Chapter 5: Lipids: Fats, Phospholipids, and Sterols
EXCI 204 — Food for Sport · Chapter Study Notes (with formulas & calculations)
Chapter Overview
Lard — an animal fat from swine — was until relatively recently the principal fat Americans used to
prepare food; in the 1800s the fat from salt-cured pork went into everything from soap to candles.
During the Long Depression of the 1870s, William Procter and James Gamble sought cheaper fats for
soap and settled on palm and coconut oil (→ Ivory soap, so high in fat it floated). They then turned to
cottonseed oil, a textile waste product. A German chemist’s 1907 process — hydrogenation — made a
solid fat from a liquid oil, leading to Crisco, which replaced virtually every tub of lard. Almost a century
later it was recognized that the trans fats in hydrogenated oils increase heart disease risk, which led the
FDA to remove them from foods.
The chapter covers: (5.1) fats in our food; (5.2) triglycerides and fatty acids, phospholipids, and sterols;
(5.3) lipid digestion, absorption, and transport by lipoproteins; (5.4) lipid functions — essential fatty
acids, eicosanoids, and fat as energy; (5.5) lipids in heart disease, cancer, and obesity; and (5.6) fat and
cholesterol recommendations, choosing fats, food labels, and fat replacers. This chapter contains
several calculations (% of calories from fat, label % DV, “percent lean”) — each is boxed as a FORMULA
where it appears and collected at the end.
KEY CONCEPT ⭐
Energy values you need for this chapter
• Fat = 9 Calories/gram — more than twice carbohydrate or protein.
• Carbohydrate = 4 Calories/gram; protein = 4 Calories/gram.
5.1 Fats in Our Food
Learning objectives: Describe the roles of fat in our food · Identify obvious and hidden sources of fat ·
Name sources of saturated and unsaturated fats.
Fat is the term we commonly use for lipids. Fats contribute to food’s texture, flavor, and aroma — fat
gives ice cream its smooth texture and rich taste; olive oil flavors salads and Italian and Greek dishes;
sesame oil gives egg rolls and other Chinese foods their aroma.
• But fats add more calories than other nutrients — 9 Calories/gram vs. 4 Calories/gram for
carbohydrate and protein — so a high-fat diet can contribute to weight gain.
• The types of fat matter: too much of the wrong types can increase the risk of heart disease and
cancer.
• The typical American diet contains about 35% of calories from fat — at the high end of the
recommended range ⭐.
• Some fat is naturally present (meats, dairy, nuts, seeds, vegetable oils); much is added by
manufacturers in processing and by consumers (butter, margarine, salad dressings, sauces).
EXCI 204 · Chapter 5 · Page 1
,Figure 5.1b — Fat added in processing, preparation, and at the table ⭐
Food without added fat Fat (g) Food with added fat Fat (g)
Salad (1 cup) 1 Salad (1 cup) with 2 Tbsp salad dressing 14
Baked potato (medium) 0 Baked potato (medium) with sour cream and 11
butter
Tortilla (1 oz) 1 Tortilla chips (1 oz) 6
Macaroni (1 cup) 1 Macaroni and cheese (1 cup) 16
Spinach (1 cup) 0 Creamed spinach (1 cup) 14
Oatmeal (1 cup) 4 Oatmeal cookies (3) 10
Black coffee (12 oz) 0 Caramel macchiato (12 oz) 8
Figure 5.1a: olive oil, salmon, eggs, and almonds are natural sources of fat; the fat in cakes and
croissants is added in preparation; fruits, vegetables, and grains are generally low in fat unless it is
added. A teaspoon of butter on toast adds 5 g of fat.
FORMULA ⭐
Calories added by fat
Calories from fat = grams of fat × 9
Use it to turn any “grams of fat” figure into Calories — e.g., to see how much energy a topping,
dressing, or cooking method adds.
• Added fat = (fat in the prepared food) − (fat in the plain food); multiply the difference by 9.
• Trap: this gives Calories from fat only, not the food’s total Calories.
WORKED EXAMPLE — calculated from textbook numbers
Applying × 9 to Figure 5.1
• Butter on toast: 5 g × 9 = 45 Calories from one teaspoon.
• Salad dressing: 14 g − 1 g = 13 g added → 13 × 9 = 117 Calories from 2 Tbsp of dressing.
• Macaroni → macaroni and cheese: 16 − 1 = 15 g → 135 Calories of added fat.
