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Chapter 7Chapter 7

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ProteinsProteins Chapter 7Chapter 7

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Chapter Learning OutcomesChapter Learning Outcomes1.1. List the primary functions of proteins in the List the primary functions of proteins in the

body.body.

2.2. Identify the basic structural unit of proteins.Identify the basic structural unit of proteins.

3.3. Distinguish between essential and Distinguish between essential and nonessential amino acids.nonessential amino acids.

4.4. Explain the basic steps of protein synthesis Explain the basic steps of protein synthesis and digestion.and digestion.

5.5. Discuss conditions that contribute to Discuss conditions that contribute to positive nitrogen balance, negative nitrogen positive nitrogen balance, negative nitrogen balance, and protein balance.balance, and protein balance.

Chapter Learning Outcomes Chapter Learning Outcomes (continued)(continued)

6.6. Identify food sources of protein and foods Identify food sources of protein and foods that provide high and low quality proteins.that provide high and low quality proteins.

7.7. Plan meals and snacks that reduce animal Plan meals and snacks that reduce animal protein intake.protein intake.

8.8. Discuss the pros and cons of vegetarian Discuss the pros and cons of vegetarian diets.diets.

9.9. Describe how protein-energy malnutrition Describe how protein-energy malnutrition (PEM) can affect the body.(PEM) can affect the body.

Quiz YourselfQuiz Yourself True or FalseTrue or False

1.1. Animal foods such as meat and eggs are almost 100% Animal foods such as meat and eggs are almost 100% protein. T Fprotein. T F

2.2. Foods made from processed soybeans can be sources Foods made from processed soybeans can be sources of high quality protein. T Fof high quality protein. T F

3.3. An adult body builder should consume about five times An adult body builder should consume about five times more protein than a healthy adult who is not a body more protein than a healthy adult who is not a body builder. T Fbuilder. T F

4.4. Registered dietitians generally recommend that Registered dietitians generally recommend that vegetarians take amino acids supplements to increase vegetarians take amino acids supplements to increase their protein intake. T Ftheir protein intake. T F

5.5. People can nourish their hair by using shampoo that People can nourish their hair by using shampoo that contains protein. T Fcontains protein. T F

How Did You Do?How Did You Do?

1.1. FalseFalse Animal foods such as meat and eggs Animal foods such as meat and eggs contain some protein, lipids, and lots of water.contain some protein, lipids, and lots of water.

2.2. TrueTrue Foods made from processed soybeans Foods made from processed soybeans can be sources of high quality protein.can be sources of high quality protein.

3.3. FalseFalse An adult body builder does An adult body builder does notnot need to need to consume about five times more protein than a consume about five times more protein than a healthy adult who is not a body builder.healthy adult who is not a body builder.

4.4. FalseFalse Registered dietitians do Registered dietitians do notnot generally generally recommend that vegetarians take amino acids recommend that vegetarians take amino acids supplements to increase their protein intake.supplements to increase their protein intake.

5.5. FalseFalse Hair is composed of protein, not living Hair is composed of protein, not living tissue. Therefore, it cannot be nourished.tissue. Therefore, it cannot be nourished.

What Are Proteins?What Are Proteins?

• Complex organic moleculesComplex organic molecules

– Chemically similar to lipids and Chemically similar to lipids and carbohydratescarbohydrates

• Composed of carbon, hydrogen, oxygen, andComposed of carbon, hydrogen, oxygen, and nitrogennitrogen

• The human body contains ~100,000 different The human body contains ~100,000 different proteins.proteins.

Variety of Protein FunctionsVariety of Protein Functions

AllAll cells in the body contain proteins.cells in the body contain proteins.

