chapter 15a

Copyright © 2012 Pearson Education, Inc.

Chapter 15aNutrition and

Weight Control

Betty McGuireCornell University

Lecture Presentation


Nutrition and Weight Control

Planning a healthy diet Nutrients Food labels Energy balance Obesity Weight-loss programs Eating disorders


Planning a Healthy Diet

MyPyramid Food guide released by the U.S. Department

of Agriculture (USDA) to help plan a well-balanced diet Personalized

12 different pyramids based on age, gender, level of activity


Planning a Healthy Diet

A healthy lifestyle includes Choosing foods wisely Staying within your calorie needs Engaging in physical activity


Nutrients

Food provides Fuel for cellular activities Building blocks for

Cell division Maintenance Repair

Molecules, such as vitamins, needed to coordinate body processes

Water for cellular reactions and the proper cellular environment


Nutrients

A nutrient is a substance in food that Provides energy Becomes part of a structure Performs a function in growth, maintenance,

or repair


Nutrients

Lipids Fats Oils Cholesterol

95% of the lipids found in food are triglycerides Consist of three fatty acids attached

to a glycerol


Nutrients

Fatty acids differ in their degree of saturation Saturation = extent to which each carbon in

the fatty acid is bonded to as many hydrogen atoms as possible


Nutrients

Saturated fat Contains all the hydrogen atoms it can hold Solid at room temperature Most comes from animal sources


Nutrients

Unsaturated fats Polyunsaturated

Can hold four or more additional hydrogen atoms

Monounsaturated Can hold two or more additional hydrogen

atoms Liquid at room temperature (e.g., oils) Come from plant sources


Nutrients

Functions of fat Ready source of energy Insulation Cushion for vital organs Components of cell membranes Construction of myelin sheaths Absorption of fat-soluble vitamins (A, D, E,

and K) Cholesterol is the structural basis for steroid

hormones


Nutrients

A high-fat diet is associated with Obesity High blood pressure Atherosclerosis Increased risk of type 2 diabetes Certain cancers

Colon, prostate, lung


Nutrients

Low-density lipoproteins (LDLs) Bad form of cholesterol

Deposit cholesterol in the artery walls High-density lipoproteins (HDLs)

Good form of cholesterol Carry cholesterol from cells (and possibly

artery walls) to the liver for elimination


Nutrients

Indicator of risk: Ratio of total cholesterol to HDLs should not

exceed 4:1


Nutrients

Dietary fats Saturated fats

Found in meat, butter, cheese, whole milk Boost harmful LDLs

Trans fats Formed when hydrogen atoms are added

to unsaturated fats (oils) to stabilize or solidify them

Found in packaged foods Boost harmful LDLs and lower good HDLs


Nutrients

Dietary fats (cont.) Monounsaturated fats

Found in oils (olive, canola, peanut) and nuts

Lower total blood cholesterol and LDLs Polyunsaturated fats

Lower total blood cholesterol and LDLs


Nutrients

Carbohydrates Simple carbohydrates

Monosaccharides and disaccharides Include refined sugars Provide energy but have no other nutritive

value “empty calories” Complex carbohydrates

Polysaccharides Include starches and fiber Provide energy and other nutrients


Nutrients

Dietary fiber Found in all plants eaten for food Humans cannot digest Benefits

Good for the heart and blood vessels Lowers LDLs but does not lower the

beneficial HDLs Good for digestive health

Absorbs water, making stools easier to pass


Nutrients

Glycemic response A measure of how quickly a serving of food

is converted to blood sugar (glucose) Glycemic index

A numerical ranking of carbohydrates based on their glycemic response

Ranges from 0 to 100 Foods with a low value cause a modest,

gradual increase in blood sugar and are recommended


Nutrients

Proteins Chains of amino acids that are digested and

delivered to the cells Human proteins contain 20 different kinds of

amino acids 11 amino acids can be made by the body 9 must be supplied by the diet = essential

amino acids


Nutrients

Proteins (cont.) Types

Complete Contain ample amounts of all the

essential amino acids Most animal proteins

Incomplete Low in one or more of the essential

amino acids Most plant proteins


Nutrients

Complementary proteins Combinations of incomplete proteins from

two or more plant sources that together supply ample amounts of all the essential amino acids

Important in vegetarian diets


Nutrients

Vitamins Organic (carbon-containing) compounds that

are needed in minute quantities Usually function as coenzymes


Nutrients

Vitamins (cont.) Categories

Water-soluble C and various B vitamins

Fat-soluble A, D, E, and K

Except for vitamin D, our cells cannot make vitamins, so we must obtain them from food


Nutrients

Minerals Inorganic substances essential to many life

processes Examples include calcium, phosphorus,

potassium, sodium, and chloride


Nutrients

Water Perhaps the most important nutrient Functions

Transports material through our bodies (in blood and lymph)

Provides a medium for chemical reactions Lubricates and cushions organs Helps regulate body temperature (sweat)


Nutrients

PLAY | Diet Meals


Food Labels

Using the information on food labels can help you make healthy choices

Examine Serving size Calories % Daily values


Energy Balance

The body requires energy for Maintenance of basic body functions Physical activity Processing food that is eaten


Energy Balance

Basal metabolic rate (BMR) Energy needed strictly for maintenance Generally represents 60–75% of the body’s

energy needs Declines with age


Energy Balance

Physical activity Dietary Guide for Americans recommends

30 minutes of moderate activity on most days of the week Aerobic exercise reduces risk of heart

disease and lowers blood pressure Weight-bearing exercise reduces risk

of osteoporosis Regular physical activity reduces stress

and risk of many chronic diseases


Obesity

Body Mass Index (BMI) Evaluates your weight in relation to

your height Provides a reliable indicator of body fat BMI > 30 is generally considered unhealthy

and an indication of obesity


Obesity

Health risks associated with obesity Disease of the heart and blood vessels

Raises total cholesterol levels and lowers beneficial HDLs

High blood pressure Type 2 diabetes Gallstones Degenerative joint diseases


Obesity

PLAY | Gastric Bypass Surgery


Weight-Loss Programs

Successful weight-loss programs usually include Reduction in the number of calories

consumed Increase in energy expenditure Behavior modification



The number of calories required daily depends on Activity level Age

Recommended ways to reduce calories Reduce fatty foods Avoid sugars Increase fiber (filling)



PLAY | Fast Food Diets


Eating Disorders

Weight loss can be dangerous Anorexia nervosa

Deliberate self-starvation Body weight 85% or less than expected

for height Bulimia

Binge eating large amounts of food, following by purging

Serious eating disorders can be fatal


Eating Disorders

Negative effects of anorexia nervosa Poor bone health Breakdown of proteins for energy

Reduction in mass of skeletal and heart muscle

Dehydration Electrolyte imbalance


Eating Disorders

Negative effects of bulimia Esophageal injuries Tooth decay Gum disease Dehydration Constipation Electrolyte imbalance

chapter 15a

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