• Spinach → creamed spinach: 14 − 0 = 14 g → 126 Calories of added fat.
Obvious vs. hidden fat. Some fat is obvious — butter on toast, the fat around a steak, the oil on
pepperoni pizza. Not all is obvious: cheese, ice cream, and whole milk are high in fat, and foods we think
of as carbohydrate sources (baked goods, noodle and rice dishes, snack foods) make up much of the fat
in our diets. Frying adds hidden fat — French fries start as low-fat potatoes but soak up oil.
EXCI 204 · Chapter 5 · Page 2
, EXAM EXAMPLE — FIGURE 5.2
Hidden fats at breakfast
You can see the fat in 2 strips of bacon (8 g), but the 16 g in the muffin and the 10 g in ½ cup of fried
hash brown potatoes are less obvious. 2 eggs provide 14 g.
Calculated from these numbers: total = 16 + 8 + 14 + 10 = 48 g fat → 48 × 9 = 432 Calories from fat.
Only the bacon’s 8 g (≈ 17% of the fat) is “visible.”
Type of fat and dietary pattern. High intakes of saturated fat (meat, dairy) and trans fat (until recently
common in processed foods) are associated with more heart disease and certain cancers. Diets high in
unsaturated fats from fish, nuts, and vegetable oils seem to protect against chronic disease. A healthy
diet includes the right kinds of fats along with plenty of whole grains, fruits, and vegetables.
Concept Check (5.1):
1. Why does a low-fat salad dressing have fewer calories per serving than regular dressing?
2. What are some hidden sources of fat in the diet?
3. Which types of foods are sources of saturated fat?
5.2 Types of Lipids
Learning objectives: Explain the relationship between triglycerides and fatty acids · Compare saturated,
monounsaturated, polyunsaturated, omega-6, omega-3, and trans fatty acids · Describe how
phospholipids and cholesterol are used in the body · Name food sources of each.
Lipids are substances that do not dissolve in water. When we say “fat,” we usually mean triglycerides,
which make up most of the lipids in food and in our bodies. Triglycerides contain fatty acids. Two other
lipid types important in nutrition but present in smaller amounts are phospholipids and sterols.
KEY DEFINITION ⭐
lipid — (Described in text) Substances that do not dissolve in water; “fat” is the term commonly used
for lipids.
KEY DEFINITION ⭐
triglyceride — The major type of lipid in food and the body, consisting of three fatty acids attached
to a glycerol molecule.
KEY DEFINITION ⭐
fatty acid — A molecule made up of a chain of carbons linked to hydrogens, with an acid group at
one end of the chain.
KEY DEFINITION ⭐
phospholipid — A type of lipid whose structure includes a phosphorus atom.
EXCI 204 · Chapter 5 · Page 3
, KEY DEFINITION ⭐
sterol — A type of lipid with a structure composed of multiple chemical rings.
Triglycerides and Fatty Acids ⭐
A triglyceride = the three-carbon molecule glycerol + three fatty acids (any combination). A fatty acid is
a chain of carbons with an acid group (COOH) at one end; the other end is the omega (methyl) end — a
carbon attached to three hydrogens. Each carbon in between is attached to two carbons and up to two
hydrogens (Figure 5.3).
Counting the parts — glycerol-based lipids ⭐
Molecule Glycerol backbone Fatty acids Other
attached
Triglyceride 1 (3 carbons) 3 —
Phospholipid (e.g., 1 2 Phosphate group in place of
lecithin) the 3rd fatty acid
Monoglyceride 1 1 Product of triglyceride
digestion
Fatty acid chain lengths ⭐
Chain length Number of carbons
Short-chain fatty acids 4 to 7
Medium-chain fatty acids 8 to 12
Long-chain fatty acids More than 12
Most fatty acids in plants and animals 14 to 22
The fatty acids in a triglyceride determine its function in the body and properties in food. “Trans fat”
and “saturated fat” really mean trans fatty acids and saturated fatty acids.
KEY DEFINITION
saturated fat / unsaturated fat / trans fat — (Described in text) Everyday terms for triglycerides rich
in saturated, unsaturated, or trans fatty acids — when we say “trans fat” or “saturated fat” we really
mean trans fatty acids and saturated fatty acids.
Saturated vs. unsaturated. Classified by whether they contain carbon-carbon double bonds. A double
bond forms between adjacent carbons when each has only one hydrogen attached. The number and
location of double bonds affect food properties and health effects.