Specific types of proteins include:Specific types of proteins include:• StructuralStructural proteins in cartilage, ligaments, proteins in cartilage, ligaments,

bones, hair, skin, and nailsbones, hair, skin, and nails• ContractileContractile proteins that enable muscles to proteins that enable muscles to

movemove• PigmentPigment proteins such as proteins such as melaninmelanin

determine color of eyes, hair, and determine color of eyes, hair, and skin skin • ClottingClotting proteins that are needed for blood proteins that are needed for blood

clottingclotting

Functions of Proteins (continued)Functions of Proteins (continued)

• Certain hormones are proteinsCertain hormones are proteins– HormonesHormones are chemical are chemical

messengers that regulate body messengers that regulate body processes and responses.processes and responses.

• Examples include insulin and glucagon.Examples include insulin and glucagon.

• Enzymes are proteinsEnzymes are proteins– Compounds that speed up (Compounds that speed up (catalyzecatalyze) )

chemical reactions without becoming chemical reactions without becoming part of the products.part of the products.

Functions of Proteins (continued)Functions of Proteins (continued)

• TransportTransport proteins proteins– Oxygen and many nutrients are Oxygen and many nutrients are

transported by special proteins.transported by special proteins.

• Proteins aid in Proteins aid in fluid balance.fluid balance.

Fluid Balance Fluid Balance and Proteinsand Proteins

Proteins in blood, Proteins in blood, such as such as albuminalbumin, , help maintain the help maintain the

proper distribution of proper distribution of fluids within fluids within

bloodstream and bloodstream and body tissues.body tissues.

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What is Edema?What is Edema?

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Acid-base Balance and ProteinsAcid-base Balance and Proteins

• Acid-base balanceAcid-base balance– Maintaining the proper pH of body Maintaining the proper pH of body

fluidsfluids

• Blood and tissue fluid must Blood and tissue fluid must maintain a maintain a pHpH of of 7.35 to 7.457.35 to 7.45

• Acidic Acidic - having an - having an excess of Hexcess of H++

• Too basic Too basic –– not enough H not enough H++

• Proteins act as Proteins act as buffersbuffers by by accepting or releasing Haccepting or releasing H+.+.

Amino AcidsAmino Acids

• Proteins are made of smaller units called Proteins are made of smaller units called amino amino acids.acids.

• 20 different amino acids in human proteins20 different amino acids in human proteins• Each amino acid is composed of:Each amino acid is composed of:

– An amino or a nitrogen-containing groupAn amino or a nitrogen-containing group • Amino groupAmino group has nitrogen bonded to 2 hydrogen atoms has nitrogen bonded to 2 hydrogen atoms

– R-groupR-group (side chain) (side chain) — varies with each amino acid— varies with each amino acid• Acid groupAcid group – acid portion – acid portion

Amino Acid: Basic Chemical StructureAmino Acid: Basic Chemical Structure

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Classifying Amino Acids

Essential Amino AcidsEssential Amino Acids• Cannot be made by the body, so Cannot be made by the body, so

must be supplied in the dietmust be supplied in the diet• 9 of the 20 amino acids9 of the 20 amino acids

Nonessential Amino AcidsNonessential Amino Acids• Can be made by the bodyCan be made by the body• 11 of the 20 amino acids11 of the 20 amino acids

The Essential and Nonessential Amino AcidsThe Essential and Nonessential Amino Acids

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Proteins in FoodsProteins in Foods

• Nearly Nearly allall foods contain some protein, but foods contain some protein, but no natural food is 100% protein.no natural food is 100% protein.

• Animal foods typically have more protein Animal foods typically have more protein than plant foods.than plant foods.– Seeds, tree nuts, and legumes supply more Seeds, tree nuts, and legumes supply more

protein than fruit or the edible leaves, roots, protein than fruit or the edible leaves, roots, flowers, and stems of vegetables.flowers, and stems of vegetables.

Protein Contents of Some Commonly Eaten Protein Contents of Some Commonly Eaten FoodsFoods

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What Are Legumes?What Are Legumes?

