dry and very sweet): about 100 g CHO
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Protein Attributes and Functions
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Protein is unique among nutrients because it
contains nitrogen
Because of its nitrogen content, protein is
used as a building source for new body cells
Protein is found in all body cells and
constituents such as the immune system,
hormones, and digestive enzymes
Dietary intake digested into amino acids; the
liver reassembles these into protein
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Protein Sources
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Found in muscle (i.e., red and white meats and fish),
eggs, nuts, legumes, milk, and milk products
Limited amounts in grains and vegetables
Only fats and sugars do not contain protein; fruit contains
only trace amounts of protein and is generally considered
to have none
Essential amino acids (EAA)—eight required for adults,
nine for children with need for histidine; certain quantity
needed in the diet within a 24-hour period to make
protein
Complete protein source: a food containing all eight
EAAs (animal products)
High-biologic value diet: emphasizes foods with all EAAs
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FYI Examples of EAA and Sources
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Methionine—primary source is animal protein;
metabolized into taurine and homocysteine;
contains sulfur; excess intake linked with bone
loss, some chronic diseases (cardiac,
Alzheimer’s, diabetes)
Phenylalanine—found in aspartame
(NutraSweet); all U.S. infants are tested for
phenylketonuria (PKU) at birth; caution on labels
aimed at individuals with PKU
Tryptophan—found in high amounts in turkey and
milk; precursor to the hormone serotonin (that
promotes a “good feeling” and helps induce sleep)
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Protein Needs
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Minimum of 50 g daily, with all EAAs
Individualized needs based on age and
other factors
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Infants: 2.24 g/kg body weight (BW)
Children: 1.5 g/kg BW
Adults: 0.8 g/kg BW
Older adults 1.0 to 1.2 g/kg BW
Athletes: 1.0 to 2.0 g maximum per kg BW
Increased needs also based on health
parameters (e.g., protein status or states of
increased demand, such as with burns)
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Protein Deficiency Conditions
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Reduced albumin (<3.5 mg/dL) related to
impaired body processes; (<2.8 mg/dL
related to poor surgical outcomes with
impaired wound healing and compromised
immune system)
Kwashiorkor: condition of protein deficiency
Marasmus, or protein-calorie malnutrition
(PCM)
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Estimating Protein Content of Foods
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1 oz meat (equals ¼ cup volume) = 7 g PRO
1 egg (¼ cup volume) = 7 g PRO
½ cup legumes, ¼ cup nuts, ¼ cup cheese
(1 oz) and 1 tbsp peanut butter are counted
as alternative to 1 oz meat
1 cup milk = 8 g PRO
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Fat (Lipids)
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Constituent of body cell membranes:
phospholipids
Essential fatty acids needed for hormonal
production (e.g., linoleic acid, an omega-6
fatty acid; alpha linolenic acid, an omega-3
fatty acid)
Precursor of hormone-like compounds:
eicosanoids
Solid = saturated fats; liquid = unsaturated
fats (monounsaturated and polyunsaturated)
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Degree of Saturation Can Be Determined
by Texture at Cold Temperature
General amounts of saturated fats, monounsaturated fats, and polyunsaturated fats can be determined by
appearance when fats are chilled. Note that solids are on the bottom of avocado and olive oils.
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Food Label Guidelines
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Fat based on 30% kcal (65 g/2000 kcal)
Saturated fat based on 10% kcal
(20 g/2000 kcal)
Trans fatty acids now listed; goal to have
intake as minimal as possible
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Made from the addition of hydrogen to liquid
oils; first commercial use of margarines and
shortenings in the 1940s
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Food Sources of Fat
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Found in germ portion of grains, some fruits
(e.g., coconut, avocado, olives), and in whole
milk (including butter), meats (including lard),
nuts and seeds, egg yolks
Omega-3 fatty acids (found in cold-water fish)
essential for brain development; plant forms
include flax, walnuts, canola oil
Monounsaturated fats are preferred source for
health (olive, canola oil and peanut oil, olives
and most nuts, avocado)
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Cholesterol
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A fatlike substance produced in the liver
Found only in animal fat
Not a kilocalorie source
Necessary for normal body functioning
Saturated fats can encourage excess
production of cholesterol by the liver;
unsaturated fats suppress the liver’s
production of cholesterol; these processes
are reflected in blood cholesterol levels
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To be discussed with review of Chapter 7
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Macronutrient Content of Food
Exchanges (Per 1 Serving on Average)
Food
Serv
CHO g
GRAIN
OR
STARCH
1 oz
15
FRUIT
½c
15
MILK
1c
VEG
½c
MEAT
1 oz
FAT
1 tsp
SUG
1 tsp
PRO g
FAT g
2
0
15
8
5 avg
5
2
7
LUNCH
PM
DINNER
H/S
5
4
54
19
15
Kcal
216
76
135
50%
18%
32%
@427
AM
5 avg
Total
% kcal
BKFST
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Sample Menu
Breakfast 1 starch:
1 milk:
1 fat:
1 sugar:
Lunch
2 starch:
1 meat:
1 fat:
2 veg:
1 milk:
2 sugars:
Dinner
1 starch:
2 fats:
3 meats:
2 veg:
1 fruit/sug:
1 milk:
1 slice toast
1 cup 2% milk
1 tsp butter
1 tsp jam
2 slices bread
1 oz turkey
1 tsp mayonnaise
1 cup mini-carrots
1 cup plain yogurt
2 tsp honey for yogurt
½ cup potato cooked in
AM 1 fruit: ½ cup grapes
PM 1 fruit: 1 orange
H/S 1 fruit/1 milk: 1 cup
strawberries with 1 cup 2% milk
2 tsp canola oil
3 oz ham
1 cup steamed cabbage
½ cup applesauce with 1 tsp cinnamon sugar
1 cup 2% milk
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Menu Planning Using
Food Exchanges
Example: Goal 2000 kcal at 55% CHO, 15% PRO,
30% fat
2000 kcal × 0.55 = 1100 kcal/4 = 275 g CHO
2000 kcal × 0.15 = 300 kcal/4 = 75 g PRO
2000 kcal × 0.30 = 600 kcal/9 = 66 g fat
To develop meal plan, start with number servings of
primary CHO foods (starch, fruit, milk; each
serving 15 g CHO)
Goal of 275 g CHO/15 = 18 total servings of
starch/fruit/milk; determine how many of each and
start doing the math
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18 Servings Starch, Fruit, Milk
Food
Serv
CHO g
GRAIN
OR
STARCH
11
165
FRUIT
4
60
MILK
3
PRO g
FAT g
22
~5
45
24
15
270
46
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BKFST
AM
LUNCH
PM
DINNER
H/S
VEG
MEAT
FAT
SUG
Total
kcal
% kcal
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Next Step: Add in
Non-Starch Vegetables
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2.5 cups vegetables = 25 g CHO (can
substitute for 1 serving of primary CHO
source (e.g., 1 starch)
Revise sums of macronutrients
Then determine amount of meat to meet
remaining PRO needs for predetermined
goal
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See Evolve for More
on Food Exchanges
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Complete food exchanges can be found in Evolve
Any food can be included into the Food
Exchanges that have similar macronutrient
content, for example:
1 oz potato chips = 15 g CHO and 10 g fat or 1 oz
potato chips = 1 bread and 2 fat servings
For Menu Planning:
Optimally low-fat/skim milk should be used in
calculations, with emphasis on lean meats and
unsaturated fats
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