EXCI 204 · Chapter 5 · Page 4
EXCI 204 — Food for Sport · Chapter Study Notes (with formulas & calculations)
Chapter Overview
Lard — an animal fat from swine — was until relatively recently the principal fat Americans used to
prepare food; in the 1800s the fat from salt-cured pork went into everything from soap to candles.
During the Long Depression of the 1870s, William Procter and James Gamble sought cheaper fats for
soap and settled on palm and coconut oil (→ Ivory soap, so high in fat it floated). They then turned to
cottonseed oil, a textile waste product. A German chemist’s 1907 process — hydrogenation — made a
solid fat from a liquid oil, leading to Crisco, which replaced virtually every tub of lard. Almost a century
later it was recognized that the trans fats in hydrogenated oils increase heart disease risk, which led the
FDA to remove them from foods.
The chapter covers: (5.1) fats in our food; (5.2) triglycerides and fatty acids, phospholipids, and sterols;
(5.3) lipid digestion, absorption, and transport by lipoproteins; (5.4) lipid functions — essential fatty
acids, eicosanoids, and fat as energy; (5.5) lipids in heart disease, cancer, and obesity; and (5.6) fat and
cholesterol recommendations, choosing fats, food labels, and fat replacers. This chapter contains
several calculations (% of calories from fat, label % DV, “percent lean”) — each is boxed as a FORMULA
where it appears and collected at the end.
KEY CONCEPT ⭐
Energy values you need for this chapter
• Fat = 9 Calories/gram — more than twice carbohydrate or protein.
• Carbohydrate = 4 Calories/gram; protein = 4 Calories/gram.
5.1 Fats in Our Food
Learning objectives: Describe the roles of fat in our food · Identify obvious and hidden sources of fat ·
Name sources of saturated and unsaturated fats.
Fat is the term we commonly use for lipids. Fats contribute to food’s texture, flavor, and aroma — fat
gives ice cream its smooth texture and rich taste; olive oil flavors salads and Italian and Greek dishes;
sesame oil gives egg rolls and other Chinese foods their aroma.
• But fats add more calories than other nutrients — 9 Calories/gram vs. 4 Calories/gram for
carbohydrate and protein — so a high-fat diet can contribute to weight gain.
• The types of fat matter: too much of the wrong types can increase the risk of heart disease and
cancer.
• The typical American diet contains about 35% of calories from fat — at the high end of the
recommended range ⭐.
• Some fat is naturally present (meats, dairy, nuts, seeds, vegetable oils); much is added by
manufacturers in processing and by consumers (butter, margarine, salad dressings, sauces).
EXCI 204 · Chapter 5 · Page 1
,Figure 5.1b — Fat added in processing, preparation, and at the table ⭐
Food without added fat Fat (g) Food with added fat Fat (g)
Salad (1 cup) 1 Salad (1 cup) with 2 Tbsp salad dressing 14
Baked potato (medium) 0 Baked potato (medium) with sour cream and 11
butter
Tortilla (1 oz) 1 Tortilla chips (1 oz) 6
Macaroni (1 cup) 1 Macaroni and cheese (1 cup) 16
Spinach (1 cup) 0 Creamed spinach (1 cup) 14
Oatmeal (1 cup) 4 Oatmeal cookies (3) 10
Black coffee (12 oz) 0 Caramel macchiato (12 oz) 8
Figure 5.1a: olive oil, salmon, eggs, and almonds are natural sources of fat; the fat in cakes and
croissants is added in preparation; fruits, vegetables, and grains are generally low in fat unless it is
added. A teaspoon of butter on toast adds 5 g of fat.
FORMULA ⭐
Calories added by fat
Calories from fat = grams of fat × 9
Use it to turn any “grams of fat” figure into Calories — e.g., to see how much energy a topping,
dressing, or cooking method adds.
• Added fat = (fat in the prepared food) − (fat in the plain food); multiply the difference by 9.
• Trap: this gives Calories from fat only, not the food’s total Calories.
WORKED EXAMPLE — calculated from textbook numbers
Applying × 9 to Figure 5.1
• Butter on toast: 5 g × 9 = 45 Calories from one teaspoon.
• Salad dressing: 14 g − 1 g = 13 g added → 13 × 9 = 117 Calories from 2 Tbsp of dressing.
• Macaroni → macaroni and cheese: 16 − 1 = 15 g → 135 Calories of added fat.
• Spinach → creamed spinach: 14 − 0 = 14 g → 126 Calories of added fat.