• LegumesLegumes– Plants that Plants that

produce pods with produce pods with a single row of a single row of seedsseeds

Examples:Examples: Soybeans, peas, Soybeans, peas,

peanuts, lentils, peanuts, lentils, and beansand beans

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Protein QualityProtein Quality

• High-quality proteinHigh-quality protein– Protein that contains all 9 essential amino acids in Protein that contains all 9 essential amino acids in

amounts that support growthamounts that support growth– “ “Complete protein”Complete protein”– Most animal products and products made with Most animal products and products made with

processed soyprocessed soy

• Low-quality proteinLow-quality protein– Protein that lacks or has inadequate amounts of one Protein that lacks or has inadequate amounts of one

or more of the essential amino acidsor more of the essential amino acids– Most plant foods (except processed soy) Most plant foods (except processed soy) and gelatinand gelatin

What Happens to Protein in Your Body?What Happens to Protein in Your Body?

• How Your Body Synthesizes ProteinsHow Your Body Synthesizes Proteins– Cells assemble the 20 amino acids in Cells assemble the 20 amino acids in

specific sequences according to information specific sequences according to information provided by provided by DNA.DNA.

– Amino acids are connected by Amino acids are connected by peptide peptide bonds.bonds.

– PeptidesPeptides• Chains of fewer than 15 amino acidsChains of fewer than 15 amino acids

– PolypeptidesPolypeptides• Proteins made of > 50 amino acidsProteins made of > 50 amino acids

What Is a Protein?What Is a Protein?

• Each distinctive bead Each distinctive bead in the illustration in the illustration representsrepresentsa different aminoa different amino

acid. acid.

• The “hook” that The “hook” that connects the “beads” connects the “beads” represents a represents a peptide peptide bond.bond.

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Peptide BondPeptide Bond

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Protein SynthesisProtein Synthesis

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A ProteinA Protein Takes Shape Takes Shape

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Sickle Cell AnemiaSickle Cell Anemia• If the DNA code is faulty, the wrong amino acid may be inserted If the DNA code is faulty, the wrong amino acid may be inserted

into a protein. For example, into a protein. For example, sickle cell diseasesickle cell disease that affects red that affects red blood cells blood cells

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Protein DenaturationProtein Denaturation

DenaturationDenaturation• Altering a protein’s natural shape and function by Altering a protein’s natural shape and function by

exposing it to conditions such as heat, alcohol, acid, exposing it to conditions such as heat, alcohol, acid, and physical agitationand physical agitation– Heat denatures the protein in raw eggs.Heat denatures the protein in raw eggs.– Acidic lemon juice “curdles” the protein in milk.Acidic lemon juice “curdles” the protein in milk.– Hydrochloric acid denatures food proteins in the Hydrochloric acid denatures food proteins in the

stomach, making them easy to digest.stomach, making them easy to digest.– Physical agitation includes whipping protein-rich Physical agitation includes whipping protein-rich

foods (e.g., beaten egg whites).foods (e.g., beaten egg whites).

DenaturationDenaturation

Insert Figure 7.9Insert Figure 7.9

Protein TurnoverProtein Turnover

• Protein turnoverProtein turnover– Breaking down old or unneeded proteins into Breaking down old or unneeded proteins into

amino acids and recycling the amino acidsamino acids and recycling the amino acids

• Amino acid “pool”Amino acid “pool”– Amino acids that have not been incorporated Amino acids that have not been incorporated

into proteinsinto proteins

• Endogenous amino acidsEndogenous amino acids– Those available from the amino acid poolThose available from the amino acid pool

• Exogenous proteinsExogenous proteins – Those from dietary sourcesThose from dietary sources

Transamination and DeaminationTransamination and Deamination

TransaminationTransamination– Transfer of nitrogen-containing group from an Transfer of nitrogen-containing group from an

unneeded amino acid to a unneeded amino acid to a carbon skeletoncarbon skeleton, , forming an amino acidforming an amino acid

DeaminationDeamination– Removal of nitrogen-containing group from an Removal of nitrogen-containing group from an

unneeded amino acidunneeded amino acid

Example of Transamination and Example of Transamination and DeaminationDeamination

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The Liver and The Liver and Deamination Deamination

AmmoniaAmmonia ( (NHNH33) )

is converted to is converted to ureaurea that the that the

kidneys excrete kidneys excrete in urine.in urine.

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Nitrogen BalanceNitrogen Balance

Nitrogen balanceNitrogen balance (or equilibrium) (or equilibrium)Balancing nitrogen intake with nitrogen lossesBalancing nitrogen intake with nitrogen losses

Positive nitrogen balancePositive nitrogen balanceBody retains more nitrogen than it losesBody retains more nitrogen than it loses

Negative nitrogen balanceNegative nitrogen balanceBody loses more nitrogen than it retainsBody loses more nitrogen than it retains

PPositive Nitrogen Balanceositive Nitrogen BalanceOccurs during growth, pregnancy, recovery from illness, and Occurs during growth, pregnancy, recovery from illness, and

as a result of certain hormones and resistance exerciseas a result of certain hormones and resistance exercise

insert Figure 7.12insert Figure 7.12

Nitrogen EquilibriumNitrogen EquilibriumOccurs when healthy adults meet protein and energy needsOccurs when healthy adults meet protein and energy needs

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NegativeNegative Nitrogen Balance Nitrogen BalanceOccurs with Occurs with protein intake, kidney disease, blood loss, bed protein intake, kidney disease, blood loss, bed

rest, fever, injuries, burns, or rest, fever, injuries, burns, or thyroid hormone or cortisol thyroid hormone or cortisol

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How Much Protein Do You Need?How Much Protein Do You Need?

• Daily protein needs of healthy adults:Daily protein needs of healthy adults:– RDARDA = = 0.80.8 g/kg body wt g/kg body wt

• Protein needs increase during periods of Protein needs increase during periods of growth, pregnancy, lactation, and growth, pregnancy, lactation, and recovery from illness or injury.recovery from illness or injury.

Determining Protein NeedsDetermining Protein Needs

• Using the RDA formula of 0.8 g of protein/kg of Using the RDA formula of 0.8 g of protein/kg of body wt, what is the RDA for protein for a person body wt, what is the RDA for protein for a person weighing 165 lbs?weighing 165 lbs?

1)1) Convert weight in lbs to weight in kg Convert weight in lbs to weight in kg

(165 (165 2.2 = 75 kg)2.2 = 75 kg)

2)2) Multiply kg of body wt by 0.8Multiply kg of body wt by 0.8

75 X 0.8 = 6075 X 0.8 = 60

Therefore, a person weighing 165 lbs will meet his/her Therefore, a person weighing 165 lbs will meet his/her RDA for protein by consuming 60 g of protein per dayRDA for protein by consuming 60 g of protein per day

Protein Digestion Protein Digestion

• Protein digestion begins in the Protein digestion begins in the stomach.stomach.– Hydrochloric acidHydrochloric acid denatures proteins denatures proteins– PepsinPepsin, an enzyme, digests proteins into smaller , an enzyme, digests proteins into smaller

polypeptides.polypeptides.

• Polypeptides enter the Polypeptides enter the small intestinesmall intestine – The enzymes The enzymes trypsintrypsin and and chymotrypsinchymotrypsin break down break down

polypeptides into shorter peptides and individual polypeptides into shorter peptides and individual amino acids.amino acids.

Protein AbsorptionProtein Absorption

• AbsorptionAbsorption occurs in the occurs in the small intestinesmall intestine– Absorptive cells release enzymes that digest Absorptive cells release enzymes that digest

most small peptides into individual amino most small peptides into individual amino acids.acids.

– Individual amino acids and some di- and Individual amino acids and some di- and tripeptides enter absorptive cells, where they tripeptides enter absorptive cells, where they are completely digested to amino acids.are completely digested to amino acids.