Obvious vs. hidden fat. Some fat is obvious — butter on toast, the fat around a steak, the oil on
pepperoni pizza. Not all is obvious: cheese, ice cream, and whole milk are high in fat, and foods we think
of as carbohydrate sources (baked goods, noodle and rice dishes, snack foods) make up much of the fat
in our diets. Frying adds hidden fat — French fries start as low-fat potatoes but soak up oil.
EXCI 204 · Chapter 5 · Page 2
, EXAM EXAMPLE — FIGURE 5.2
Hidden fats at breakfast
You can see the fat in 2 strips of bacon (8 g), but the 16 g in the muffin and the 10 g in ½ cup of fried
hash brown potatoes are less obvious. 2 eggs provide 14 g.
Calculated from these numbers: total = 16 + 8 + 14 + 10 = 48 g fat → 48 × 9 = 432 Calories from fat.
Only the bacon’s 8 g (≈ 17% of the fat) is “visible.”
Type of fat and dietary pattern. High intakes of saturated fat (meat, dairy) and trans fat (until recently
common in processed foods) are associated with more heart disease and certain cancers. Diets high in
unsaturated fats from fish, nuts, and vegetable oils seem to protect against chronic disease. A healthy
diet includes the right kinds of fats along with plenty of whole grains, fruits, and vegetables.
Concept Check (5.1):
1. Why does a low-fat salad dressing have fewer calories per serving than regular dressing?
2. What are some hidden sources of fat in the diet?
3. Which types of foods are sources of saturated fat?
5.2 Types of Lipids
Learning objectives: Explain the relationship between triglycerides and fatty acids · Compare saturated,
monounsaturated, polyunsaturated, omega-6, omega-3, and trans fatty acids · Describe how
phospholipids and cholesterol are used in the body · Name food sources of each.
Lipids are substances that do not dissolve in water. When we say “fat,” we usually mean triglycerides,
which make up most of the lipids in food and in our bodies. Triglycerides contain fatty acids. Two other
lipid types important in nutrition but present in smaller amounts are phospholipids and sterols.
KEY DEFINITION ⭐
lipid — (Described in text) Substances that do not dissolve in water; “fat” is the term commonly used
for lipids.
KEY DEFINITION ⭐
triglyceride — The major type of lipid in food and the body, consisting of three fatty acids attached
to a glycerol molecule.
KEY DEFINITION ⭐
fatty acid — A molecule made up of a chain of carbons linked to hydrogens, with an acid group at
one end of the chain.
KEY DEFINITION ⭐
phospholipid — A type of lipid whose structure includes a phosphorus atom.
EXCI 204 · Chapter 5 · Page 3
, KEY DEFINITION ⭐
sterol — A type of lipid with a structure composed of multiple chemical rings.
Triglycerides and Fatty Acids ⭐
A triglyceride = the three-carbon molecule glycerol + three fatty acids (any combination). A fatty acid is
a chain of carbons with an acid group (COOH) at one end; the other end is the omega (methyl) end — a
carbon attached to three hydrogens. Each carbon in between is attached to two carbons and up to two
hydrogens (Figure 5.3).
Counting the parts — glycerol-based lipids ⭐
Molecule Glycerol backbone Fatty acids Other
attached
Triglyceride 1 (3 carbons) 3 —
Phospholipid (e.g., 1 2 Phosphate group in place of
lecithin) the 3rd fatty acid
Monoglyceride 1 1 Product of triglyceride
digestion
Fatty acid chain lengths ⭐
Chain length Number of carbons
Short-chain fatty acids 4 to 7
Medium-chain fatty acids 8 to 12
Long-chain fatty acids More than 12
Most fatty acids in plants and animals 14 to 22
The fatty acids in a triglyceride determine its function in the body and properties in food. “Trans fat”
and “saturated fat” really mean trans fatty acids and saturated fatty acids.
KEY DEFINITION
saturated fat / unsaturated fat / trans fat — (Described in text) Everyday terms for triglycerides rich
in saturated, unsaturated, or trans fatty acids — when we say “trans fat” or “saturated fat” we really
mean trans fatty acids and saturated fatty acids.
Saturated vs. unsaturated. Classified by whether they contain carbon-carbon double bonds. A double
bond forms between adjacent carbons when each has only one hydrogen attached. The number and
location of double bonds affect food properties and health effects.
EXCI 204 · Chapter 5 · Page 4