After Absorption…After Absorption…

• Amino acids enter Amino acids enter portal veinportal vein and travel to and travel to the the liverliver– Liver keeps some amino acids for its own use Liver keeps some amino acids for its own use

and releases others into general circulation.and releases others into general circulation.

• MostMost proteins are digested and amino proteins are digested and amino acids absorbedacids absorbed– Very littleVery little protein is eliminated in protein is eliminated in feces.feces.

What Is A Food Allergy?What Is A Food Allergy?

• AllergyAllergy– Inflammatory response resulting when body’s Inflammatory response resulting when body’s

immune system reacts inappropriately to a immune system reacts inappropriately to a substance that is typically harmlesssubstance that is typically harmless• Allergen Allergen — the offending substance — the offending substance

– Most food allergens are proteins that escape Most food allergens are proteins that escape digestion and are absorbed as digestion and are absorbed as whole proteins.whole proteins.

Common Signs of Food AllergiesCommon Signs of Food Allergies

Signs occur within a few minutes or Signs occur within a few minutes or couple of hours and typically couple of hours and typically include:include:– Hives (red raised bumps on skin) Hives (red raised bumps on skin) – Swollen or itchy lipsSwollen or itchy lips– Skin flushingSkin flushing– Scaly skin rash (Scaly skin rash (eczemaeczema))– Difficulty swallowingDifficulty swallowing– Wheezing and difficult breathingWheezing and difficult breathing– Abdominal pain, vomiting, and diarrheaAbdominal pain, vomiting, and diarrhea

Common Food AllergensCommon Food Allergens

Protein-rich foods- Cow’s milk- Eggs- Peanuts

- Wheat

- Soybeans

- Fish and shellfish

Nonproteins- Food dyes

- Sulfites added to:• Wine

• Fruits

• Vegetables

• Shellfish

Who Develops Food Allergies?Who Develops Food Allergies?

• People with People with family historyfamily history of food or of food or environmental allergiesenvironmental allergies

• ~ ~ 4%4% of children 5 to 17 yrs of children 5 to 17 yrs

• Most Most outgrowoutgrow by age 5 yrs by age 5 yrs– Allergies to nuts, seafood, and Allergies to nuts, seafood, and

wheat are typically not outgrownwheat are typically not outgrown

• ~ ~ 2%2% of adults of adults

Gluten and Celiac DiseaseGluten and Celiac Disease

• GliadinGliadin– Protein found in Protein found in glutengluten of wheat, buckwheat, of wheat, buckwheat,

barley, and rye barley, and rye – Triggers inflammatory response in small Triggers inflammatory response in small

intestineintestine– Condition called Condition called celiac diseaseceliac disease

• Symptoms includeSymptoms include– Chronic diarrhea, weight loss, poor growth in Chronic diarrhea, weight loss, poor growth in

childrenchildren

• TreatmentTreatment– Avoid glutenAvoid gluten-containing foods-containing foods

Treatment of Food AllergiesTreatment of Food Allergies

• AvoidAvoid offending foods offending foods• ReadRead food labels to check for food labels to check for

allergensallergens• Food Allergen Labeling and Consumer Food Allergen Labeling and Consumer

Protection Act requires manufacturers to Protection Act requires manufacturers to identify allergenic ingredients on product identify allergenic ingredients on product labels.labels.

• EducateEducate teachers and other adults teachers and other adults of allergic children’s need to avoid of allergic children’s need to avoid certain foodscertain foods

Treating Severe Allergic ReactionsTreating Severe Allergic Reactions

Emergency

treatment for

anaphylaxis (a

severe allergic

reaction) may

involve injecting a special medication.

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girl using epi

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What Is PKU?What Is PKU?

PhenylketonuriaPhenylketonuria (PKU) (PKU)

– GeneticGenetic disorder disorder– Affects ~ 1/15,000 infants Affects ~ 1/15,000 infants – Caused by Caused by lack of enzymelack of enzyme

that converts the amino that converts the amino acid acid phenylalaninephenylalanine to to another compoundanother compound

– If undiagnosed, infant will If undiagnosed, infant will develop develop mental retardationmental retardation

by first birthday.by first birthday.

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Low Phenylalanine DietLow Phenylalanine Diet

InfancyInfancy

Phenylalanine-freePhenylalanine-free formula and low-formula and low-phenylalanine foodsphenylalanine foods

Childhood and adult yearsChildhood and adult years

Allowed:Allowed: fruits, vegetables, and special low-fruits, vegetables, and special low-phenylalanine foodsphenylalanine foods

Avoided:Avoided: nuts, milk and milk products, eggs, nuts, milk and milk products, eggs, meats, and foods and beverages containing meats, and foods and beverages containing aspartameaspartame (e.g., Nutrasweet or Equal) (e.g., Nutrasweet or Equal)

Protein Consumption PatternsProtein Consumption Patterns

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MyPyramid Plan: MyPyramid Plan: Recommendations for Protein IntakeRecommendations for Protein Intake

• Choose Choose lean or low-fat meat and poultrylean or low-fat meat and poultry– Lean cuts of beef include:Lean cuts of beef include:

• Round steaks, top round, loin, top sirloin, chuck and arm Round steaks, top round, loin, top sirloin, chuck and arm roastsroasts

– Lean pork cuts include:Lean pork cuts include:• Loin, tenderloin, and center loinLoin, tenderloin, and center loin

• ChooseChoose “extra lean” ground beef “extra lean” ground beef– At least 90% leanAt least 90% lean

• TrimTrim visible fat from meats visible fat from meats

UnderstandingUnderstanding Nutritional Labeling Nutritional Labeling

• Nutrition FactsNutrition Facts panel only panel only provides grams of proteinprovides grams of protein

• Panel does Panel does notnot provide provide information concerning information concerning protein protein qualityquality

– Judge protein quality by Judge protein quality by reviewing items in the reviewing items in the ingredient listingredient list

Figure 7.15

Eating Well for LessEating Well for Less

- Substitute eggs, milk, cheese, and yogurt for - Substitute eggs, milk, cheese, and yogurt for meat, fish, or poultry.meat, fish, or poultry.

- Make meals that contain less animal proteins - Make meals that contain less animal proteins and more plant proteins.and more plant proteins.

- Extend cereal proteins with eggs and milk (e.g., - Extend cereal proteins with eggs and milk (e.g., pancakes, waffles, crepes, or cereal with milk).pancakes, waffles, crepes, or cereal with milk).

- Include more legumes in meals (e.g., chili, bean - Include more legumes in meals (e.g., chili, bean soups, and stews) while reducing meat content.soups, and stews) while reducing meat content.

Combining Complementary ProteinsCombining Complementary Proteins

Complementary combinationsComplementary combinations

- - Mixing certain plant foods to provide all essential Mixing certain plant foods to provide all essential amino acids without adding animal proteinsamino acids without adding animal proteins

Amino acids often low or limiting in plant Amino acids often low or limiting in plant proteins:proteins:

tryptophan, threonine, lysine,tryptophan, threonine, lysine, and and methioninemethionine

Complementary Dishes

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Peanut Butter (legume) on Bread (grain)

Couscous (grain) with Chickpeas (legume)

Complementary Protein DishesComplementary Protein Dishes

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VegetarianismVegetarianism

VegetariansVegetarians- - People who eat plant-based dietsPeople who eat plant-based diets

Types of VegetariansTypes of Vegetarians• Lactovegetarian Lactovegetarian

• Consumes milk and milk productsConsumes milk and milk products • OvovegetarianOvovegetarian

• Consumes eggsConsumes eggs

• LactoovovegetarianLactoovovegetarian• Consumes eggs and milk and milk productsConsumes eggs and milk and milk products

• VeganVegan

• Consumes Consumes onlyonly plant foods plant foods

Is Vegetarianism a Healthy Lifestyle?

Pros• Compared to

nonvegetarians, vegetarians tend to:– Weigh less – Have less heart disease

(eat less saturated fat and cholesterol)

– Often exercise more, meditate for relaxation, and avoid tobacco and alcohol

Cons• If diets are poorly

planned, vegetarians may lack:– Kilocalories– High-quality protein– Omega-3 fatty acids– Vitamins B-12 and D– Zinc, iron, and calcium

Vegetarian Children and Teens

Children• May be difficult to consume adequate protein and

energy, because plant foods tend to be filling– Growth rates of vegan children need close

monitoring.

Teens

Pro: Can be healthy diet because more fruits and vegetables are consumed

Con: May be at risk of anorexia nervosa, an eating disorder

Vegetarian Women

Pregnancy• May need vitamin B-12 supplements

– Infant could be deficient in B-12

Breastfeeding• Breastmilk may be deficient in vitamin B-12

– Infant may develop severe developmental delays if fed breast milk that lacks vitamin B-12

Meatless Menu Planning IdeasMeatless Menu Planning Ideas

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Protein AdequacyProtein Adequacy

Excessive Protein IntakeExcessive Protein Intake– May May risk of heart disease and cancers of the risk of heart disease and cancers of the

colon/rectum, prostate, pancreas, and breastcolon/rectum, prostate, pancreas, and breast

What about High-Protein Weight-Loss Diets?What about High-Protein Weight-Loss Diets?– Diets decrease feelings of hunger and increase Diets decrease feelings of hunger and increase

sense of fullness.sense of fullness.– More info about safety of high-protein weight loss More info about safety of high-protein weight loss

diets in diets in Chapter 10Chapter 10

Protein DeficiencyProtein Deficiency

Uncommon in the U.S.Uncommon in the U.S.

– May occur in:May occur in:• elderly or low-income people elderly or low-income people • persons with alcoholism, anorexia nervosa, or persons with alcoholism, anorexia nervosa, or

intestinal tract disordersintestinal tract disorders

Kwashiorkor and MarasmusKwashiorkor and Marasmus

Protein-energy malnutrition (PEM)Protein-energy malnutrition (PEM)– Results from chronic lack of food or poor food choicesResults from chronic lack of food or poor food choices

Two types of PEM:Two types of PEM:– KwahsiorkorKwahsiorkor

• Adequate energy intake but intake of high-quality Adequate energy intake but intake of high-quality protein is lowprotein is low

» EdemaEdema

– MarasmusMarasmus• Starvation—extreme weight lossStarvation—extreme weight loss

Marasmic Marasmic KwashiorkorKwashiorkor

Characterized by Characterized by edema in the edema in the

abdomen, lower abdomen, lower legs, and feetlegs, and feet

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Severe Severe Protein-Protein-Energy Energy

MalnutritionMalnutritionInsert figure 7.18Insert figure 7.18

Chapter 7 HighlightBuilding a Bulkier Body

How to increase muscle mass?How to increase muscle mass?

• Resistance training is the only safe and Resistance training is the only safe and reliable way.reliable way.

• Dietitians generally do not recommend Dietitians generally do not recommend eating large amounts of protein-rich eating large amounts of protein-rich foods.foods.

How Resistance Training Builds Bigger Muscles

• During training, muscle proteins break down.

– Synthesis occurs during recovery and lasts ~ 24 to 48 hrs.

• Muscles grow larger if adequate energy and protein are available (positive nitrogen positive nitrogen balancebalance).

Proteins: General Advice for Athletes

• Since carbohydrates spare proteins, eat a snack before or after exercise that includes adequate carbohydrate and protein.

• Protein supplements are notnot needed for healthy persons.– If supplements are used, avoid those that contain a

single amino acid.

• Avoid high-protein diets, especially ones high in red meats.